Ep. 575: Observing the Moon

As amateur astronomers, we curse the Moon every month. Seriously, why doesn’t someone get rid of that thing? This week, something occurred to us. What if we actually pointed our telescopes at the Moon? What would we see?

Download MP3 | Show Notes | Transcript

Show Notes

Annular solar eclipse 21 June 2020 (timeanddate.com)

Phases of the moon (timeanddate.com)

What is earthshine? (Earthsky.org)

Directory of craters (USGS)

Lunar crater observations (Lunar and Planetary Institute)

What is Lunar Regolith? (Universe Today)

Surface Properties of the Moon (Dr. Eric Blackman, University of Rochester)

Geologic map of the Moon (USGS)

Copernicus crater (NASA)

How to See All Six Apollo Moon Landing Sites (Sky & Telescope)

Video: “Full Moon Silhouettes” (Mark Gee)

Mystery of the moon’s tilted orbit (Earthsky.org)

Penumbral lunar eclipse (timeanddate.com)

Video: “What determines when we have an eclipse?” (NASA Goddard)


Transcriptions provided by GMR Transcription Services

Fraser Cain:                 Astronomy Cast Episode 575: Observing the Moon. Welcome to Astronomy Cast – your weekly facts, space andjourney through the cosmos where we help you understand not only what we know, but how we know what we know. I’m Fraser Cain, publisher of “Universe Today.” With me as always is Dr. Pamela Gay:, a senior scientist for The Planetary Science Institute and the director of CosmoQuest. Hey Pamela, how’re you doing?

Dr. Pamela Gay:         I’m doing well. How are you doing this fine night before summer solstice?

Fraser Cain:                 I know, I know. I’ve gotta say, we’ve been doing the virtual star parties and they’ve been having to go later and later and later. And so now we have to start at 9:00. It’s going to be nice that nighttime comes earlier now. We’ll talk a bit about this next week a bit about the things you’ll be able to see in the nice, warm summer nighttime sky in the northern hemisphere. But as you probably know, this is gonna be our – this is our penultimate episode for season – we were doing the math beforehand. What did we say? Season 14?

Dr. Pamela Gay:         We think it’s season 14.

Fraser Cain:                 We think we’re on season 14 of Astronomy Cast. So, we start up again in September. Typically, we used to start with whatever interview Pamela would do at Dragon Con, but I don’t think that’s gonna be happening this year.

Dr. Pamela Gay:         No, not so much. Not so much.

Fraser Cain:                 Yeah. So, we will be picking up again in two months. So, this episode, next week’s episode, and then we start back up. But one thing I just want to promote – if you haven’t already – is, you should sign up to my weekly email/newsletter that I write every week. In fact, I’m in the midst of writing it right now. I send it out on Friday mornings and it has got 12 to 20 stories in it, links to dozens of other interesting stories, great pictures, astrophotography. It is a one stop shop for every piece of space news that’s happened this week that I find interesting. So, you should go to universetoday.com/newsletter to sign up.

                                    It’s totally free. There’s no ads. It’s just Fraser’s random musings on what’s happening in space and astronomy.

Dr. Pamela Gay:         It’s awesome. You want it. And when he calls it a newsletter, he’s lying. It’s more like a magazine.

Fraser Cain:                 Yeah, it’s a magazine.

Dr. Pamela Gay:         It’s a lot.

Fraser Cain:                 It’s a novella. Yeah. Yeah. Each one is about – yeah, I’d probably say it’s about 15,000 words that I write once a week.

Dr. Pamela Gay:         Yeah.

Fraser Cain:                 Yeah. Is that right? No. Not that many words. 5,000. It’s probably 5,000 words. All right. As amateur astronomers, we curse the moon every month. Seriously. Why doesn’t someone get rid of that thing? This week, something occurred to us. What if we actually pointed our telescopes at the moon? What would we see? Yeah, I hate the moon. Because half of the month, for goodly portions, you look up at the moon, and there’s – you look up at the sky – and all you see is the sky glowing because of the stupid moon. But –

Dr. Pamela Gay:         You just need to pick your times better.

