Transcript: Astronomy with the Unaided Eye

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Fraser: Astronomy Cast Episode 193 for Monday June 7, 2010, Astronomy with the Unaided Eye. Welcome to Astronomy Cast, our weekly facts-based journey through the cosmos, where we help you understand not only what we know, but how we know what we know. My name is Fraser Cain, I’m the publisher of Universe Today, and with me is Dr. Pamela Gay, a professor at Southern Illinois University Edwardsville. Hi Pamela, how’re you doing?

Pamela: I’m doing well… it’s so good to be recording in the same month that we’re existing in!

Fraser: I know… I know… Yeah, the summer of episodes is grinding on and we’re pretty much caught up, and we hope to get ahead because you’re going to be travelling like crazy in July.

Pamela: Yes, if you’re going to be at TAM, I shall see you at TAM. If you’re a scientist and going to be at the NASA lunar forums, I will be at the NASA lunar forums. If you’re an educator and you’re going to be at the Astronomical Society of the Pacific meeting, I will be at the Astronomical Society of the Pacific meeting. And then both Fraser and I will be at DragonCon…

Fraser: In September…

Pamela: In September… and then both Fraser and I will be at the US Science and Engineering Festival in Washington DC in October.

Fraser: There you go. Ok, so we talk a lot about telescopes here at Astronomy Cast, but you don’t really need any special equipment to appreciate what the night sky has to offer. Just head outside with some sky charts, maybe a planisphere, some friends, and hot chocolate, and you’re good to go. Let’s talk about what kinds of things you can see with just your eyes. And before we did this episode… the real title should be “Astronomy with the ***** Eye,” not “Astronomy with the Unaided Eye.” But…

Pamela: But there’s spam filters…

Fraser: The spam filters! I know! So, this is the thing, right, we say that… we put that as our title, then kids won’t be able to access this site because their nanny filters will go off, in fact, whoever’s doing the transcript for this…

Pamela: Don’t use the word *****.

Fraser: Leave this whole part out… it’s not even in there… so, as a web-master, this is one of the sort of little pieces of experience that we’ve built up is to never use that word when we’re talking about astronomy with the unaided eye. So, unaided… meaning no binoculars, no telescope, just your eyeballs enjoying astronomy.

Pamela: And if any of you have problems with nanny filters and my last name… this just occurred to me… some of you may be having that issue. Let us know and we’ll figure how to work around it…

Fraser: That’s true, yeah. Ok, so… I love doing this. A lot of my favorite part of astronomy is just being able to go out, take some friends outside, show them the constellations, especially when really interesting things are happening. So what kinds of things, like general class of things, can you see just without any telescope, binoculars, anything?

Pamela: The most amazing thing… and this requires going out in the dark somewhere… like really dark… like drive so that you can’t see a city on any skylines. Drive to the middle of nowhere, take a tent, take a sleeping bag, take friends, take food and water, and look up in the summer and just absorb the Milky Way.

Fraser: Yeah.

Pamela: It’s the most amazing thing. And if you’re in the southern hemisphere, the dust lanes through the Milky Way… at one angle it looks like an emu… at another angle it looks like a floppy-eared dog. And you can actually lay there with your friends and spend the entire night going, “And the dust lanes look like…” and just making stuff up like you’re looking at clouds.

Fraser: And so what are these dust lanes that we’re seeing?

Pamela: Well, it’s a combination of… first of all there’s this bright stripe through the sky that’s the equivalent of where the disk of the Milky Way is. So we live embedded in a pancake of material. And if you can imagine holding a giant 10-foot diameter pancake up with a hole off-center and sticking your head in the hole… where you look around and see pancake, that’s the disk of the Milky Way in the sky. Now, just like you can’t look all the way through the pancake because there’s pancake material, you can’t look all the way across the disk of the Milky Way because there’s dust. And so when we look out, where we see really bright, it’s literally thousands and thousands and thousands of stars packed side by side, lighting up this bright stripe. But there’s also lots of dark molecular clouds, lots of cold gas, lots of stuff out there that’s just blocking the starlight. And the dark bands through the Milky Way is where it’s particularly dusty.

Fraser: So, to see the Milky Way, you definitely have to get out of the city, you have to get, I would say, 30-40 kilometers away from a city to really start see it. We can see it where I live. I live in a city, but it’s not a very bright… not a very large city. And still, the Milky Way doesn’t look that nice. And if I go a few kilometers out of the city, then things get a lot darker and a lot better.

Pamela: Yeah, where I live in southern Illinois, I can’t see it from my house, but I have a horse… an old, mangy-ish… not really, he’s very cute… I have an old horse… and the barn where I keep him… if I hang out too late, I can see the Milky Way out there. So, if you have a friend with cows or horses, likely if you’re out at their barn and you shut the lights off, you can see the Milky Way.

Fraser: But I think in general, everything that we’re going to recommend, the further you get away from the city the better. Whether you’re seeing comets, meteor showers, the planets, anything… get away from the city. And also, the later you stay up, the better it gets. So, you know, if you’re gonna start to see some stars… 10 o’clock at night… it’s a completely different story when it’s three in the morning.

Pamela: Yes. And well the other thing with three in the morning is that people shut off all their house lights, so as people go to bed, the sky gets darker and darker as all of the lights get turned off, and you can actually see that in how many stars you can see.

Fraser: Yeah, one thing that I’ll do when I take the kids camping is we’ll just go to bed at a normal time, but I’ll set an alarm and then, yeah… at two in the morning I wake up everybody… I wake up the whole family. And they’re like, “I don’t want to!” And then I show them the stars and they’re like… “Oh, yeah, this is good!” And then if we’re watching a meteor showers, etc., then that’s what we’ll do. Then you can really appreciate it. Then it just blows your mind.

Pamela: And this is the year for the meteor showers, and we’re starting to come up on it. I know you’re looking forward to August.

Fraser: Yeah, August 2010… so if you’re listening to this after that, I’m sorry… you missed out. But August 2010, the Perseid meteor showers are going to be just 2 days away from a new moon, so you’re going to have the darkest possible skies, plus you’re going to have a triple conjunction… you’re going to have three planets very close to the moon… I think it’s Jupiter [Saturn], Venus, and Mars are all going to be very close to a crescent moon. And then you’re going to have the Perseid meteor shower. So, right now… put on your calendar…

Pamela: August 12-13…

Fraser: August 12-13… the 13th is a Friday, so, you know…

Pamela: You can go out and celebrate your superstition with a doubly superstitious night.

Fraser: Well, no, but also you don’t have to work on Saturday so you can stay up really late.

Pamela: Yeah, and they’re estimating 60 meteors per hour with this one, which is fairly consistent… and the Perseids often put on a nice bright show.

Fraser: Yeah, really bright one. So, make sure you do that. Find some friends, schedule a time, go camping the 13th of August, 2010… or 12th… it’ll be fine. Ok, so we’ve talked about the Milky Way… what else can we see with just our eyes?

Pamela: Well, it varies with the year. Not with the year… with the time of year. Since we’re in summer, we might as well start with summer. One of my other favorite objects to search out… there’s two of them actually… the easier one to find is the Andromeda Galaxy. You can actually see it as this fuzzy… wow, is there really something there? Wait, if I turn my eyes sideways… wow, there’s something there. If I look directly at it, it kind of disappears. You have to learn how to use your off-center vision to see it best. But, Andromeda actually shows up as something fuzzy the size of a fingernail up on the sky, and that’s about as cool as it gets.

Fraser: Isn’t that about the most distant thing you can see with the unaided eye?

Pamela: In the northern hemisphere, it’s the only galaxy that can be seen by normal people on a regular basis, ***** eye, and it just really stands out. It’s off the legs of the constellation Pegasus, and it’s fairly easy to see. It’s going to be a really late-night object this time of the year. Then it gets higher and higher in the sky as we get towards fall. But right now, early in the morning, it’s up as a morning object… those of you who see the sun rise, just get up a little bit earlier and it’s there waiting for you. The other object, though, that is perfectly high in the sky right now is M13. This is a globular cluster, so it’s something that’s out of the disk of the galaxy. It’s literally a cluster of thousands and thousands of really old stars packed into a tight ball that if you did look through a telescope, would kind of look like a dead bug splattered on the eyepiece. It’s in the constellation of the Warrior, and there’s just this fuzzy splatter print on the Warrior’s chest.

Fraser: That’s Hercules, right?

Pamela: It’s Hercules… it’s in the constellation Hercules.

