Title: Andromeda Has Never Been So Hot
Written By: Aaron
Castdate: 051116

Travis	Welcome to another edition of Slacker Astrology...(pause) dang it! I messed up again.
Pamela	I'm sorry folks, the voodoo astrologers have been getting revenge on Travis for our Slacker Astrology skit a few weeks ago.
Travis	I think I'm better now. Let's try it again... Welcome to another edition of Slacker Astronomy. Each week we bring you a recent news event in the world of astronomy. * And if there is nothing new, we'll imagine that we're in a tropical paradise, on the beach, sipping mai tai's and thinking of nothing - absolutely nothing at all...
 * - start playing soft, relaxing carribean music in the background. if you don't have any let me know and I'll give you a clip. Maybe "Lazy Lover" by Brazilian Girls at around 1:30-1:40? Then read this slowly, as in bliss...
Pamela	Wait, Aaron is doing that right now from a beach in the Philippines. Perhaps he is responsible for this wicked voodoo? While we slave to keep SA on the air, he is off vacationing. He definitely puts the slacker in slacker astronomy.
Travis	Well he did leave us with some cool news about one our nearest galactic neighbors, the Andromeda galaxy.
Pamela 	Also known as M31, which is its Messier number. Amateur astronomers like to show off to each other by calling deep sky objects by their Messier numbers instead of their regular names. So remember Andromeda as M31 and you'll pass the secret handshake test at your next star party.
Travis Astronomy is an amazing science. And galaxies are among the most amazing objects in astronomy. They are massive islands of material moving through the vastness of space. Every astronomical source we can see is either inside a galaxy, or a galaxy itself.
Pamela Sure, there are stars and planets floating through space outside of galaxies. When galaxies collide they throw stuff out all over the place like drunken frat boys at a fourth of july bar be cue. But they are way too small to be seen from Earth against the vastness of space.
Travis	So we can see two types of objects from Earth: things in our galaxy, and things in other galaxies.
Pamela	The closest known galaxies to Earth are the Sagitarius galaxy and the Large and Small Megallanic Clouds. But they are all tiny dwarf galaxies in the process of merging with our own.
Travis	When we think of galaxies, we usually think of large white discs with spiral arms. Pictures that look like Andromeda, which is the closest *real* galaxy to Earth.
Pamela	It is about 3 million light years away, or about the distance between exit ramps on a West Texas highway.
Travis	You'd think something that far would be difficult to see. But it isn't. Andromeda can actually be seen by the naked eye. If you are under pristine and dark skies, it will look like a tiny grey cloud in the constellation Andromeda.
Pamela	Oh I get it, it's named after the constellation it is in.
Travis	Astronomers are not known to be especially creative folk.
Pamela	As proven by this podcast.
Travis	Sad - but true!
Pamela	It does help us find it, though. It is easy to get lost in the night sky.
Travis	The cloud will usually appear about the size of a full Moon. But it could appear larger if your eyes are very good and the skies very dark.
Pamela	Take a pair of binoculars to it. It should be easy to find in binoculars of any size. You will be able to easily make out its oval shape, which will look slightly tilted.
Travis	You can do that from the city because don't need dark skies with binoculars. With a telescope and dark skies, you can even see some structure!
Pamela	Just remember to resist the urge to peek into the neighbor's window. That will destroy your night vision.
Travis	Not to mention relations with your neighbors.
Pamela	Andromeda is a lot like our own Milky Way galaxy. It is even similar in size, with some astronomers saying it is bigger and some saying it is smaller. Right now it seems that it may have a larger radius than the Milky Way, but that our galaxy has more mass.
Travis	So when we study Andromeda, we're learning a lot about our neck of the woods as well.  And just like our own galaxy, which is swallowing up smaller ones nearby, Andromeda is also feasting on some of its own smaller satellite galaxies.
Pamela	Recent images by the Spitzer Space Telescope reveal the leftovers of past feasts. Spitzer is an infrared telescope orbiting the Sun far from Earth. It is the state of the art in infrared observatories and has been able to unveil new images of Andromeda at incredible resolution.
Travis	The new detail reveals a hole in the disc, leftover from when a satellite galaxy passed through it. We can also see that satellite galaxy with backyard telescopes, and it has its own name: M32 and looks like a small grey fuzzball just off to a side corner of Andromeda.
Pamela	As M32 passed through the disc, it created waves that are rippling outward. These waves spur intense star formation. Young stars tend to be warmer than older stars, so as a whole they appear bluer.