Fraser Cain:                 Yeah, exactly. Pick my – only look at space for two weeks when the moon is below the horizon. The times when it’s not raining here on the west coast, which, face it, that’s all the time. Yeah. Yeah, pick your times better. Fine.

Dr. Pamela Gay:         So –

Fraser Cain:                 Well, let’s look at the moon.

Dr. Pamela Gay:         So, the moon has this habit of orbiting the planet, which is better than colliding into the planet or something. And this means that yes, it is up half the month, but the time of day that it’s up changes constantly. We are recording this on Juneteenth, June 19th. Tomorrow, midnight here, in the Americas – Sunday morning in Central Africa, the Middle East and Southeast Asia – there is going to be a solar eclipse.

Fraser Cain:                 Yeah.

Dr. Pamela Gay:         And that means the moon is new and not visible at all.

Fraser Cain:                 Right.

Dr. Pamela Gay:         It is –

Fraser Cain:                 So, the irony of this episode is that we’re talking about observing the moon at a time when the moon can’t be seen.

Dr. Pamela Gay:         But it also gives us a glorious chance to remind everyone of how it is that folks like me remember the moon is going to rise and set. So, when there’s a solar eclipse, the moon is generally going to be rising the exact same time as the sun, roughly 6:00a.m. Setting the same time as the sun, roughly 6:00p.m., ignoring the fact our planet is tilted and things like that.

Fraser Cain:                 Okay. But New Moon is a good time for a fresh start, right?

Dr. Pamela Gay:         Exactly.

Fraser Cain:                 That’s a good time to start observing the moon as you move through the cycles of the moon and it’s pretty amazing how many interesting things there are to see and how it looks different as it moves through all of its phases.

Dr. Pamela Gay:         Now, as the moon starts migrating towards full, it’s going to be rising 45 minutes later every day. This means that what is 6:00a.m. tomorrow will be 6:45 the next day; will be 7:30 the next. And as it rises a little bit later and a little bit later, it’s expanding its angle away from the sun on the sky, until eventually you get to the point that the sun and the moon form a right angle. And what we see in the sky is a first quarter moon. The first quarter moon is rising at noon, quarter turn of the earth away from sunrise, and we only see half of the face of the moon illuminated. And it’s called a first quarter because the moon is a three-dimensional object.

Fraser Cain:                 Okay, right. So, even though it looks you’re seeing only half the moon, you’re actually only seeing a quarter of the moon illuminated from your perspective.

Dr. Pamela Gay:         Exactly. I have gotten that wrong on an exam when I was a student and I will never forget it.

Fraser Cain:                 Right. But the quarter is a very dramatic time to see the moon, but I know there’s a lot of amateur astronomers who will start chasing the moon moments after the moon has passed as its closest time to the sun. And it depends on how far it is above and below. In this case, it’s passing right in between the sun and the earth, but there are times when within a day, you can start to see the tiny, thin little crescent of the moon and even start making your observations of the moon then.

Dr. Pamela Gay:         And this is important in many different Muslim cultures where they’re still using the first sighting of a moon afternoon to mark the starts of their various months and their various holidays. So, if you’re waiting for a holiday that involves fasting during daylight to end, you’re very interested in that lunar phase.

Fraser Cain:                 Right. And it is pretty amazing – and I think, depending on how good of a view you have to the east – no, yeah – sets in the west – so, how good of a view in the west. You get that first night when you see that really thin crescent moon after the sun has gone down. And it was there all along – it’s only when the sun’s gone down, it is actually visible and easy to see. And it just – it’s one of the most beautiful times to look at the moon in a small telescope because you’re getting these extreme shadows on the surface of the moon showing you just a tiny little hint of what’s to come.