Fraser: And you can see the Summer Triangle, which is actually made up of three different constellations, but in the summer, it’s your go-to constellation first.

Pamela: And it helps you find the Milky Way, because the Milky Way goes right down the center of the Summer Triangle. So the three corner stars are Altair, which is in Aquila, the eagle; Vega, which is in Lyra, which is a type of harp; and then Deneb, which is in Cygnus, the swan. Aquila and Cygnus are both flying along the Milky Way.

Fraser: Right. And so, in the summer anyway, they will be pretty much the three first stars that you see. And then you can watch them over the course of the night as the rest of the constellation fills in. So summer… and then of course in summer, later on in the evening, Perseus comes in quite nicely.

Pamela: Right.

Fraser: Which looks like, from my vantage point anyway, an upside-down V.

Pamela: And between Perseus and Cassiopeia there’s the Double Cluster, which is another thing that if you’re in a dark, dark, dark, dark site you can sort of go… oh, there’s something there.

Fraser: Yeah. Then you look at it and it disappears. Something faint…

Pamela: But Cassiopeia is always striking to look at because it’s either this big number 3 or this big W or this big letter M, depending on what time of day it is. And there’s people who actually learn how to tell time as a function of where in the year we are by looking at Cassiopeia. It’s really neat to take these very linear constellations that are up all night, and watch through the night as they rotate through the sky. You can also do this with the Milky Way in both the northern and the southern hemisphere. As you watch the Milky Way through the night, it will slowly rotate through the sky, which is just fun.

Fraser: And it’s the summer right now when we’re recording this, but there are other things that look quite great over the course of the year… although it gets colder, anyway for us… to go outside…

Pamela: So just to bring one more thing up as we stay in the summer is that if you live near the equator, you are a lucky soul. The object I’m about to mention can be seen by most of both hemispheres, and that’s Sagittarius, the teapot. Although in the southern hemisphere it wouldn’t hold any water.

Fraser: Upside-down teapot…

Pamela: Yes.

Fraser: But it sure looks like a teapot… absolutely… no question.

Pamela: Yes, and imagine just taking your little kids out, and you can do the “I’m a Little Teapot” song and show them where on the sky the spout is and the handle is. It’s just a neat way to engage little tiny kids in astronomy. And Sagittarius, when you’re looking at it, you’re looking at the center of our galaxy. You can actually start to figure that out because as you look at the Milky Way, you can see how it’s much wider when you’re looking at Sagittarius, and then it narrows further away.

Fraser: Right. And then at other times of the year?

Pamela: So, moving into the fall, Orion starts to join us in the sky. We have Andromeda high in the sky overhead, and we’re just losing Sagittarius come September… it’s a very early evening object and sets very quickly.

Fraser: Orion is coming… Orion is great! I mean, once you learn Orion you’ll see Orion’s belt, you’ll make out the shape of the shoulders, even his shield and sword. And then inside the sword is the Orion Nebula, another one of those blurry spots on the sky.

Pamela: And what’s really cool about the fall sky is you can go out and you look at the Orion Nebula, the fuzzy sword, and those are stars that are still in the process of pulling themselves together. There’s going to be supernovae in the future of all these young bright, bright blue stars burning themselves out and exploding, but they’re not there yet. The stars are still in the process of forming with the smallest ones. So as you look at Orion, that’s a star-forming region. It’s going to become an open cluster… cc open cluster in the making, I guess. But then if you just look a little to the west, closer towards the ecliptic, towards the constellation Taurus, the bull. In that general direction, if you keep going past Taurus, the bull, you get to the Pleiades. This is an older open cluster, where all the stars have formed, where almost all the gas has been consumed or blown out. You’re now looking at the Subaru car symbol, and you’re seeing what Orion will become in the future. The stars are a little bit more spaced out… and it even gets better. If you now go back to Taurus, and you pause at Aldebaran, the big burnt-orange star… University of Texas… symbol is the bull… Taurus is a bull… burnt-orange University of Texas star… can you tell where I got my PhD? This is where the Hyades cluster is. As you’re looking at Taurus, there’s this over-density of stars that’s kind of spread out, and that’s what the Pleiades will become in its future. So here we’re looking at three different versions of the same object, at three completely different ages. All within a few fists of one another on the sky, this whole set of stellar evolution traced out.

Fraser: And a little later into the winter, we start to get Sirius coming up in the night sky, and that’s the brightest star in the night sky.

Pamela: Right. And it’s also a star… and you can never make this out with any normal human telescope or your eyes, let alone… Sirius also has a white dwarf companion. So when you’re looking at Sirius, you’re actually looking at two stars… a normal star and a little white dwarf beside it.

Fraser: And then what about into spring?

Pamela: So, as we get into spring, well now we have Gemini, the twins Castor and Pollux, straight overhead. And Cancer is out, and Cancer… if you’re in a dark site and you look at it, there’s this triangle of stars that you can just make out. In the center of this triangle of stars is this fuzzy cotton ball. And that fuzzy cotton ball is another cluster—it’s M44. And it’s just really dramatic in dark-enough skies. When I was down at Sutherland Observatory in South Africa a few months ago, I had to ask somebody, “What’s that big bright fuzzy thing over there?” just because it was just so shocking and I hadn’t been in skies that dark when Cancer was up. So that’s something very dramatic. It’s interesting to watch as the year progresses, just seeing how everything changes, because come March, we still have the Pleiades in the sky… we still have Orion… but they’re now in completely different places. It’s that march of the constellations that a lot of people just don’t notice. When you take the time to notice it, every year it’s like you get to watch your friends come back in the sky.

Fraser: And those lucky ducks that live in the southern hemisphere have a whole bunch of stuff that we just have no way of seeing in the north.

Pamela: Right. And it’s really shocking if you go to a dark site in the southern hemisphere because the Large and Small Magellanic Clouds look like someone took a fist full of Milky Way… tore it off and threw it to the side. Literally it’s like a fist on the sky worth of extra stars.

Fraser: Wow. And you can see Alpha Centauri, which is the system that contains the closest star to Earth, which we can’t see from the north.

Pamela: And the Tarantula Nebula… now I know this is supposed to be all unaided observing, but the one object that if you’re in the southern hemisphere, if you visit the southern hemisphere, if you think about visiting the southern hemisphere, you should go for this reason. If you look through just a 12-inch telescope at the Tarantula Nebula, you’re actually looking at the face of a tarantula. It really surprised me… it’s just like… big face, staring at you through the eyepiece.

Fraser: So we’ve talked about some things that we can kind of see all year long, quite dependably. So if you go out in August, you’re going to be able to see the Summer Triangle every year. What kinds of resources would you suggest people take to find their way around the sky?

Pamela: The best thing you can possibly do is either print out the monthly sky maps that you can get at skymaps.com. They’re good, they’re solid, they update them every month… they’re free! They tell you where the planets are. One of the things that periodically throws me off is Leo the Lion periodically grows a nose that’s just a planet that wandered across the ecliptic. It’s good to have sky maps to show you what these strange, mysterious additional stars and constellations are.

Fraser: Yeah, so free… go to skymaps.com, you can print off some free sky charts, and you’re set. Or if you want to spend a little money, get a planisphere or even… I like Nightwatch… as a book…

Pamela: Yes, Nightwatch is good. And there’s a yearly… if you love big, beautiful, stunning art, there’s a yearly sky calendar that comes out that you can get through Sky and Telescope that is super-sized. It’s about 18 inches tall, and just has the most amazing artwork. It updates you on every year’s… how good are the meteor showers going to be… The meteor showers can vary a couple of days each year. I was born during the Geminids meteor shower, but it’s not every year on my birthday.

Fraser: Right, and this was the second part that I wanted to talk about which is that some things happen on very specific days. These are the meteor showers. You can go out any day in August and see the Summer Triangle… you don’t have to be that precise about it. But if you want to see the Perseid meteor shower, then you do have to really go out within a couple of days. So there are meteor showers that you can see… what are some other objects that we can see?

Pamela: Well, one of the neat things to challenge yourself to do each month is to be the first person to see the crescent moon. There is nothing quite as magnificent low on the horizon as a couple-day old moon that is visible only just as the sun is setting. So, that’s a fun challenge. Then there are the times when a moon and planets are side by side on the sky. These are just random events that have beauty and you can go out and it’s neat to think that I’m looking, right now… at the same time… at Mars, Venus, and the moon. And that’s kinda cool. A few years ago Jupiter passed in front of the Beehive Cluster and so you get these merging of different events. Then there’s also solar and lunar eclipses as well. We’re going to have a partial lunar eclipse coming up on June 26, a solar eclipse coming up on July 11, and another lunar eclipse coming up on December 21. And with these good star charts, they can help you keep attention to when are all of these different things going to happen.

