Can our Sun generate a solar flare that would wipe out life on Earth? Has the Large Hadron Collider answered any questions about the Higgs boson? And what would happen if you shined your flashlight out the front window of a spaceship going almost the speed of light?
If you’ve got a question for the Astronomy Cast team, please email it in to firstname.lastname@example.org and we’ll try to tackle it for a future show. Please include your location and a way to pronounce your name.
Can our sun generate a solar flare that could wipe out life on Earth?
Has the Large Hadron Collider answered any questions about the Higgs Boson?
What would happen if you shone a flashlight out the front window of a spaceship going near the speed of light?
Could a wormhole form in your brain?
Can’t we look in the opposite direction of the expansion of galaxies and determine the approximate center of the Universe?
Does the size of a star affect the speed/velocity/distance that a body requires to maintain a stable orbit around that star?
When a galaxy is found in the far reaches of the Universe, can astronomers figure out what is occupying that space today?
How does one become an astronaut?
How do scientists accurately account for Earth’s plate tectonics and other movements of Earth-based facilities?
If the Moon broke apart and became a rubble pile, would that change its gravity effect on Earth?
If the Universe is expanding, couldn’t it be older than we think?
Could interferometry be used in space?
Why are Saturn’s rings disappearing?
Download the transcript
Fraser Cain: More questions Pamela. Here come the questions.
Dr. Pamela Gay: These are always so frightening [Laughter] and so wonderful all at once.
Fraser: Can our sun generate a solar flare that would wipe out life on Earth? Has the Large Hadron Collider answered any questions about the Higgs-Boson? What would happen if you shined your flashlight at the front window of a spaceship going almost the speed of light?
Let’s get on with the first zinger – I mean question. Alejandro from North Caldwell, NJ asked a bit of a spoiler so I’ve kind of re-written the question so that nobody really knows what he’s talking about. Could the sun generate an enormous solar flare that kills all life on Earth?
Pamela: Present tense not so much; past tense yes.
Fraser: And how?
Pamela: [Laughter] When stars are young they go through this violent period of massive x-ray emissions and massive coronal mass ejections, flickering evil, ill-tempered nasty to your old type behavior. During that period of time nothing existed on the planet Earth.
Luckily stars settle down and start to behave and our sun is going to be a well-behaved star for awhile longer. While it will eventually destroy the Earth it won’t be through a giant enormous solar flare. It will more like just bake us unendingly until there is no water left.
Fraser: Right but not from a killer solar flare. Don’t you worry.
Pamela: Yeah the closest to a killer solar flare we can get nowadays is a really bad solar flare can take down the power grid. You can imagine if Canada or Siberia or any of the extreme north countries lost all of their power during the winter that could have terrible, terrible effects.
Without heat, people will die. That’s a secondary effect and you can always burn wood. It is something to be feared but we’re not going to have all life on Earth eradicated just potentially a few unfortunate people. That is something to worry about and something to work to protect ourselves from. Society itself is safe.
Fraser: If you want – I know we’ve interviewed Phil Plait with his “Death from the Skies” book – he’s got a chapter on that talking about solar flares and how they aren’t going to kill us all. Although as you said on some stars the solar flares can be quite impressive.
James Sagan asks: has the Hadron Collider given us any insight into whether or not the Higgs particle exists?
Fraser: Yeah, it is broken, isn’t it?
Pamela: Yeah this is one of the unfortunate things is they fired her up and something went boink and they shut her off. They’ve been in the process of trying to rebuild and rebuild and redesign some of the mechanisms in the process of rebuilding. They haven’t really gotten a full explosion, a full colliding of particles yet. They haven’t been able to look for the Higgs yet.
Fraser: When is the collider supposed to finally come back online?
Pamela: Sometime next year.
Fraser: Then finally, that would be like we’re in 2009 so sometime in 2010 we may finally know if the Higgs-Boson exists. Or we may find new and interesting ways that the collider can break itself. [Laughter]
Pamela: Fermi Lab is nipping at its heels and it could be that instead the U.S. Accelerator will get its new experiment going. We now have a race of the accelerators.