Dr. Pamela Gay:         And one of the awesome things that we encourage all of you to do is to take advantage of the fact that you’re listening to this, hopefully when most of you are just barely starting to be able to see that crescent moon at sunset. Now, what we encourage you to do is to go out at sunset every night that’s clear and not raining and see if you can find the moon and spot the fact that it’s in a different place.

Fraser Cain:                 Yes. At the same time, yeah.

Dr. Pamela Gay:         And its phase is radically changing. A lot of people will just somehow be oblivious to the fact that the moon is actually up during daylight – that that first quarter rising at noon – it means it’s around all afternoon with you.

Fraser Cain:                 Yeah. I find I get sort of refreshed – reminded of the moon once a month. Because you get that first night where you get that thin little crescent moon, and then the next night, the moon is a thicker crescent and it’s a little bit higher in the sky than it was the night before. And each night it goes, you see that until it moves to that quarter moon that you were mentioning. And often, that will take –  you’ll have about five-ish nights I find where it moves up to that quarter moon that you’re more aware of every night; especially if you have five clear nights in a row where the night is – you don’t have clouds and stuff, so you can kind of just go out the same time, and there it is.

                                    And especially when you’ve got something bright like Venus or Jupiter in the sky in roughly in the same location as well, because now you’ve got a vantage point. You go, “Oh, it’s much farther from Venus than it was the night before.”

Dr. Pamela Gay:         And one of the awesome things that you can do as you’re watching through the month the behaviors of the moon is, you’ll eventually be able to see that full moon rising on the horizon. And the summertime is the perfect time to learn how to photograph the moon on the horizon because with the daylight sky still visible, you have a pale moon against a still blue sky and that is so much easier to get right photographically than a full winter moon against a dark black sky. The contrast on that’s almost impossible to capture.

Fraser Cain:                 Now, you’re jumping around the timeline here. So, as we – and we’ll get to the full moon. But for now, what kinds of things – either just with your eyes or with a telescope – are you gonna be wanting to see in the phases leading up to that first quarter? What are the advantages of observing at that point?

Dr. Pamela Gay:         So, one of the most amazing things to do when you still have that slender, slender crescent is you can see the daylight side of the moon as that brightness, but you can also see the nighttime part of the moon illuminated by earthshine.

Fraser Cain:                 Right.

Dr. Pamela Gay:         And the fact that you can see both parts simultaneously is something we don’t usually think about, but the second you try to take a photo of it, it becomes unavoidable. It’s just there throwing off your camera’s ability to figure out how long it should keep the shutter open. Our earth is enough light scattered off of it to change how we see the moon.

Fraser Cain:                 Yeah. And I know that astronomers are actually thinking of using similar systems – that if you could see the earthshine reflected, or the planetshine reflected on the moon – you would actually be able to learn a lot about the planet itself. You can actually see where there are oceans; where there are weather patterns, continents, etc. just by the way the light is reflecting off the planet onto the moon. So, if you were able to observe moons around other planets or around other stars, you could learn a tremendous amount about the planet itself because of that shine.

                                    The thing that I think a lot of people don’t realize is that the shadows on the moon are constantly changing. And so, as we get to that quarter moon, that’s when you see large portions – essentially, the craters are in some of the best relief, as opposed to, say, looking during a full moon.

Dr. Pamela Gay:         And there’s terminology that I’m gonna bring up here, because it’ll make the rest of this conversation easier. The brightly illuminated part of the moon – that’s the daytime. The dark part is the nighttime. And that line that separates the day from the night is called the terminator. And as you get closer and closer to the terminator, the shadows get longer and longer and longer. So, when we’re looking at the crescent moon, we’re seeing pretty much just shadows and light. That’s it. As the terminator comes closer towards the center, we’re starting the see the sun hitting directly on the edge of the moon.

So, the shadows get shorter as we get closer to the edge of the moon, and the longest shadows are in this long stripe that we’re looking straight down on in the center part of the moon.