Fraser: And you can also see some stuff that are man-made as well… there’s satellites. If you spend any time looking up at reasonably dark skies, you’re going to see satellites go overhead. One of the games that we play is “Who’s the first person to spot a satellite?” Then, if you’re organized, you can go to the NASA website, and you can find out times when the International Space Station is going to be flying overhead… or the space shuttle… or Hubble.

Pamela: And another good resource to go to that also lets you in on the iridium satellites and random spy satellites and even comets is heavens-above.com. You can put in your location, specify latitude and longitude… Google Maps will help you figure that out… and it will tell you all of the cool stuff with ten days worth of predictions of what is going to be over your place on the planet. And there’s for some cities Twitter feeds set up by Rob Simpson of Orbiting Frog, so if you’re in New York City, for instance, you can go to Over New York. If you’re in Paris, there’s Over Paris. There’s a whole variety of different cities he’s set up, and I think he’ll often set up new cities if there’s a bunch of people who are interested. These will Twitter at you when a satellite is overhead that you’re able to see.

Fraser: Yeah, once again I would really recommend going to the NASA site, find out when the space station’s going to be flying overhead. Then schedule a party… schedule a time that you and your friends are going to be outside… you’re having a barbeque… then it gets late, and you have the timer go off and you go “Ok everybody… the space station’s going to go overhead!” You gather everyone around and you look up and right on cue, this super bright star shows up over the horizon and crosses the sky in about a couple of minutes and it’s gone. Everyone will think you’re a genius!

Pamela: And there’s also just neat things that we can’t always predict how cool they’re going to be like comet McNaught. Last year comet McNaught just came out of nowhere. No one knew how fabulous this comet was going to be. It’s back again this year… it’s just barely visible… it’s magnitude 5.6… it’s hanging out next to Perseus right now. But there’s often comets that crop up at least once or twice a year that are easily seen with unaided eyes, and it’s just really cool to go out and see these pieces of ice that might have originated in another solar system.

Fraser: Yeah, and once a decade you’ll get a comet like Hale-Bopp or Hyakutake. And with those, you’ve really got to get organized and get out of town, and see that with dark skies. A friend of mine and I went on a road trip to get out of Vancouver to see Hale-Bopp and it was just astonishing to see that comet on the horizon…. just amazing.

Pamela: And comet Hale-Bopp is one that when it was up, you looked at it and it was a large chunk of your windshield. And then when Hyakutake was out, I was observing at McDonald Observatory and I remember that it just happened to always be in my windshield when I was driving toward the observatory, so I felt like I was following the comet to the observatory. It was literally half my windshield wide looking at it and just hung low over the horizon, truly magnificent objects, but they only come around every few years. So keep an eye out for when they’re around and then just go absorb the experience.

Fraser: And I would also recommend getting to know when some planets are in the sky. We’ll usually announce some really interesting stuff on Universe Today, but there’s other sites as well. You can say… ok, and get to know… then you see the really bright Venus on the horizon or even high up in the sky even a few hours after the sun’s gone down. Then you just tell people. I will point a person towards Venus and say “Hey, did you know that’s Venus?” And they’re like… whoa, I didn’t realize that I could see Venus… and then “Yeah, and there’s Jupiter over there.” If it’s off to the west in the evening, it’s probably Venus. If it’s high up in the sky and it’s bright, it’s probably Jupiter. They’re the first things to show up. If it looks quite red, it’s probably Mars.

Pamela: And because Fraser and I both know the email is coming again… you will, at some point in the coming months as Mars rounds its way back around the sun, get the email—and Fraser knows what I’m about to talk about—saying that Mars appears bigger than the moon. That will never happen. So when your friends send this to you… you, too, can laugh at them, and then take them out and actually look at Mars, because Mars is cool to look at. It is so amazingly red and most people just don’t realize that you can actually see colors in the stars… and there’s reds and there’s blues and you do see the color… except for green—there isn’t green.

Fraser: And there’s a little bit of astronomy that you can do during the day… which is that you can observe the sun but…

Pamela: And the moon…

Fraser: And the moon. That’s true, but you can observe the sun, just don’t use your eyeballs directly. But, you can use a pinhole projector to project the disk of the sun onto the white piece of paper, and you can actually see sunspots. But don’t look with your eyes… don’t look with your eyes!

Pamela: Resist the temptation…

Fraser: Yeah. Well, that was great, Pamela, I think we… is there anything else that we can see?

Pamela: I think we hit the highlights. Go out and fall in love with the stars.

Fraser: So, right now, schedule the Perseids on August 12-13… get some friends together… do a sleepover… stay out late… leave the city… go camping…

Pamela: Remember bug spray… remember bug spray…

Fraser: Sure… and see the Perseids because you’ll remember it your whole life.

Pamela: And we’d love to hear your experiences on the BAUT forums where we have the Astronomy Cast pages.

Fraser: That would be great. Or, just send us an email, and that would be great. Alright, well thanks a lot, Pamela. And I’ll see you outside!

Pamela: Yes! Sounds good, Fraser. I’ll talk to you later.

Shownotes

Mars Science Lab rover, a.k.a Curiosity

Mars Sample Return mission — How Stuff Works

Methane on Mars — Universe Today

GRAIL (Gravity Recover and Interior Laboratory

LADEE (Lunar Atmosphere and Dust Environment Explorer)

Europa Jupiter System Mission, joint mission by NASA and ESA

JUNO mission

CoRoT Telescope

CoRoT — Weird Collection of Worlds in the Latest Cache of CoRoT Exoplanets --Universe Today

Terrestrial Planet Finder (Fraser’s favorite!)

Detecting neutrinos — The Why Files

Detecting Dark Matter — Discover Magazine

WMAP

JSWT

Gravitational Waves — NASA Goddard

LISA mission

Brane theory

Oscillating Universe Theory — Universe Today

This transcript is not an exact match to the audio file. It has been edited for clarity.

Shownotes

• Auroras – Michigan Tech
• Auroras – Exploratorium
• Aurora FAQ’s – University of Alaska-Fairbanks Geophysical Institute
• Earth’s magnetic field – GSU
• Earth as a bar magnet — Windows to the Universe
• How Mass Spectrometry works — HowStuffWorks
• Atomic oxygen — Single oxygen atoms as compared to oxygen molecules (two oxygen atoms) found in air. Atomic oxygen is found in the upper atmosphere where it has been created by solar radiation. It is extremely reactive and corrodes must materials radidly.
• Molecular hydrogen is found in the interstellar medium where it is generated by ionization of molecular hydrogen from cosmic rays. It has also been observed in the upper atmosphere of the planet Jupiter.
• Molecular oxygen is a molecule that is composed of two oxygen atoms that has no color, odor, or taste. It is present in both the atmosphere and the oceans, and solar radiation with wavelengths less than 242 nm can break it back into oxygen atoms. One of these oxygen radicals in turn can combine with O2 to form ozone.
• Different colors are produced by different atoms and molecules — University of Alaska
• Aurora seen from space — Environmental Graffiti
• Aurora on Jupiter — APOD
• Jupiter’s Aurora Helped by Io — Universe Today
• Aurora on Saturn — HubbleSite
• Infrared Aurora on Saturn – Universe Today
• Coronal Mass Ejections — SWRI
• Sunspots – Exploratorium
• SpaceWeather.com
• Auroras in the 1800′s affecting telegraph communication
• The current deep solar minimum — Science@NASA
• Upcoming Solar Maximum — Universe Today
• STEREO mission
• 3-D movies of Sun from STEREO

Transcript: Auroras

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Fraser: Astronomy Cast Episode 163 for Monday November 9, 2009, Auroras. Welcome to Astronomy Cast, our weekly facts-based journey through the cosmos, where we help you understand not only what we know, but how we know what we know. My name is Fraser Cain, I’m the publisher of Universe Today, and with me is Dr. Pamela Gay, a professor at Southern Illinois University Edwardsville. Hey, Pamela.

Pamela: Hey, Fraser, how’s it going?

Fraser: Good. A little under the weather with H1N1.

Pamela: Even the internets can’t escape the swine flu.