Travis	As a result, star formation rings in a galaxy tend to look blue and white. We see these blue and white rings in Andromeda, and now with the Spitzer evidence, we can tie some of those rings to M32's recent collision.
Pamela	So M32 slammed through the disc, sending out density waves that beget star formation. Then it passed through the disc, losing momentum in the process.
Travis	Now it will slow down and then make another pass through the disc in the future. This time it won't go as far because it is slower. And, like a pendulum spinning down, it will go back and forth through the disc until it settles down and becomes part of Andromeda.
Pamela	In the infrared, Spitzer is looking at heated dust in the galaxy. Much of this dust is relatively cool compared to the white hot star formation rings. Spitzer is able to see older, cooler stars and dust that was left behind by M32 and other past collisions. By combining this information with our optical and ultraviolet images of Andromeda, astronomers are able to connect the dots and associated cause and effect.
Travis	For you couch potatoes out there, you can think of Spitzer as having found the smoking gun that solved the case.
Pamela	Does that mean we have to end this episode standing around in an office waxing cynically about crime and punishment, holding self important poses for the camera?
Travis	No way, we still have some more science to cover.
Pamela	Hallelujah for podcasts!
Travis	And no commercial interruptions!
Pamela	True, but what if you need a bathroom break?
Travis	You just take the podcast with you!
Pamela	Ooooh, I prefer not to think of us in 11 thousand bathrooms.
Travis	Speaking of toilet TV, let's get back to Andromeda.
Pamela	Kevin Sorbo is going to kill you.
Travis	Well then I know Gene Roddenberry will thank me in Heaven.
Pamela	We have a confession to make. The reason we're doing this episode is not related to science at all.  It has to do with a pretty picture.
Travis	(cocky) Admiring my headshot again?
Pamela	No, this has to do with Andromeda.
Travis	Oh, admiring the hot computer hologram actress?
Pamela	No, back to the galaxy Andromeda- not the TV show.
Travis	BOOOOORRRRIIINNNGG....
Pamela	Not when you see this. Spitzer's image of Andromeda is amazing. It looks like a galaxy on fire.
Travis	It took more than a day of imaging for Spitzer to take this picture. Andromeda is so close and so large that it is bigger than Spitzer's field of view. So it had to take many pictures of different pieces of the galaxy and then astronomers assembled them into a mosaic.
Pamela	Humans cannot see infrared light. So for infrared pictures scientists take the infrared data and transform it into a color human's *can* see. This is called false color mapping and is done by all astronomers working in wavelengths other than optical.
Travis	The Spitzer folks have used a palette of orange and reds for this image. Combined with the level of detail we see and the size of the object, this makes for a very dynamic and beautiful image.
Pamela	And they are not cheating! For infrared images, it is considered standard to use those colors because reds are at the long end of the optical wavelength.
Travis	On the flip side, blues are at the short end. So for shorter wavelength images, like in the ultraviolet, astronomers will use blue and white colors instead of red and orange.
Pamela	This is beautiful picture is not merely eye candy colored up by a publicist. Sure, the PR folks came up with neat captions and cropped it well. But this is legit science presented in a legit way. It's just way cool.
Travis	Although it is funny how we associate a fiery palette like red/orange with cooler wavelengths.
Pamela	Contrariwise, the icy blues and whites are associated with hot wavelengths.
Travis	Such decisions would never pass a television studio's art department.
Pamela	This is true, all you have to do is see some of the bizarre visuals they come up with in astronomy shows on the Discovery Channel. This weekend I saw them do an animation of what would happen to a human if they stood on the surface of the Earth *as it was being created*!
Travis	That is indeed quite a stretch.
Pamela	If anyone can tell me why someone needs to see that, let us know by posting a comment in the Show Notes on our site at slackerastronomy.org.
Travis	Also in the Show Notes we have that magnificent photo from Spitzer. Check it out!
Pamela	We also have a link to the new Spitzer Space Telescope podcast. They interview a couple of the scientists who helped create this picture. We highly recommend the podcast.
Travis	Thanks for listening to another episode of Slacker Astronomy. Send feedback to info@slackerastronomy.org.
Pamela	And don't forget to donate to our Katrina Astronomy Fund by clicking on the link on our home page.
Travis	For our author Aaron and Pamela, I'm Travis. Thanks for listening.
Pamela	You've been listening to slacker astronomy, a podcast for you, for fun, for the voices in our heads.