Fraser Cain:                 And think about that. You’re here on earth – just before sunset, the sun is low in the sky and the shadows are really long. You see these big, long shadows. And of course, when you’re a photographer and you wanna take pictures of beautiful mountains, it’s called the golden hour. That’s when you take pictures because you get these really long shadows that will show all of the features in this really highlighted way. And it’s the same thing. When you’re looking at the moon through a telescope – through binoculars – on the one side that is in full illumination, everything is completely sort of his face-on and you don’t get that structure.

                                    But then right along the terminator, you did get much longer shadows. And what’s amazing is that over the course of this month as the terminator moves, different parts of the moon are illuminated at different points.

Dr. Pamela Gay:         And the areas of the moon that we’re seeing where the sun is primarily going straight down, that allows us to see the natural color contrasts between the bright white regolith and the darker grey mare of the moon – the two different mineral compositions that we see on the surface. But the places that have those long, sprawling shadows – that really allows us to see where are the craters and where are the hills, mountains, and volcanos?

Fraser Cain:                 Yeah.

Dr. Pamela Gay:         The moon is geologically diverse in its shapes, and to see that, we really need to see the shadows.

Fraser Cain:                 And so, if you’re wanting to do astrophotography of the moon, and you wanna take the best possible picture of any crater – any feature on the moon – you have to figure out when the terminator is going to be as close as possible to that feature. And that changes day by day, even hour by hour depending on how sort of high resolution – how close, how much magnification you’re trying to bring into your image. So, there’s actually a lot – as an astronomer, you will want to take pictures of different regions of the moon on different days, and you actually wanna plan this out. Today, I’m gonna go after Copernicus. Today, I’m gonna go after the Apollo landing site. And you just know.

                                    And there’s a lot of interesting features that’re revealed, like there’s the Lunar X, and you can only see it on a couple of days when the shadows are just right; feels like Indiana Jones, kind of.

Dr. Pamela Gay:         And the short summer nights aren’t best for this, but during the winter, you can actually go out and start your night with a nice quarter moon rising, take a look along the terminator, go observe a bunch of other objects, come back and see the moon’s shadows slowly change over time as more and more things come out of shadow and come into the light.

Fraser Cain:                 So, now we shift into that next portion where we go from the quarter moon to the full moon. What’s that called?

Dr. Pamela Gay:         That’s the gibbous moon.

Fraser Cain:                 Less interesting, although I find visually it starts to look just like a full moon to me. But the terminator is continuing to move across the moon and illuminate other chunks of the moon that you can see.

Dr. Pamela Gay:         And for whatever reason, a lot of people just find the gibbous moon less satisfying. I can’t really explain it. It’s just like, “Crescent is awesome. First quarter, meh. Gibbous – who cares?”

Fraser Cain:                 Yeah. Who cares? Yeah.

Dr. Pamela Gay:         But that full moon. It leads to all sorts of – I don’t wanna say myths, but optical illusion, and just awesome photography.

Fraser Cain:                 Yeah, so you were talking before about being able to take a really amazing picture of the moon as its rising down by the horizon. And of course, I think we’ve all experienced that – that moon horizon illusion, that it looks like, “Look how big the moon is!” just as it rises. What’s going on there?

Dr. Pamela Gay:         It’s just psychology. Our brain, when the moon is high up in the sky, lacks anything to tell us how big or how small it is. And so, in the vastness in the space, our brain is like, “Moon is small.”

Fraser Cain:                 Look at that little moon. Yeah.

Dr. Pamela Gay:         That little tiny moon. But when the moon is low on the horizon, our brain is able to say, “It’s bigger than that tree over there!” And our brain is right. On the sky, it does appear bigger than that tree, but that doesn’t mean it’s actually bigger than it is straight overhead. And you can learn this by – or prove this – by going out when the full moon is rising and stick your thumbnail, stick your pinky – figure out what fits best –

Fraser Cain:                 Yeah, it works with the pinky.