Fraser: Kate Neilson from Adelaide, Australia asks: if you were traveling in a spaceship that was going the speed of light and you’re standing in a window in the ship and had a flashlight in your hand and you turn on that flashlight out the front window what would happen?
Pamela: I’m going to momentarily ignore the fact that you can’t get things with mass going the speed of light.
Fraser: Right, in her question Kate said that if you had your spaceship going the speed of light and that’s not possible.
Pamela: That’s not possible, but even if you could if you’re chewing along through space at the speed of light time has now stopped for you.
Fraser: Time has no meaning.
Pamela: If time has stopped you can’t turn something on because that requires motion and time and there is no time so you can’t move that extra thing. You can’t actually turn on the flashlight.
Fraser: Okay so let’s say then that you can move at the speed of light [Laughter] and time does have meaning, what would happen to the flashlight that you’re firing out the front window?
Pamela: It would sit there going I’m a flashlight and I’m not going to do anything. The photons can’t move fast enough to get out of me.
Fraser: Right so the photons wouldn’t go anywhere. However I think maybe a more interesting question and is perfectly possible is if you made your spaceship go a fraction of a percentage slower than the speed of light.
Pamela: Yes, now we’re in a universe that makes sense.
Fraser: That makes sense. Let’s say that we use up all of the energy in the whole universe to accelerate our spaceship to almost the speed of light and then you walk up to the front window and turn on your flashlight. What happens?
Pamela: In this case time has slowed down for you so much that it looks just like what would normally happen when you turn on a flashlight. You see the beam shine. You’re not at all aware of how long it takes the beam to go from on to off to shining on distant wall.
Everything appears just like it appears when you’re walking around your house. As long as you’re chugging along at not the speed of light no matter how fast you’re going you’re always going to see the flashlight behave in the exact way.
Fraser: The trick is that people watching you do this somehow are going to see something different.
Pamela: To say you’re moving in slow motion, that’s an understatement. They’ll see that thumb flick that turns on the flashlight as taking years and years to transpire.
Fraser: When it actually works and the beam of light comes on it is going to go at light speed. You’re going to see it from outside. You’re going to see the light beam go exactly the normal speed.
It doesn’t matter that it is inside a spaceship that is already moving at close to the speed of light. It doesn’t matter. This is the whole trick with relativity.
Pamela: Yeah, it’s just the process of turning on the flashlight is excruciatingly boring to watch. Once it is on everything behaves normal no matter who the observer is.
Fraser: Let’s keep going. We have this question from Gopal from Fremont, California. He wants to know: can worm holes form inside the brain and if so would they be really small micro-nano-wormholes carrying bits of information?
Is that some kind of way that information can come into your brain from the universe? Alright let’s talk about what’s a wormhole?
Pamela: The idea of a wormhole is that it is possible to pinch space and time so that you essentially can grab the space over on this side of the universe, the space over on that side of the universe and pinch them together and tunnel through the topography of space.
Fraser: Theoretically possible, right?
Pamela: Theoretically. When you work these out using the geometry that we live in they turn out to be utterly unstable. They self-destruct instantly. You can’t construct one of these things that are stable, they just don’t work.
They’d also require in the case of this question microscopic black holes and white holes. The white holes don’t exist. Microscopic black holes if they did exist probably should have decayed by now.
In general no, no on so many levels wormholes, not stable; microscopic black holes, not stable and would have decayed by now. White holes don’t happen so we’re kind of left with no.
Fraser: But if you were going to try to send information, could you send information through a wormhole?
Fraser: Even that would collapse a wormhole? Even just like sending photons, you know radio waves through it would collapse it?
Pamela: Just the existence of it collapses it. They’re not stable in the geometry we have for space and time.
Fraser: Although they are kind of theoretically predicted it is sort of the same thing as white holes, right? They would just collapse as you say instantaneously if you actually were able to create one.
I’ve read varying research and seen articles about it that a wormhole would take the better part of the energy of the universe to try and open up and then as you said collapse instantaneously wasting the better part of the energy of the universe.
Pamela: Not something to be encouraged so close to Earth Day.
Fraser: So no possibility. Let’s move on. Oliver Clap from Australia says: you mentioned that we know that the universe is expanding by a specific speed and that we can determine a direction of movement, but do we know where the center of the universe is or where the origin of the big bang is? Can’t we just look in the opposite direction of the expanding galaxies and determine an approximate center of the universe?