Fraser: Yeah, I don’t know, it’s been running around my hometown, and my whole family got it. It passed through us pretty quickly. We had a fever for a couple of days… cough that I know is going to stick around for a couple of weeks, but didn’t feel too run down. As flus go, it was no problem at all.

Pamela: Well, I really appreciate you putting yourself together to be recording this week, before the holidays.

Fraser: Oh, it’s no problem, seriously. I’ll go out and run 5K after this… it’s fine. It’s funny because you remember how sick I was last year, but this year… even though I’ve got swine flu, it’s no problem at all. So, when the sun’s solar winds crash into the earth’s magnetosphere, we get to enjoy an incredible light show called the aurora… or the northern and southern lights. Let’s learn about what causes these incredible phenomenon, and the best places and times that you can see them with your own eyes. Alright, now Pamela, have you ever seen an aurora with your own eyes?

Pamela: I have… and they’re really creepy. When I was a small child, I saw the northern lights and they looked like Scooby Doo ghosts, except no human being inside. It completely freaked me out. But when I got older, I learned to sit in the backyard with a beer and appreciate them.

Fraser: But, you’re not that far north, right, so not a very easy time to see them.

Pamela: Well, each of the times I’ve seen them I’ve been up in the northeast… either in Massachusetts as a kid or up in New Hampshire with some friends one summer.

Fraser: Yeah, so here, I’m just about at the 49th parallel, and we get them… depending on how the solar activity is going. But, I’ve seen one time when it was great. It was the middle of summer, so it wasn’t quite that dark, but just a beautiful splash of red in the sky… sort of moving back and forth… looks like a creature… like you said, like a ghost. It doesn’t feel like anything else that’s astronomy-related. It’s so organic…

Pamela: Well, and it moves and changes color, and depending on where you are, it may just appear as this white sheen in the sky.

Fraser: Yeah, and so you’re not quite sure if that’s what you’re seeing… then it moves a bit, and you’re not sure if your eyes are playing tricks on you… So there are times when you really see it and there’s no question that that’s what it is, and then other times when it’s kind of hard to make it out. So hopefully with this episode, we’ll be able to bring in all the latest science and give you a much better shot at being able to see the auroras for yourself. So what’s the underlying phenomenon? What’s going on here?

Pamela: Well, at the end of the day, the problem is that the earth has a magnetic field line, and when high-energy particles, or in fact any particles, from the solar wind interact with this magnetic field, the charged particles will tend to follow the magnetic field lines back down toward the surface of the earth. As they collide with things in the atmosphere, you end up with a light show. I guess the best starting point is to imagine one of those little iron filing magnet things that many of us played with as kids or that we saw in our textbooks. If you take a bar magnet, and the earth is basically a bar magnet, and you move it through iron filings, you get these arcs that go from the north magnetic pole to the south magnetic pole, forming ever-increasing loops. That’s what our Earth has, and those loops, they connect up to the surface of the earth at the north and south pole, and then extend out great distances beyond even our atmosphere.

Fraser: Right, and I think we’ve seen the pictures online and in books and stuff of where it really looks like someone has put a bar magnet right in the middle of the earth, and then it has the lines—the magnetic field lines—going from the north pole back over to the south pole in concentric rings… semi-circles. But the way the pictures go, they’re sort of flattened on one side and more like a tail on the other side.

Pamela: Now, one of the things that I get to teach in physics is that any time you have a moving charged particle moving through a magnetic field, it’s going to get accelerated by that magnetic field. In fact, its direction can get changed. This is how, in some cases, mass spectrometers work is you take charged atoms and fire them through a known magnetic field, and if they have a set velocity and you know the magnetic field that they’re moving into, they’ll get arced towards a detector. You can figure out how much they weigh by how much they’re arced.

Fraser: That’s how television works, isn’t? The old tube television…

Pamela: Right, in fact lots and lots of everyday experience—from CSI to how you watch CSI—is all made possible by what happens when you move charged particles through a magnetic field. Now with the planet earth, we’re one giant magnetic field. And in fact the sun also generates one gianter magnetic field. Charged particles moving from the sun out away from the sun will travel out along magnetic fields.

Fraser: And, sorry… so what are these particles, then?

Pamela: Well, they’re electrons, they’re protons, in a few cases they’re charged ions… heavier nuclei that have had electrons stripped off of them for various processes. They’re just particles… the same sort of stuff you find making up everything around you. Just strip off a few electrons and send them flying loose through space.

Fraser: But the trick is… strip off a few electrons, right?

Pamela: Right. So they’re not neutral, and often they’re accelerated to rather ludicrous velocities by the sun. So you have these high-speed charged particles moving from the sun towards the earth. And when the magnetic fields are just right, they’ll travel along the sun’s magnetic fields, and then get tangled up in the earth’s magnetic fields, and plunge down along the magnetic field line through the atmosphere.

Fraser: Now will they go through one or the other? Like, will they go… if they’re oriented one way they’ll go to the north pole, and if they’re oriented the other way they’ll go to the south pole?

Pamela: Well, the way it works is it’s all one large coupled system. It depends in large part where they came off of the surface of the sun. So you’ll end up, a couple times a year… around the equinoxes, actually, and we’re still trying to figure out why this happens… but around the equinoxes, the magnetic fields of the earth and the sun are lined up just right that they end up tangling together. Depending on where the particles came off of the sun, they’ll travel either toward the north or toward the southern poles. Now what’s neat is when you get a really large solar event it just blasts radiation in our direction, and we’ll end up with aurora on both poles of the earth.

Fraser: Right, ok… so I think I’ve got the story so far… you’ve got a stream of particles constantly coming off the sun, right? That’s the solar wind. It’s making its way through space, and it’s got a charge because it’s had some electrons stripped off of these particles, and it also had a certain magnetic field alignment thanks to wherever it was on the sun when it came off. It sort of retains that magnetic alignment and then it makes its way to the earth. Then it interacts with the earth’s magnetic field and dives into one of the poles. Then as it comes through… I guess the part that I don’t really understand is where does the light show part come from?

Pamela: Well, the light show actually comes from stuff that’s in our atmosphere. As these high-energy particles are blasting through our atmosphere, they have a chance to hit an atom here or there. Our atmosphere is filled with things that give off light when you hit them just right. We have atomic oxygen which gives off red light. We have molecular nitrogen which is blue and molecular oxygen which is green. What happens is you’ll end up with one of these high-energy particles whipping itself into say an atomic oxygen molecule. And when this happens, one of the electrons in the atomic oxygen molecule can jump to a higher energy level. So now we have excited atomic oxygen in the upper levels of the atmosphere. That excited atomic oxygen can only stay excited so long. Then it drops to a lower energy level. When it drops to a lower energy level, it gives off a very precise photon of color, a very precise, in this case, red photon of color. And that is what we see as the red aurora that seems to always be the northern-most part of the aurora. That is where the aurora has first started in the highest parts of the atmosphere.

Fraser: Ok, sorry, so the solar wind particles are actually slamming into the various parts of the atmosphere, boosting up their energy level, and then they drop back down and give off photons at that very specific frequency… and that’s what we see.

Pamela: And what we see depends on where in the atmosphere the atoms and molecules are getting excited. So, the atomic oxygen… it’s getting excited at the highest possible levels of the atmosphere. The green color… this is often the most predominant color in an aurora… the green emission is coming from molecular oxygen. These are molecules all throughout our atmosphere and when they get hit, they decay rather quickly. So, after about three-fourths of a second, an excited molecular oxygen molecule is going to give off green light and you end up with these huge… what look like curtains of green light… moving through the sky where the high-energy particles are passing through. These are also occurring at all sorts of different density levels. Now the reason that you get this at so many different places is that this is a fast transition… you whack a molecule, and it goes… oh, I’m excited…. and then it really fast says… no, I’m not… three-fourths of a second later. I can’t even say it as fast as it does it. Then it gives off that energy. With the atomic oxygen that’s giving off the red light, it stays excited for about 2 minutes. Now the problem with that is… in those 2 minutes, something else could whack the atomic oxygen. The denser the atmosphere you’re looking at, the higher the probability of some sort of a collision happening. If that collision happens, it’s going to change the energy of the oxygen and you’re going to end up not necessarily having that pretty, red photon. Instead, you might end up with some sort of kinetic energy going into the system. You can have all sorts of different things happening.

Fraser: Could you boost it higher and higher without it actually being able to drop back down?

Pamela: In theory, yes, but we don’t have the densities or the energies in the atmosphere. So it’s just the probability of one lone atom getting whacked over and over and over. It’s just too low of a probability.