Dr. Pamela Gay:         Yeah – over the surface of the moon, and then wait for it to get higher in the sky, and you’ll find it’s still the same finger that covers the moon.

Fraser Cain:                 Yeah. And if you want an even more accurate thing, take a small – like an aspirin-size pill – and then hold that out at arm’s length, and you should – same thing – the pill should just perfectly cover the moon. And then, try that when the moon is down at the horizon and try that again when the moon is really high. And you’ve seen some amazing pictures where people take a picture of the moon every couple of minutes and so you get these little circles that move up, and the moon stays precisely the same size the whole way up. It is not changing in size. It is all in your mind, and yet –

Dr. Pamela Gay:         It’s entirely in your mind. Yeah.

Fraser Cain:                 – I’m fooled by it every time. I never can just rationally go, “Oh yeah, the moon is small, just like it always is.” It looks huge.

Dr. Pamela Gay:         It really does. And there are photos out there that make this illusion even greater by using massive telephoto lenses.

Fraser Cain:                 Yes.

Dr. Pamela Gay:         So, if you can get a good distance from a building, a park, a cliff – something you know the moon is going to rise behind – and zoom in on it, you can catch a building because it’s so far away appearing smaller than the moon on the horizon and get these amazing shots of essentially the moon dwarfing historical places, barns. There’s some amazing videos out on the internet. One of my favorite shows people at a park just basically going about their business as silhouettes in front of the moon.

Fraser Cain:                 And there are some great apps you can use to calculate where the moon is going to be for this, and for you to calculate where you should go to be able to go to capture this image. But you can also do this – go out to a park sometime if you wanna try and capture one of these images the night before the full moon. Run through – wait for the moon to rise. It’s gonna rise a little earlier than the next night. And then you can set everything up and make sure you’ve got it, and then the next night, do that. Another great experiment that you can do if you wanna observe the moon – because the full moon, it’s kinda boring to take a picture of.

                                    You get interesting coloration on the surface, but you don’t get those craters because there’s no terminator, so there’s no shadows. It’s just straight-on moon. But you can take pictures – take a picture one month where you absolutely lock down how far you’re zooming, the direction your camera is pointing, exactly everything the same. And then, a month later, take another picture – hopefully you get clear skies – of the moon, and then a month later, do another one. And then, when you compare these different images and stack them on top of each other, the moon will be different sizes.

Dr. Pamela Gay:         And the other thing you have to watch out for when doing that though is the moon does wobble a bit. It doesn’t actually wobble. Its orbit changes enough month to month that exactly where on the horizon it’s rising and setting is going to vary.

Fraser Cain:                 Yes.

Dr. Pamela Gay:         I have made the mistake of lining my camera up on the wrong silo in the distance, so don’t be me. Learn from my mistakes.

Fraser Cain:                 Right, right, right. And it goes back to that idea that we get these lunar eclipses and solar eclipses because every – it takes a few months. And sometimes the moon is above the plane of the ecliptic – in between the earth and the sun – and then other times, the sun is below in between the earth and the sun. And then, every now and then the moon is directly between the earth and the sun. And so, where that moon is going to appear on your horizon depends on which way we are. And you can actually – you could practice starting to predict when you’re gonna see these eclipses because you can see the moon moving closer and closer each night – each month – from the point that it’s rising until it lines up.

                                    Of course, you also have to balance that with the tilts of the earth, and as the seasons themselves change, etc. But you can get a sense of when the moon and the earth and the sun are all gonna line up and we’re gonna get that lunar eclipse, solar eclipse, somewhere on Earth.

Dr. Pamela Gay:         And lunar eclipses and solar eclipses generally come in groups. We have a solar eclipse tomorrow for some parts of the planet. Unfortunately, this is a really cruddy alignment. So, it’s not a total solar eclipse. It’s what’s called an annular eclipse where the moon is sufficiently far away from the earth that it appears smaller than the sun on the sky.