We did a whole show on this which is I believe ‘Where is the Center of the Universe”, but we can kind of give a quick version. Is there a center of the universe?
Fraser: No so if I look off to my left and see galaxies expanding away from me and then I look off to the right and see galaxies expanding away from me, doesn’t mean that I’m at the center of the universe?
Fraser: Right, and why not? [Laughter]
Pamela: You said you wanted the quick answer. Just sort of like imagine and this is an analogy I keep going back to that all the galaxies are the raisins in a rising thing of raising bread dough. We’re just the microbes on the raisin.
As the dough expands you can be anywhere inside the blob of dough and you will see all the raisins moving away from you as the dough between the raisins gets bigger and bigger.
If you were able to somehow reverse this yeasty process all of the raisins would feel themselves getting closer and closer to one another as the stuff between them gets smaller.
It doesn’t matter which raisin you’re on just like it doesn’t matter which galaxy you’re in anywhere in the universe. You always perceive everyone moving away from you and everyone moving towards you if you go backwards in time.
Fraser: To sort of do this experiment in two dimensions, keep in mind this is just two dimensions. Take a balloon blow it up a tiny little bit and then put a bunch of dots on it at equal distances and then blow up the balloon some more.
You’ll see that every dot moves away from every other dot the exact same amount. If you were on any one of those dots on the balloon looking at the other dots you would see them all moving away from you at the exact same speed.
Obviously a balloon is a 3-dimensional object and it has a center point in the middle of the air in the middle but from a 2-dimensional standpoint there is no center to the 2-dimensional surface of the balloon.
Pamela: There is no center to the 3-dimensional universe that we live in. We can’t discuss what we’re expanding into. Just like the balloon if you live on the surface of the balloon it has no knowledge of what it is expanding into. It’s just expanding and our universe is just expanding.
Fraser: We did a show called “What is the Universe Expanding Into”? You might want to check that one out as well.
Phil Courtney from Newburry UK asks: Does the size of a star affect the speed/velocity distance that a body requires to maintain a stable orbit around the star?
Pamela: Yes. It is good to say yes.
Fraser: You got to say yes! [Laughter]
Pamela: The thing about stars is to be stable at a given diameter they have to have a certain amount of mass. If I have two main sequence stars, two stars that are both burning hydrogen in their cores into heavier and heavier elements these two stars, if one has a larger diameter than the other one, the one with the larger diameter is going to have to have a larger mass as well. It is actually the mass that matters. If you have a more massive star, an object orbiting around it is going to have to go faster in its orbit at a given distance to stay there.
If we were to take the Earth, keep it where it is and replace the sun suddenly with an object that was twice as massive our Earth would go spiraling in towards the sun and it would end up on an elliptical orbit plunging closer to the sun than it currently gets. If we wanted to stay where we are now we’d have to increase our velocity.
Fraser: Yeah but Phil’s question is about the size of the star. So if we replaced our sun with a black hole of the same mass would that affect the orbit of the Earth?
Fraser: So your answer was no?
Pamela: Well but I wanted to say yes so I used diameter to give it mass.
Fraser: Alright, isn’t there some point like say with the Roche limit of the star? If you had a star that had the same mass as the sun but was almost out to the orbit of the Earth would the Earth orbit in the exact same way?
Pamela: There would be more frictional forces, more tidal forces if we’re just about grazing because we’d have our atmosphere and its atmosphere touching and all sorts of touching slowing things down. That would start to have an effect.
That’s not just the gravity that is making it stable. This is where you’re starting to basically yank the things due to friction. That’s a different kind of affect. If you’re looking strictly at does the orbital mechanics equation balance out the diameter won’t matter.
Fraser: Right so the diameter of the star doesn’t matter for what orbit the planet or some object has to go around a star. It’s all the mass, only the mass of the star is what matters.
Fraser: Timo Marcannon from Victoria, B.C. asks – that’s on my island! When a galaxy or group of galaxies are found in the far reaches of the universe can scientists figure out what is physically occupying that space today? Can we not see it because the light was sent billions of years ago and they’ve been destroyed or galaxies have merged together?