Fraser: Right. So just a fraction of the atoms are actually being struck, so the chances of the same one being hit is pretty rare.

Pamela: Now at the same time we also end up with these blue highlights and that’s all coming from nitrogen emission in our atmosphere. We can end up with all these amazing combinations of color. And exactly how you see it depends, in part, on what’s going on and where you are. So what’s amazing is the photos that the people up on the International Space Station are able to take. Here on the planet Earth we see what we perceive is three-dimensional structure, but we’re never quite sure. It looks like curtains in the sky, but hey… we’re just looking up at the sky, which is really a flat surface. But if you’re able to look down on the aurora, there’re literally these bands of vertical illumination coming up through the atmosphere marking where these waves of solar wind have flown all the way from the sun to the earth’s magnetic field and have just followed these planes of magnetic field lines and now they’re hitting Earth’s atmosphere causing brilliant illumination.

Fraser: Yeah… wow. Yeah, I’ve seen… there’s some amazing pictures that you could see taken by astronauts. And then this same process is being seen on other planets, as well.

Pamela: Anywhere you have an atmosphere and a magnetic field, you can end up seeing aurora. Perhaps the most amazing images that have so far been seen are those of Jupiter. Jupiter has these amazing brilliant aurorae around its northern and southern poles. We have really good images of this from the Galileo spacecraft.

Fraser: And Saturn has them, too.

Pamela: And Io… even the little Galilean moon of Jupiter, because it has this amazing combination of active magnetic fields and atmosphere, it just lights up with aurorae.

Fraser: So I guess there’s just sort of a background chance… there’s always a bit of an aurora must be going on because the solar wind is constantly streaming off of the sun and constantly reaching the earth. But it’s not that strong, right? I mean you’ve got to be pretty close up to the north or south pole to be able to see much, right?

Pamela: And the truth is if you live far enough north, almost any time that it’s dark and it’s moonless and it’s clear… because these things are faint, so you need to get rid of the moon, you need to get rid of any clouds, and you need to have the sun fully out of the sky… no twilight going on. But, if you get rid of all of those these three things, pretty much any night of the year you can see some amount of aurora. But these giant gorgeous aurora displays that we see pictures of in post cards and astronomy books, those are almost always tied to coronal mass ejections. These are times when you end up with a loop of magnetic field poking up from the surface of the sun. It lets loose with all of its energy and all of the particles that were contained within this tangled loop of magnetic field. And if the alignments are just right, it shoots those particles at the planet Earth at high velocities, and they get tangled up in the earth’s magnetic field and can end up causing aurorae all the way down to the middle latitudes of the planet Earth.

Fraser: Right, and so most people… if they’ve seen an aurora… chances are you’re seeing one that is the result of one of these coronal mass ejections.

Pamela: So this is where sunspots start to become so interesting because a lot of times these coronal mass ejections are tied in with some of the really big, beautiful sunspot complexes… so when you start developing these giant sunspots, then you start to increase the probability that… hey, maybe we’re going to get a big flare…. maybe we’re going to get a big coronal mass ejection… which, again, increases the probability of… hey, maybe we’re going to have awesome aurorae. And there’s all sorts of different of websites that are dedicated to looking at space weather, like spaceweather.com, where you can go and you can find out what is tonight’s aurora prediction.

Fraser: Yeah… what is the space weather? I love that you can look up the space weather and get a sense of how the weather’s going to be. You know, for us it’s no real big impact on our daily lives, but you can imagine for future astronauts who are going to make that trip from the earth to the moon being very careful about the space weather. Making sure that there isn’t a big sunspot pointing right at the earth before they make that trip.

Pamela: And that’s where all of this starts to become so important… the same thing that causes beautiful auroral displays on the surface of the planet can wreak havoc on the astronauts’ lives. The highest levels of our atmosphere just start to touch where the International Space Station is orbiting, about 300 miles up. And so when we’re watching these aurorae, sometimes a very high aurora can be seen as high as 350 miles. This means that the space shuttle can actually, if the orbits are just right, fly through a sheet of the northern lights or the southern lights. And that’s kind of amazing to think about, but the magnetic fields that are tied into this… the high-energy particles that are tied into this… there’s a lot of energy stored up in this. In fact there’s a historical case of at one point in the 1800s, there were telegraph operators who during the middle of a particularly violent aurora period where there’s amazing solar winds hitting the earth’s magnetic field, this violently changing magnetic field induced so much current in the telegraph lines that they found that their batteries were causing interference. So they unhooked their batteries for hours and just worked the telegraphs like normal using nothing but the energy generated by the oscillating magnetic field.

Fraser: Wow! That’s a lot of power. Thanks, Sun! So then let’s sort of think of this over time… We’ve got a fairly active sun happening… right now we were on the solar minimum and now we’re moving ourselves towards the solar maximum, which is supposed to be in 2012! So in 2012 we should hit solar max with way more sunspots on the sun, and we’ll be able to see those sunspots crossing… or, I guess the sun is rotating… we’ll be able to see those sunspots as they make their way across the surface of the sun… they’re not moving, the sun is rotating… but anyway, we’re going to get into situations, right, where one of these big sunspot complexes is perfectly aligned directly towards the earth. Then you get an x-ray flash, you get this great big coronal mass ejection coming out, and a release of particles towards the earth. So, then let’s say that that happens… how long does it take for the particles to get from the sun to the earth?

Pamela: It can be anywhere from a few tens of minutes to a few hours to a couple of days. It all depends on how much power is charged up. Now the problem is the really high speed ones, the ones that arrive in tens of minutes vs. in a couple of days, they’re the ones that are most dangerous. This is where space weather forecasting starts to become very important, and also where missions like STEREO become very important. What’s awesome about STEREO is when it’s on the same side of the sun… when the two missions are on the same side of the sun as the planet Earth… they can give us a three-dimensional view of these coronal mass ejections as the mass ejections pass between the two little spaceships. And with a spaceship on either side, we’re able to measure the position of the coronal mass ejection relative to the stars from both sides and go… oh, I know exactly where that coronal mass ejection is going… Earth is fine. Or, oh no, we need to get the earth locked down into safety mode. Let’s get all the satellites tidied up, let’s get all the astronauts back down to the planet Earth… if we have time. So we do look for ways to mitigate the possible badness. One of the strange things that we actually have to think about is how much electricity is being carried on our power lines. The same event that caused the telegraph officers to be able to work their machines without batteries plugged in… today would be devastating to the power grid. When we built the North American power grid… all those power lines that make my house and yours light up across North America… we didn’t realize how much electricity it would some day need to carry. The more current you run through the wires, the more they stretch. If you stretch them too much, they break. So they were designed to be carried with about 80% full load, where full load is the point at which they break. Now a good coronal mass ejection will oscillate the earth’s magnetic field violently. That will create current in those power lines… this is all sorts of complicated physics… we can do an entire show, eventually, dedicated to just this particular effect. But, that changing magnetic field creates current and if you create too much current artificially from coronal mass ejections you start breaking power lines all over North America. This is actually something Phil talks about in his book Death From the Skies. It’s not as big a concern for the astronauts… we can predict… we can lock them into safe places… they’ll be sad, but they should—if we have warning—be ok. But trying to dump enough power off the power grid rapidly so that all the wires are safe, all the power lines are safe… that’s a bit trickier because now you’re starting to deal with all sorts of different nations across the globe all going… ok, less power, less power, less power… and that’s harder to do.

Fraser: But with the modern satellite age… especially with STEREO now… scientists are getting pretty good at predicting when a good light show is probably going to happen… and even how far south people… or north, if you’re trying to see the southern lights… how far away from the pole you can be to actually still see a pretty good light show. And I remember… this happened during the last solar maximum… there were some pretty big events and there were some really good predictions. I was writing a bunch of stories on Universe Today and we were saying… ok, tonight, give it a shot… go outside… look up… and you should see some really great auroras. Then report back to me, and I had lots of people email me… I was in Scotland… I was in England… I was as far south as Texas. People were seeing them all over the world, and it was really great because finally I could say… oh, go outside, go look, and tell me if you see it. We had it here… my dad was telling me about it on Hornby… So there is… so this time around… when 2012 comes around, we should… the world’s not going to end… but we should get really beautiful light shows again, which I think is way better.

Pamela: Yeah, and with little SDO getting launched, NASA’s going to be able to warn us. NASA warning us keeps all the telecommunications satellites safe and allows us time to get our cameras on our tripods. That’s the best way to enjoy these, unfortunately. The human eye isn’t as sensitive to the color green as you might want it to be…

Fraser: Right.