And it’s also about as bad an alignment as you can get and still get an eclipse because instead of getting that perfect what’s called an umbral lunar eclipse when the moon passes through the darkest part of the earth’s shadow – we had earlier this month and we’ll have 4th of July weekend – what’s called penumbral eclipse, which is when the moon just gets slightly dimmer because it goes through the outer part of the earth’s shadow and it’s not very exciting.

Fraser Cain:                 Yeah, very boring.

Dr. Pamela Gay:         Yeah.

Fraser Cain:                 Yeah. So, as the moon continues to shift through its phases, what’s the next phase?

Dr. Pamela Gay:         Well, third quarter, when we’re seeing the illuminative part of the moon has shifted around again.

Fraser Cain:                 And what do you call a moon that is starting to shift from full moon to new moon?

Dr. Pamela Gay:         I always get made fun of for this because I learned how to say this before –

Fraser Cain:                 By reading it. Yeah.

Dr. Pamela Gay:         Yeah.

Fraser Cain:                 Yeah, it’s a waning moon. Here, let me prompt you. It’s a waning moon.

Dr. Pamela Gay:         So, for those of you who haven’t heard, I made the mistake a while back of saying wanning, because that’s what I read –

Fraser Cain:                 Or whanning? Yeah, wanning? Yeah.

Dr. Pamela Gay:         – when I was a small child. And no, I was wrong. So now, now I just avoid the word – just avoid it completely.

Fraser Cain:                 Yeah, the moon waxes and wanes. I love it.

Dr. Pamela Gay:         And here is when you can get back to observing in the early evening. So, with the full moon, we have the full moon rising at – again, ignoring planetary tilt and seasons – the moon rising roughly at 6:00p.m., setting at roughly 6:00a.m., being straight overhead at midnight. That’s the glorious thing about the full moon is it’s with you the entire night. It’s always the annoying thing about the full moon.

Fraser Cain:                 Yeah, what do you mean? The moon could show up and it could just get lost and let us look at everything else in the night sky. But no, it’s there for the whole night. So, the only thing that’s nice about the waning moon is that it shows up 45 minutes later every day.

Dr. Pamela Gay:         Exactly.

Fraser Cain:                 And so, you can start observing, and the moon isn’t up, and then you can observe for a little longer and the moon isn’t up. And then eventually, finally, the moon shows up to ruin your party.

Dr. Pamela Gay:         And so, when you get to that third quarter moon, it’s rising at midnight. So, first quarter is noon, third quarter is midnight, and that’s the phase of the moon that you have happily at sunrise and joining you until noon the next day. Now, this starts to get at how we can tell if we’re looking at a waxing or a waning crescent. Do you know this trick of the horns?

Fraser Cain:                 The horns? No. The horns point towards what?

Dr. Pamela Gay:         So, when you have a crescent moon on the horizon and there’s no sun, you’ll see the fat, illuminated part of the moon pointed roughly towards the ground, the two horns of the crescent facing up, and the illuminated part always faces towards where the sun is.

Fraser Cain:                 Right.

Dr. Pamela Gay:         So, if the sun isn’t visible, that means that the sun has already set and that illuminated part that you’re seeing, that is pointing towards sun, sun is below the horizon, and the horns are up. And yeah, it’s cool. Horns up.

Fraser Cain:                 Yeah, even with the quarter moon, but especially with that crescent moon, you see it absolutely, right? The sun goes down, and then the crescent moon is visible in the sky. And so, you can really – it’s perfectly pointed towards where the sun is. But I even think about that even more when you see a crescent moon – or even when you see a full moon. You see a full moon, and you just know the sun is behind you – that’s that where the sun is. And so you can – if you imagine the universe as this three-dimensional interaction between the earth, the sun and the moon, and you think of the moon not as this flat disc in the sky, but as this ball, and the way it’s being illuminated points the way towards where the sun is.