So can we when we look at objects that are billions of light years away we’re seeing them as they were billions of years ago, so can astronomers know what’s there today even though what we’re seeing has been long gone for billions of years?
Pamela: This is such an amazingly complicated question. There are two different problems. The first is defining occupying that physical space because the universe is expanding.
So are you asking me what is occupying the co-moving volume of space that is expanding away from us and has been carried away from us by the expansion of the universe, or are you asking me what is filling the space that is the same distance from me today that that object was when it emitted the light?
Fraser: Okay, I can imagine an analogy. I take a photograph of one let’s say of a spot on an escalator and then I come up to you and say can you tell me what’s in this spot on the escalator right now?
I guess you’d kind of have two questions: do I want to know what’s on that stair right now or do I want to know at that exact same spot of the escalator? Although it is going to be different stairs there now, right?
Pamela: That’s exactly the problem.
Fraser: I guess those are the two questions then. Let’s go with both, why not answer both?
Pamela: If you’re asking me what’s on that stair that’s getting carried away I can say well that group of galaxies has probably been carried off toward the nearest cluster of galaxies.
But if it happened to have been the largest thing in its neighborhood it might have just stayed put where it is. The galaxies inside of it have merged, evolved, have changed.
If it is the biggest thing in its neighborhood it has probably consumed some of its nearby neighbors. We know how space in general is evolving. The diffuse background of galaxies in the far past where we had small clusters, we had in many cases even small galaxies originally. Things have been merging and building and the voids have been getting bigger as the clusters themselves have been getting denser.
It is where the small things went that gets to be more difficult because then you have to start figuring out what was all of the stuff that might have been yanking on this small thing.
As for what is in that particular place on the escalator if instead of asking about that stair that is carrying the cluster of galaxies further away.
If instead you want to know what is in that particular place relative to the landscape, I can’t answer that one.
Fraser: Because the expansion of spaces continue to go on and you don’t really know what’s there now.
Fraser: Liz Frasek from Pawhuska, Oklahoma asks: how does one become an astronaut?
Pamela: Very, very carefully.
Fraser: Yeah, that’s a whole show on its own. Maybe we should do that as a show. [Laughter]
Pamela: I have to admit that this is one of those things that when you start looking at all the different characteristics of all the different astronauts, they come from such a diversity of backgrounds that there is no one clear recipe.
There are certain factors that turn up over and over again. Military experience, being Eagle Scouts for the men, having the ability to do some combination of medicine, and speak foreign languages and being technologically literate. All of these things all at once go into many of the different people who are selected.
Fraser: Right there are a couple of classifications. There are the people who fly the spacecraft the pilot, the commander. Those people generally come from a military test pilot background. They’ve been in the Air Force, Navy, they have flown aircraft.
They are at the top of their game. Plus they have one or many advanced degrees although you know not necessarily in physics, engineering, medicine and things like that.
Pamela: There are medical doctors.
Fraser: Then they have what are called mission specialists. Mission specialists don’t need to have been a test pilot but then you’ve got to be an amazing human being.
This is where you’ve got multiple PhDs as you said a tremendous amount of real world experience in medicine, science, and physics.
It is amazing to see because so many people want to be astronauts and NASA and ESA can choose from just like the greatest people in their respective countries.
Pamela: You have time to get there. That’s the really amazing thing.
Fraser: Sure but if you’re young and you want to be an astronaut
Pamela: Be amazing today. You have to be amazing for a long time.
Fraser: Yeah, get rolling and you have to put in the same level of commitment to it as to be in the Olympics.
Pamela: Right you have to be physically fit, you have to be intellectually fit. You have to be diverse. You should learn Russian.
Nowadays you probably should also learn Chinese and look to see where you think the next great space faring nation is going to come from. You have time.
The people that they hire to be astronauts are often in their mid-thirties and early forties. To get there especially as a mission specialist you have time.
This is one of those rare exceptions of you really can’t start early enough in terms of both the physical fitness, going to the big schools, going to the good graduate schools, getting the right jobs and just staying after the dream every single day.
Fraser: Or, pay twenty million dollars.
Pamela: That works too.