Pamela: But cameras are…

Fraser: And that was my last question… let’s say that you’re bound and determined to see the auroras this time around. You know… we want to see an eclipse… want to see the auroras… So what should you do and where should you go and what should you bring with you, and so on…

Pamela: There’s actually some tour companies that have northern light tours. Some of the best places to go are Alaska and Scandinavia. Pick one… it really doesn’t matter… both of them will make you cold and happy, hopefully. The two ways of looking at them… one is you go up in airplanes and you look through your windows… I don’t think that one is quite the way I want to do it, but I know there’s lots of people that go out and observe the northern lights that way. The other way is to go get yourself someplace far enough north and with a friendly enough bellman that when the northern lights come out, they phone up to your room and tell you to get out of bed and come look. I actually got to see that in Anchorage, Alaska, a few years ago with a meeting of the American Association of Physics Teachers. We all signed up with the hotel bellman, and when the lights started up that night, he called all of our rooms and we all bustled out to the parking lot where the lights were turned off. We all stood and looked out over the mountains at these amazing displays.

Fraser: The problem, of course, is that the best places to see the northern lights are…

Pamela: …the most miserable…

Fraser: …the coldest, right…. and if you’re there in the summer, then the sun never goes down and so you don’t get a chance to see them. So the time you want to see them is when it’s not summer, which sometimes can mean winter, and at night when it’s even colder! And the sky has to be clear, where it’s even colder! So cold weather and northern lights often go hand in hand. My experience was summer on the west coast. I was in shorts and t-shirt, laying on the grass at 1:00 in the morning, watching the light show…

Pamela: You can get lucky any time of year.

Fraser: Yeah, it’s amazing what you can see… if you just show up. Go look for meteors, and if you’re lucky, you might see the northern lights, as well.

Pamela: And one neat way to plan it might be to go see the Leonids somewhere really far north… the big November meteor shower. Because these do tend to show up more around the equinoxes… November is fairly close to an equinox. Another good time to go looking when a lot of the tours are is February and March.

Fraser: And also, stay tuned to the space weather site, because they do a great job of warning when really big coronal mass ejections have been fired at the earth. So you can kind of know the time frame when you should go out and try to watch them. And when they’re really spectacular, you can see them all the way… anywhere in Europe… anywhere almost in the United States… almost anywhere in Asia. So when it’s really going, in a couple of years from now, you should be able to see them if you want to.

Pamela: And the best way to record what you’re seeing is to get yourself a digital SLR camera… something like the Canon EOS Rebel, or similar cameras… something that allows you to have a longer exposure, something that does automatic dark current correction, which is just removing any random electrons you have bouncing around as a standard background level in your camera. Good cameras can make corrections for the background bouncing-around electrons. Go out, record it with a camera, sit back and enjoy. Then when you look at your pictures later go… wow, the camera saw so much more than I did. That’s the sad part, but you can see really cool stuff, too. Warn your little kids what’s going on, otherwise they’re going to be freaking out. But, it’s an amazing experience neither you nor your family will ever forget.

Fraser: Yeah, it’s one of those astronomy holidays that you’ve got to put on the list. In fact, I’m going to go put it on my list right now.

Pamela: Sounds good!

Fraser: Alright, well, thanks a lot, Pamela! We’ll talk to you later.

Pamela: OK. Bye-bye.

Show Notes

• International Dark Sky Association
• Dark Skies Awareness for IYA
• Sky & Telescopes Dark Skies resources
• Dark Sky Society
• GLOBE at Night
• The Great World Wide Star Count
• Dark Sky sites in the US and Canada
• Clear Dark Sky: The same people who bring you the “Clear Sky Clock” also have data on local light pollution, also available as high-resolution maps of light pollution levels. A map for each continent is available for download as separate files.
• A Dark Adapted Eye -- Astroblog
• How to easily dark adapt your laptop screen and flashlights –aperture fever
• DarkAdapted software
• Good Neighbor Outdoor lighting — Sky & Telescope
• Examples of good outdoor lighting — Skykeepers
• Sky quality meter



Transcript: Dark Skies

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Fraser: Astronomy Cast Episode 153 for Monday August 31, 2009: Dark Skies. Welcome to Astronomy Cast, our weekly facts-based journey through the cosmos, where we help you understand not only what we know, but how we know what we know. My name is Fraser Cain, I’m the publisher of Universe Today, and with me is Dr. Pamela Gay, a professor at Southern Illinois University Edwardsville. Hey Pamela.

Pamela: Hey Fraser, how’s it going?

Fraser: Good. So, this is… once again we’re still catching up from the past, but this is Episode 153, and then next Episode 154 is going to be the live show that you did at DragonCon with…

Pamela: Yay!! Seth Shostak.

Fraser: With a few friends, yep. Which, if we put it up on the date, it would be Sept. 7, so it should all work out perfectly. And later on, no one will ever be able to tell our terrible lies… Alright, so if you live in a city, it’s possible that you’ve never seen the Milky Way with your own eyes. So, to really appreciate everything that night skies have to offer, you’ve got to get out of the city, away from the lights, where the skies are really dark. But those places are getting harder and harder to find. So, let’s talk about what you can do to find some dark skies, to fight to make the skies darker, and how to make the most of wherever you live. But first, Pamela, I think we should make everyone drool, can we hear a really cool dark sky story?

Pamela: Oh, for me it was the first time I went observing out at McDonald Observatory. I drove and drove and drove and drove and drove and drove during daylight to get out there because I had homework due, and I couldn’t leave for the observatory until
I finished my homework. I get out there and I’m exhausted, and I’m supposed to spend the entire night awake with a wonderful observer Dr. Phil McQueen learning how to use the 30-inch at McDonald Observatory. And he’s like… look, just make it until 5 in the morning, just make it until 5 in the morning. I didn’t know what was special about 5 in the morning, and I’m pretty much melted into the desk beside the control panel computer when he nudges me and tells me to go outside. I walk out the door… now the thing about McDonald Observatory is the 30-inch telescope isn’t on the top of the mountain, it’s actually on a ring road that’s a little ways down the side of the mountain, so when you step outside you have mountains straight to your left, and then looming over you are the giant domes of the 82-inch telescope and the 107-inch telescope. Then off to your right is just the desert plains of west Texas. I step outside and off to my right in the distance are all along the horizon–Texas thunderstorms… amazing amounts of lightning, and it’s reflecting off the domes that are up the mountain from me. And straight in front of me is comet Hyakutake, which is just fun to say… but it’s huge! It’s taking up a serious amount of the sky in front of me, filling my field of view as though it’s completely hanging on top of the dormitories at the top of the mountain, filling that entire section of the sky… just coming up, or just setting as the case actually was. Then straight overhead from me was the Milky Way like someone had poured it there, and I’d never seen the Milky Way that clearly. I’d seen really dark skies before, but not when the Milky Way was up. It was the type of thing that if you set it up in a planetarium show… lightning going off to the right, straight in front of you–giant comet filling large part of the sky, and straight overhead–Milky Way… no one would believe this planetarium show. But, that’s what I actually saw. I was wide awake all of a sudden, and I made it to sunrise. It was just the most amazing… oh, wow, the sky does this? That summer comet Hyakutake was my best friend because every time I drove out to the observatory it was literally filling my windshield the entire trip if I turned my headlights down.

Fraser: Wow. So, for me, well I grew up on a small island off the west coast of Vancouver Island and pretty far away from civilization, so, in fact, we had really dark skies all the time. But actually just a couple of years ago I took my… my kids and I go back every summer to watch the Perseids. So we stayed up… they did the best they could… stayed up to about 10 o’clock watching the Perseids. We were all sleeping outside, so we just fell asleep. I think I woke up about 2 in the morning, 3 in the morning, and that’s when you see the real show. So then it was just meteors, and the Milky Way was high overhead and just so vivid, so clear… it’s just amazing. So, if you go out and you think you’re seeing dark skies at like 11 o’clock, it’s nothing to what you see at like 2… 2 or 3 in the morning. And for all you poor suckers living in the cities….

Pamela: And I was one of those suckers for a lot of years… so I know your pain.

Fraser: Yeah, so what’s going on then… why is the view from the city so bad?