                                    You have just this moment where you realize just the geometry of everything involved. And from that point on, you can always find the sun – even though you can’t see the sun – just by looking at the moon. It’s such a neat idea.

Dr. Pamela Gay:         And you know the crescent will always be near the sun in the sky, and it’s just cool. I just like it.

Fraser Cain:                 And yeah, then over the course of the month, the night – as you said – quarter moon, third quarter moon is midnight-ish, and then it just keeps going through until the – and that’s often the time when you’ll see the moon during the day, I find, is because you’re seeing – either being a third quarter moon. And so, it is rising at, say, midnight, or even two in the morning – three in the morning. And then, you get up and it’s ten in the morning, eleven in the morning, and there’s the moon still pointing the way to the sun.

Dr. Pamela Gay:         It’s true.

Fraser Cain:                 Yeah.

Dr. Pamela Gay:         And exactly, I think when people see it just depends on where their sky is clear. So, for me, it’s because I spend a lot of time staring at my dogs in the yard, I’m much more likely to catch evening objects.

Fraser Cain:                 Right.

Dr. Pamela Gay:         So, I see that late afternoon first quarter during daylight.

Fraser Cain:                 Yeah, and you absolutely can see the moon during the day, no problem. And you can even look at it with a telescope, or a pair of binoculars. It’s pretty great. Obviously, be careful with the sun, but you can see features on the surface of the moon during the day, no problem. It’s that bright.

Dr. Pamela Gay:         And learning how to photograph the moon, I strongly recommend start by photographing it while it’s up against that bright blue sky. And then get darker and darker twilight as the seasons progress. Learn it now, and then have it mastered next winter so that you can finally figure out how to get the contrast just right against the nighttime sky.

Fraser Cain:                 So, it turns out the moon is okay and it’s fine. There’s some stuff you can do with the moon. It’s both interesting to look at during the day and at night, both in a telescope, binoculars, with your own eye, and it is fascinating to learn to take pictures of it both with a regular, widefield view, but also with brighter, telephoto lenses. All right. So, we won’t get rid of the moon just yet.

Dr. Pamela Gay:         We need it for other things as well.

Fraser Cain:                 Right. Of course. Of course.

Dr. Pamela Gay:         It’s good to have a moon around.

Fraser Cain:                 Yeah. Perfect. All right. Well, thanks Pamela. Do you have some names for us this week?

Dr. Pamela Gay:         I do. As always, we are brought to you by you. This show wouldn’t exist without your support at patreon.com/astronomycast. And I would like to thank Jordan Young, Barry Gallwin, Berko Roland, Ramji Anamathou, Andrew Palestra, David Troge, Brian Kegel, the Giant Nothing, Dan Litman, Steven Shewater, Laura Kettleson, Robert Palasma, Paul Jarmin, Joss Cunningham, Les Howard, Emily Patterson, Adam Anesbrowned, William Jones, Infinitesimal Ripple in Spacetime, Adlove Science, Gordon Dewey, Bill Hamilton, Sinai, Frank Trippin, Richard Riviera, Joshua Pearson, and Jack Mudge. Thank you all so much for all that you do that allows to do all that we do.

Fraser Cain:                 Thanks Pamela, and we’ll see you next week.

Dr. Pamela Gay:         Astronomy Cast is joint product of “Universe Today”, and The Planetary Science Institute. Astronomy Cast is released under a creative common’s attribution license. So, love it, share it, and remix it, but please, credit it to our hosts: Fraser Cain and Dr. Pamela Gay: You can get more information on today’s show topic on our website: astronomycast.com. This episode was brought to you thanks to our patrons on Patreon. If you want to help keep this show going, please consider joining our community at patreon.com/astronomycast. Not only do you help us pay our producers a fair wage, you also get special access to content right in your inbox and invites to online events.

                                    We are so grateful to all of you who have joined our Patreon community already. Anyways, keep looking up. This has been Astronomy Cast.

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Duration: 33 minutes