Fraser: So, one way or the other. I actually think that’s the easier way. [Laughter]
Fraser: Really, go into business, save up twenty million dollars and buy your way onto the International Space station on a Soyuz flight.
I think that’s the less complicated one that you have more control over. That’s plan B.
Pamela: I bet that there are probably more people on the planet Earth who have those twenty million dollars than are in all the astronaut cores of the world and have gone into space.
Fraser: Now you know what you’re up against. This is John Holmes from Ankara, Turkey: how is it that scientists accurately account for Earth plate tectonics and other movements of our Earth-based instruments and facilities?
So, this is kind of relating to the kinds of things like we talked about how there is the reflectors on the moon and we can detect that the moon is moving by a couple of centimeters a year, drifting away from us.
We also know that for example thanks to plate tectonics here on Earth the plates are shifting apart a couple of centimeters and so you’re moving further away from the moon just on the surface of the Earth wherever you have your laser. How do scientists keep those two things in mind and in balance?
Pamela: GPS. Here’s the thing. We can’t really measure very accurately where we are on the surface of the Earth from the surface of the Earth. The Earth’s crust flexes in response to the moon just as much as the oceans.
We have to be able to take especially with people that are measuring pulsars for instance where they need to get extremely accurate timings; we have to take into account the tides of the Earth.
We have to take into account the flexes of the planet. To do this we have to start making our measurements off of satellites that are orbiting the center of mass of the planet.
It is by measuring how these timings change, by measuring how the orbits of the satellites change that we’re able to very carefully first map the gravity of the planet and also map the motions of the surface of the planet.
Fraser: They do it by taking it all into account. They have to and so they know they’ve measured with GPS how much for example a facility rises and falls with the tides every day even though it is on the ground.
They do take into account I guess plate tectonics and the distance of the moon and all that. They’re very careful.
Pamela: We can calibrate things using pulsars. This is one of the really cool things is the most precise timing mechanism that we know of is pulsars.
By looking at how the arrival time of the pulsars changes we can make sure that we got all the rest of our answers right.
Fraser: That’s crazy. That’s amazing.
Pamela: It’s cool though. [Laughter]
Fraser: Not crazy I mean dedicated and focused and very careful. Jason Parsley from Lakeland, Florida: what would happen if the moon were to fracture into a bunch of tiny pieces like a puzzle and become a giant floating rubble pile? Would that change the affect of gravity on the Earth?
It’s not really possible but imagine someone exploded the moon from inside but not in such a way that it completely blew apart. It just kind of reformed itself into a pile of rubble. Would that change the tides or anything on the Earth?
Pamela: No as long as the moon is in the same place and the chunks are gravitationally chunked together even if the molecular bonds and the minerals and everything else is broken into a zillion little pieces.
As long as the center of mass stays the same distance from the Earth’s center everything is going to be happy. Everything is going to keep moving along.
The issue you now have is this body that isn’t held together any longer. The chunks of moon that are closer to the Earth are going to want to orbit at one rate.
The chunks of moon that are at a more distant place are going to want to orbit at a different rate. Over time this blob of moon unless it gravitationally holds itself together, it just depends on how much energy you give these chunks.
If you give the chunks enough energy that they can escape the gravitational well of this now basically rubble pile, you might end up with something that is more ring-like than moon-like.
As long as those blobs can gravitationally hold themselves together everything is fine. It is going to behave just like the moon; it is just going to be more interesting to look at.
Fraser: Back to the original question that we asked, if we replace a rubble pile with a black hole with the mass of the moon no difference, still get the tides, everything. It just comes down to the mass.
Pamela: No difference.
Fraser: What if you were to stand on the rubble pile? Would it feel any different?
Pamela: No not really because as long as the rubble is held together gravitationally you’re still going to have the same pull from the center of mass of that rubble pile that you have normally from the moon.
You might have a slightly crunchier surface but the regulus itself is pretty crunchy. I think you’re just basically looking at the same sort of experience but much more artistic in its rendering.
Fraser: In a few billion years the rubble pile would all merge into a nice perfect sphere again.
Pamela: Yeah, that’s the nice thing about gravity.