Pamela: Well, we’re dealing with two different problems. The biggest problem is that our atmosphere is pretty good at reflecting light, and if the light it’s reflecting down… the light that’s scattering in the atmosphere is greater than the amount of light coming down from the star… you’re never going to see the star. In cities, in rural areas with people with paranoid lighting schemes, there’s huge amounts of light that’s getting directed straight into the sky. When you go to archaeological sites, architecture sites, places with pretty buildings where all the buildings are illuminated, all of that light that isn’t landing directly on the building–it’s going straight up into the sky. And all of this light in our atmosphere on a cloudy night, it makes the clouds glow red, glow orange, glow white if you’re someplace with a lot of fluorescents, and all of that is skyward-directed light. If you actually go someplace dark–this really confused me the first time I saw it–the places on the sky that are darkest… that’s where the clouds are. I’m used to being from a city or suburbs with lots of light… you look up and oh, that bright orange thing is a cloud. No, in a dark site, the darkest places on the sky are the clouds. And in a truly dark site, the starlight is bright enough to read by, and a cloudy night is so dark you can’t walk.

Fraser: It’s interesting that you’re in the city and you can have like… even in a place with no streetlights, there’s still enough reflected light coming off of the clouds that everything is always sort of illuminated. And you don’t really appreciate how dark things can get until you are out in the wilderness or away from the lights, and now suddenly you just have the starlight and it is dark!

Pamela: Right, nothing’s quite as dark as a cloudy, cloudy night in a dark sky. And nothing’s quite as bright as a cloudy, cloudy night in a light-polluted city.

Fraser: So you’ve got the illumination from the city being sent upward, and then it’s bouncing off either clouds, or even just the atmosphere itself.

Pamela: Yeah. The other one… well, our own eyes have to dark-adapt. If you’re inside in a bright kitchen, for instance…. you have a farmhouse and a really dark site… you’re good to the environment so you have really good blinds and curtains both up to make sure that no scattered light gets out your window, and you’re hanging out in the kitchen making hot cocoa before you go out to go observing, then you step outside into the pitch darkness of your farm country home and you look up…. and you don’t see a thing. You have to wait for your eyes to dark adapt. Now the thing is, is if you’re someplace where you have your neighbor’s security light within your line of sight, you’re someplace where you have streetlights within your line of sight… that’s what I had growing up, I would go out to observe in the driveway but we had streetlights because I lived in the suburbs with sidewalks and lots of safety stuff. And all of the streetlights, the second your eye catches them… your eyes… they constrict and now suddenly your eyes aren’t sensitive enough to see the faint stars. So there’s a lot of places that if you could just somehow stick yourself in the bottom of a well–a very short well so you could easily climb back out–by not having any lights within your peripheral vision, you’re suddenly able to see far more stars. And even though it’s not safe, if you’re in a city, the best place to go observing is down that dark spooky alley where there’s no windows facing the alley. And from that dark scary alley you’ll be able to make out the stars between the buildings.

Fraser: So let’s say that you live in a city with bright lights, bright skies, and you want to truly appreciate dark skies, you want to see the Milky Way for the first time… what do you have to do?

Pamela: Well, the easiest thing to do is look at a map, find the nearest completely empty space, and drive there. You need to find someplace where there’s just not humans around. And a lot of times you don’t have to go very far. From Austin, Texas we’d go up to a state park called Canyon of the Eagles. It was a nice large park and there was an observatory in the center, and from a lot of the different camp sites you can still get really dark skies… you just have more trees when you’re in the camp sites. Find that nearby park, and there’s also a lot of places called starlight reserves, dark sky parks, which are large areas of acreage that are set aside specifically to try and keep a place where future generations can go out and see the stars that are disappearing one by one to the people who live in communities.

Fraser: Yeah, in Vancouver there’s a dark sky park out in the Fraser Valley, sort of out by a town called Abbotsford, and I’ve been out there a couple of times. It’s out of the city but then there’s a mountain that blocks… that’s right in between you and Vancouver. So a lot of the light coming from Vancouver is blocked off there, and it’s almost like when you come around the corner to the dark sky park, everything darkens much more and you can really see a beautiful night sky. There’s a great astronomical community that sets up telescopes there and you can go out and look through people’s scopes… it’s great. So, I know there’s a bunch of them in Canada… I’m sure there’s a bunch in the U.S., and even around the world. So if you could find your nearest dark sky park… but how far… let’s say you live in–I don’t know–Los Angeles… you know, how far north up into the Mohave, how far would you have to get before you could really start to see some dark skies?

Pamela: The dark, dark skies…. three hours out of a city is enough. McDonald Observatory, which is one of the darkest sites in North America, is located 3 hours from El Paso, 3 hours from Odessa, and it’s a boring, boring, boring drive… but that drive’s worth it. It’s basically the edge of an equilateral triangle from these two cities and there is often the horizon… you do see some light… Ft. Stockton’s out there, but more importantly, there’s some little retirement communities cropping up on the sides of the mountains, but those 3 hours are enough to get some of the nicest skies in the United States.

Fraser: Yeah, so even 1-2 hours out of a town… 3 hours if you can find a really dark place… you know go camping…

Pamela: One of the easiest ways to find a bunch of really nice dark sky sites is find out where the astronomy clubs are meeting. There’s all over the place different star parties run by different regional and national organizations. There’s the Texas Star Party, there’s Stellafane, there’s the Winter Star Party that’s held out in the Florida Keys. Look for these lists of star parties, and then look to see where they’re located, and those are the places that you want to go.

Fraser: Is there a direction you want to head? Is it better to head north or south, east or west?

Pamela: It depends on what you’re trying to look at. So for instance, if you know there’s some specific comet… there’s not any really interesting ones right now, but should, when you’re listening to the show, there’s some awesome comet in the sky… if you’re in a city–figure out what direction is the comet in, and drive in a direction where the city is 180 degrees around the sky from you. So, say that there’s this amazing comet that’s in the north, well that means that you want to drive north from the city so that the city is behind you in the south, and the comet’s in front of you in the darker part of the sky in the north.

Fraser: Right, and I guess it depends if you’re trying to see something near sunrise or sunset?

Pamela: Right. So there, if you’re trying to find something that’s rising right before sunrise, well that’s something that’s going to be up in the east so head east out of the city and leave the city behind you in the west.

Fraser: Right, that way you have the best chance to see it rising up.

Pamela: Exactly.

Fraser: Then what other things… if you want to adapt your eyes–how long are you looking at? What are some good ways to do that?

Pamela: In general, 20 minutes is the right amount of time to get your eyes fully adapted. They’ll keep getting a little bit better after that, but 20 minutes is enough to get most of the way there. And even after 5 or 10 minutes, you start to see amazing differences. Any of you who’ve had a spouse turn the light on and off on you after you’ve gone to bed, know the “oh, God, I’m blind!” moment followed by the a few minutes later…. oh, I’m fine again, just looking at random light coming in through your bedroom window. It helps not to drink caffeine… it also can affect things. So basically look for chemicals that won’t cause your eyes to act in funny ways. So basic common sense… And keep yourself well-hydrated… that always helps everything.

Fraser: Let’s say you’ve got your eyes adapted, what can you do to protect them? Like if you’re trying to…. people turning on lights… things like that…

Pamela: Right. So, star charts are all of our friends… I admit I use them all the time and computers with star charts also exist. The thing you don’t want to expose your eyes to is light that’s white or blue, or any color other than nice deep red. What people most often do, is that they get sheets of red cellophane and they coat all of their flashlights, they coat their computer screens. A lot of software has night-sky viewing modes that will take over your whole computer, so if you’re using some of the software… Bisque software… it has a night-sky mode such that when you open Excel, Excel will still have deep-red background with black letters on top of it. This will help protect your eyes. Flashlights, of course… I actually go the extra step further because red cellophane can come off no matter what amount of duct tape you use… you can puncture it… some mistake can happen. Red nail polish–you may be a guy and you may feel weird buying the red nail polish, but painting red nail polish on the front of your flashlight… try one coat… turn your flashlight on. Try 2 coats… it’s a good way to get the precise amount of shielding that you need that allows you to just barely make out what your star chart says.

Fraser: That’s a good idea. And that does the trick… you’ve done that…

Pamela: Yeah, it works perfectly.

Fraser: Because I… often you can get from like army surplus stores… they have these army flashlights and they’ve got a whole bunch of different filters you can stick in front of the flashlight… you unscrew the front and stick in a red filter and screw it back in, and those are pretty good. But I can almost imagine that they’re not dark enough… like they’re dark enough if you’re trying to sneak through the forest with your comrades, but maybe not dark enough if you’re trying to make sure that your eyes are perfectly… stay dark… oriented to the darkness. So you may want to take one of those and even, as you said, put more nail polish on it to even darken it further. That’s a really good trick.