Fraser: You wouldn’t even know that it had ever happened. David Shaun Siever from Montana asks: if the universe is expanding faster than the speed of light and in the future we’ll see less and less of the universe that we can see now why couldn’t it be that the age of the universe older than we think and there’s matter that is beyond what we can see now?
I guess what David is asking as we mentioned in previous shows although nothing can move faster than the speed of light the objects that are being carried away by the expansion of the universe as it is accelerating can eventually be receding from us faster than the speed of light.
At that point they will stretch out into the red and look like these sorts of ghostly artifacts on the edge of the horizon and then eventually disappear. Could it be that that has already happened and that we just can’t see a much larger universe and then that might mean that the big bang didn’t happen how we thought and that there is more universe out there?
Fraser: Nope, okay, moving on. [Laughter]
Pamela: Seriously though the cosmic microwave background is there as a check on all of our math.
Pamela: Because we’re able to look out and say ah, cosmic microwave background and then we’re able to say ah, early in the universe we have nice much less chunky distribution of stuff. As we look at clusters that are closer and closer to us we see that they’re more and more clustered.
We can actually see the universe going from not smooth but smoother distribution of galaxies and galaxy clusters to this fine filigree with large voids in-between the structures.
By being able to see the entire picture from the cosmic microwave backgrounds of today we have all these different places that we can check that we understand what’s going on. We can check that yes all of this matches with the universe that’s 13.7 plus or minus .2 billion years old.
Fraser: That isn’t always going to be the case is it? A few trillion years down the road David’s comment is entirely true. Astronomers will be sitting there talking and be like we don’t know how old the universe is.
Pamela: This is one of the things where astronomers hate to say that we live in a special time or a special place. It does appear that we do live in a time that is one of the rare moments given the entire duration of how long the universe is going to last.
We’re lucky enough to live in one of those moments where we can see enough of the history of the universe to understand the history of the universe.
Fraser: There will be a time, trillions of years in the future when the cosmic microwave background radiation will be so red-shifted that we won’t even be able to see it.
Some of the more distant galaxy clusters will be accelerating away from us at faster than the speed of light and we won’t be able to see their light anymore. We’ll have no idea how old the universe is anymore. That’s kind of sad.
We’ve got a whole show on this. We have a 2-part show called “The End of Everything” where in the first part we talk about the end of the solar system all the way up to the end of the solar system. In the second part we talk about the end of the universe and cover this as well. That’s in there.
Mike Robinson from Ontario, Canada asks: you’ve mentioned before that two ground-based observatories can use a technique called interferometry to increase the effective resolution of the combined images. Couldn’t this be used in space telescopes?
Could you make a space telescope where you put observatories on either side of the sun and make a telescope with a resolution of the Earth’s orbit? Are any space-based interferometers in the works?
Pamela: Sort of, kind of I don’t get to say yes or no on this one.
Fraser: Terrestrial Planet Finder.
Pamela: That’s where the sort of kind of comes from. Terrestrial Planet Finder is one of our favorite missions. It is the one that just shows no signs of making it to the launch pad. It is a cool mission.
It actually is three different space telescopes working together as interferometers communicating with a central hub. They’re not exactly spread out on either side of the sun but they’re spread out enough that you can do things that we just can’t do from here on the surface of the Earth.
Fraser: Oh, like detect life on other planets maybe?
Pamela: Right all those cool sorts of things.
Fraser: You know that little thing. [Laughter]
Pamela: Building one of these that sticks things on either side of the sun gets a little bit more complicated because they can’t talk back and forth because the sun is in-between the two of them.
If you got creative and you figured out how to do this with three things, one in front of the sun and one to either side and they were communicating with the one out in front it still doesn’t work quite so well because you want to be able to combine the lights. You want all the light paths to be equal so you can’t quite do that.
You end up having to figure out well then yeah there is no easy geometry that involves orbiting the sun. You can get the groups of them with rockets to keep them together so you have to constantly be correcting the orbits. You can find ways to get them orbiting around the sun spread out enough that you can do really cool things.
Fraser: I guess it is a failure of our current technology and the ability of the precision of our technology but it is theoretically possible to locate three spacecraft in orbit around the sun and create interferometer. If you could somehow sync up these signals you could indeed have a telescope the size of the Earth’s orbit.
Fraser: Whoa. Now that would be all about resolution, resolving power, right? It would allow you to see how far apart the buildings are on planets orbiting other stars. [Laughter]
Pamela: I don’t think it would be quite that good of resolution but yeah.
Fraser: How far apart the trees or the branches of the yeah.
Pamela: It would be maybe able to let you see if Jupiter has a really cool giant moon. That’s still pretty cool.
Fraser: That would be pretty cool. Last question comes from Dagua from Ghana: I viewed Saturn through a telescope and quickly saw that the rings are hardly visible. Research has shown that Saturn is going to be in this position for quite some time. I was wondering why is Saturn edge on? The rings were nice and visible years ago what made the planet turn edge on? Do the planets roll in their orbits even though they’re also rotating on their axis?
So, is that true? If you looked at Saturn right now in the middle of 2009 would you be able to see the rings of Saturn?
Pamela: Only sort of kind of because he’s right, they’re going edge on right now. In fact this is leading to some really cool images where we’re seeing some really amazing shadowing across the surface of the rings from the Cassini mission.
In general the planet Saturn goes through the cycle where we go from essentially looking so that we can see the north pole of Saturn and see its rings fairly face on to it rotates from summer in the northern hemisphere to seeing the rings exactly edge on. This is more like the equinox for Saturn. Then we start to see the south pole of Saturn.
Fraser: Right and the process that’s going on here is exactly the same as why we have the seasons here on Earth.
Pamela: It just takes a lot longer because Saturn is further out. We’re just seeing it relative to the stars it keeps the same pole pointed towards the same star all the time.
As that entire system orbits around the sun what’s pointed at the sun changes from Earth year to Earth year as Saturn progresses year by year around the sun.
Fraser: Saturn is not rolling or tumbling or in any way changing its orbit. In fact it is being perfectly stable. It is like a top that is spinning.
It’s just that from our perspective we’re seeing various angles of Saturn. If you were to stand on Saturn the same star would be right over your north pole all the time the same way that we have it here on Earth.
Pamela: You can simulate this with a school globe. If you take a globe that is mounted so that it is tilted and put basically a fin all the way around it so it is like the Earth globe has its own ring going around its equator.
If you then hold it so that it is always keeping the north pole pointed at one wall and bring it around your head you’ll see it so that that disc that you’ve artificially put around the planet Earth goes from edge on to face on to edge on to face on again as it goes around and around.
Fraser: Right and I was going to come up with some analogy where you’d have some friend hold their arms out orbit you. [Laughter] Have a hula hoop but that’s it.
Pamela: Yeah, just use your school globe. [Laughter]
Fraser: Use your school globe and that’s the point is that you make sure that the north pole of the globe is always facing in exactly the same direction. Don’t turn the north pole and south pole as you move it around you always keep it in one direction.
You’ll see how for one part of if you’re looking at the bottom of the globe and you’re seeing the rings full on. Then a little after that you’re seeing the side of the globe and the rings are edge on.
Then you’re seeing the top of the globe and you’re seeing the full rings again and then you’re seeing the edge of the globe again and so you’re seeing the other side of the globe and the rings are edge on. That’s all that’s going on.
Pamela: And that’s pretty cool.
Fraser: Alright but if you haven’t seen Saturn in a telescope yet another wake up call you know get out there. I don’t care how, beg, borrow, steal some telescope time with a friend and stick your eye to the eyepiece and see Saturn with your own eyeballs and your own brain for once in your life.
You’re listening to AstronomyCast almost 200 episodes if you include all the questions [Laughter] you haven’t seen Saturn in a telescope with your own eyes? I’ll just have to keep nagging. Do it! [Laughter] It is the greatest thing ever. It completely changes your opinion of astronomy and brings it all home.
Pamela: While this isn’t the best year to do it, the Galileo scopes that are getting sold by IYA which are only about $15.00 are good enough to see Saturn’s rings even as edge on and sad as they are.
Fraser: I looked through one. I saw the moons of Jupiter and bands on the planet of Jupiter. These Galileo scopes are perfectly acceptable. For $15.00 you can get your own telescope. Get on it! Thanks a lot for the questions Pamela and we’ll talk to you next time.