Pamela: And Maglite also has those filters and they’re not bad, so if you’re doing a public event where you’re still going to want to use the red flashlights, but you know that there’s going to be people with car headlights now and then… it’s a cheap option that doesn’t require the humiliation of going to the nail polish section. But, there’s other things that you have to be aware of, especially if you’re doing star parties and you’re with a bunch of dark-sky friends and it’s not open to the public… closed… you’re there to observe. Parking lights on cars are evil. I actually had a student… he was awesome… he popped the fuses for his car’s lights because he had daytime running lights, he had back-up lights, and he had parking lights, and they’d all randomly turn themselves on and off and he’d just pop the fuses for them… put the fuses back in when he got out of the dark sky site. It worked. It was slightly insane… I think he drove with his door open so that he could keep the car going along the little line on the side of the road… but it worked.

Fraser: Right, and even just opening up your car…. the dome light comes on… arrgghhh! It’s a bright white light and boom–your eyes are wrecked.

Pamela: And laptops…

Fraser: Yeah, open one of those up… or even like a cell phone will get ya…

Pamela: And the problem that you have to worry about now… and this is where duct tape becomes your friend… or electrical tape also works really well and comes off easier… is my Mac has a heartbeat, and there’s the little green light on the power supply… and so all the things that would annoy you in a hotel room are way worse when you’re at a star party trying to protect your eyes while trying to use your computer.

Fraser: And I guess, then, the last thing that we wanted to talk about today is the battle… the fight to keep the skies dark and to get them back to some kind of semblance of darkness. So, what can cities do to stop polluting the skies?

Pamela: This is really the central issue. We spend somewhere between 1 and 2 billion dollars a year on light where the photons are going into the sky instead of onto the ground here in the United States. And that’s a lot of money! That is 1/20 of NASA’s budget… somewhere between 1/10 and 1/20 of NASA’s budget… I’d love to see that money instead go into research, go into feeding people, going into all sorts of other programs, but no… it’s going into illuminating things for astronauts. The best thing you can do is figure out what are your lights actually lighting up and then replacing them with lights that light up what you meant to light up. The most egregious form of light is the nice historic pretty ones where you have a pole, and you have at the very top of the pole a light–usually in a globe… and the majority of the light is going straight up into the sky… and there’s actually a shadow cast around the base of the pole. So, if you’re walking along at night through a park that’s lit up with these nice pretty historic-looking lights, a mugger standing up against the base of the pole would be really hard to see, and you also end up with these circles of darkness with these larger circles of kind of brightness around them, and the trees are really nicely illuminated… and I’m not worried about attack by squirrel in the middle of the night… by getting lights where you have the lights on little arms and all of the light being pointed straight down like a lot of parking lots have… those are much better. You want to replace incandescent bulbs with LEDs or fluorescent bulbs. LEDs are in many ways the most cost-effective way to go because they take so little energy, and you have to replace them–but very very infrequently.

Fraser: Right. And they’re throwing out photons in a nice straight line from wherever they’re being emitted. It’s not like a… something that’s being heated up… a coil or a circle and the light just coming out in every direction.

Pamela: Yes… so just a plane panel of LEDs… it’s low-cost in terms of longevity. It’ll cost a lot more to set up initially, and I know at the end of the day you have to worry about how much money do I have this month, not how much money do I have in the next 3 years, but once you’ve made that initial investment, you’re protecting the sky.

Fraser: Well, I actually found that Walmart is selling LED lights now… like light bulbs….

Pamela: Really?

Fraser: Yeah, I just bought a bunch a couple a weeks ago. I went to Walmart and they have a whole big wall of the fluorescent ones, and then they also have a bunch of LED lights, and these will fit into your light bulb socket… and they use 4 Watts, or 1 Watt… it’s quite amazing. Now they’re not very bright, they’re definitely not a replacement, but like, for example, for the kids… I give the kids… they both have LED lights for their rooms and they just read with those lights, and if they forget to turn them off, it’s no big deal because they’re just sipping power. But outside… same deal. You put one outside and you can illuminate an area so you can not trip over your front steps but you’re definitely not wasting energy and not firing lights up into the air. Yeah… check out Walmart… you’d be amazed at what they’ve got now in terms of LED lighting.

Pamela: That’s cool. See we replaced all of the lightbulbs in our house with compact fluorescents and we just haven’t had a bulb go out… So in three years….

Fraser: Yeah, well that’s so… you know, that’s so “two years ago.” Now it’s all LED so…

Pamela: Yeah, we bought our house 3 years ago, so we’re all “three years ago.” That’s awesome, and protecting dark skies has so many different consequences. We’ve found that human beings… that if you’re in a brightly-lit bedroom, you’re not going to sleep as well as you would if you were someplace completely dark, so that streetlight outside your window that’s illuminating inside your bedroom instead of on the sidewalk, that’s a health hazard to you. Migrating birds get confused by all of these bright lights. Moths… we have problems with our ecosystem because things eat moths and moths are attracted to lights so the things that aren’t near the lights that would like to eat the moths are in trouble. The moths aren’t finding each other to reproduce, and lightning bugs can’t see each other anymore… imagine you’re a poor innocent lightning bug and you’re flying around in someone’s well-lit front yard at night and you can’t find your buddies. There are all these things that we just don’t think about. Sea turtles everyone knows about, but the lightning bugs… it’s so obvious in some ways and yet so easily forgotten.

Fraser: So, you know, take responsibility. Swap out your big flood lights and your bulb lights for things that are a lot more directional… things that can just cast a beam down to the places you want illuminated outside. And really, you know, does it really matter to have some corner of your property illuminated?

Pamela: Yeah, does the frog really want to be lit up at night? And, use motion-sensitive lights. If you’re worried about crime… it’ll light up for every single one of the neighbor’s cats… I guarantee it, but that’s ok.

Fraser: And then you want to take things to another… to a higher level and nag your city. Right?

Pamela: Yeah. And there’re lots of organizations out there to help you. The International Dark Sky Association is there. There’s an IYA Cornerstone Project–Dark Skies Awareness. And there’re people that are documenting how bad it is in different places. Globe at Night and the World Wide Star Count are two projects… Globe at Night occurs roughly every March and the Great World Wide Star Count occurs roughly every October. This year it’ll be October 9th – 23rd in 2009.

Fraser: Right, and that’s coming up, so if you want to get involved… chart your crappy skies… this is your chance.

Pamela: And both of these sites… they give you star charts and they send you out and they’re like… ok, what can you see? Tell us! And then you can use this data to go into your community. And if you want to be really qualitative quantitative [ed.], there’s an instrument called a dark sky meter that you can take around to different sites in your town and measure how much light there is in the sky, and say… look, there’s this one rural neighborhood that has no city street lights, and it’s really dark skies… and look, the crime rate is low. Here’s this other place that has the same low crime rate but it’s filled with street lights, all the houses are illuminated because they’re big and fancy, but the little kids living there can’t see the stars.

Fraser: Right. And this is the… I’ve heard that this is a bit of a fallacy… that criminals like bright city lights as much as anyone because that lets them see what they’re doing.

Pamela: Exactly. I can’t even stick my key in my doorknob at home… how can you pick the lock if you can’t see it?

Fraser: Yeah, exactly… so that doesn’t necessarily make sense. So there are a bunch of organizations that you can get involved with who are trying to battle to get these better lighting systems put into cities. There are groups that will help you get involved sort of at a scientific level to chart the state of the skies right now. So, there are a lot of ways to get involved. So, I think for both of us… if you haven’t seen the Milky Way with your own eyes….I mean we’ve already nagged you about Saturn… see Saturn in a telescope! But if you haven’t seen the Milky Way with your own eyeballs, organize a trip with your buddies… get out into the wilderness and see the Milky Way. Get up at four in the morning and go outside…

Pamela: And those of you in the southern hemisphere, you’re losing the Magellanic Clouds, too, and that’s just wrong, those are cool!

Fraser: Yeah… I’ve never seen those. Alright, well thank you very much Pamela, and so hopefully next week will be the DragonCon episode, and then back on to our regular shows. So we’ll talk to you… whenever we talk to you next!

Pamela: Ok, sounds great Fraser… I’ll talk to you later.

Fraser: Bye.

Pamela: Bye-bye.

This transcript is not an exact match to the audio file. It has been edited for clarity.