Enjoy your weekend!

And I’m going to do it naturally, by telling the story as the Universe tells it directly to us. I call this project Genesis. Check out the teaser trailer below, and tell your friends, because this is coming in January.

Alternatively, you can see it in 4 separate youtube parts (below):

Well, playing drums and piano kinda. But damn, I would love to have those editing skills…

But what would we see, here in the Milky Way, as Andromeda got closer and closer to us? Right now, Andromeda looks like this:

But Andromeda is also very far away: about 2.3 million light years (770 kpc). The center of it is tiny on the sky, but the whole galaxy, as seen above, is actually 4 degrees across, or eight times larger than the diameter of the full moon! Its apparent magnitude is 4.4, which means it can barely be seen with the naked eye (anything less than 6 can be seen with your eye) if your vision is good and there’s no light pollution.

But the Universe will continue to age, and gravity will basically tell Andromeda “Get over here!” When this happens, Andromeda not only gets closer to us, but also starts to appear bigger and brighter in the sky. What does this mean? Let’s play Zeno’s Paradox, and see what happens when it gets halfway to us, and then halfway of that distance, etc.

• About 1.9 billion years from now, Andromeda will be 385 kpc away from us. It now has an apparent magnitude of 2.9, which means it’s just barely visible from most urban neighborhoods, and appears slightly brighter than our own Milky Way does. It now takes up 8 degrees on the sky, making it 16 times as large as the Moon in diameter.
• About 2.7 billion years from now, it will be within 190 kpc of us. That’s still well outside the Milky Way, which is less than 20 kpc in radius. It’s now quite bright, though, with an apparent magnitude of 1.4, making it as bright as one of the brightest stars in the sky, Regulus. It is now 16 degrees on the sky. If, at this point, it were oriented face-on to us, it would take up about 1% of the entire visible night sky.
• About 3.2 billion years from now, it will be under 100 kpc from us. It now takes up 1/20 of the entire night sky, and only the Moon, the Planets, and three stars, Sirius, Canopus, and Alpha Centauri are brighter than Andromeda appears.
• 3.4 billion years from now, Andromeda will be within 50 kpc of us, on the verge of beginning to merge with us. (Remember, it has a radius of about 20 kpc, too.) Its apparent magnitude is -1.5, meaning that it is now brighter than any star in the sky. It will now take up about one-fifth of the night sky, and will just begin to create new star-forming regions in the outskirts of the galaxies, where the gas begins to merge.

And then the merger happens. What will that do to us? Take a look:

Although we don’t know exactly what’s going to happen, it’s a good bet that we won’t want to be here for it. Time to find a new galaxy… or at least a temporary home outside of ours while that merger takes place!

Then we got clouded out, and right now, during totality, the entire sky is covered in clouds. But I started thinking, “What if I were in space?” Well, the Moon appears red/orange every day during Moonrise/Moonset from Earth, but would appear white from space. But the red/orange during a total eclipse? The Moon would still be that color even from space during an eclipse! Even to a Venusian or a Martian! In fact, to someone anywhere in space, a total lunar eclipse would be the only time the Moon would appear reddish/orange.

That’s all; a quick post because I thought that was neat. Hope your eclipse-watching goes better than mine!

UPDATE: Orbiting frog has a few things to say about that, but one thing they have is a (computer generated) video of what watching the lunar eclipse might be like from the surface of the Moon! Take a look below:

And if you haven’t gotten enough Astronomy yet, take a look at this week’s Carnival of Space, where they link to my awesome post about why we need dark matter!

Thank you for your recent email application for Dangerman.

If you are still interested in being considered for this role we’d like you to make a short video of yourself (no longer than 3 minutes). Tell us, on camera, why you would be the perfect Dangerman (or Woman) and explain the science behind a dangerous stunt in an entertaining way which would make sense to a non science-educated viewer.

If you already have footage of you performing the stunt you are explaining or another similar one, you could supply that too, but it’s not essential and no particular preference will be given to applicants who supply ‘stunt’ footage.

After debating exactly what they wanted, I decided that they were most looking for a short video of just me, speaking to the camera, to assess whether I was what they wanted or not. Here is my audition for Dangerman.

Here is a video of someone actually dipping their hand into lead, and you’ll notice he makes sure to wet his hand first! This would really be a dream job if I could get it; wish me luck! In fact, I’m not sure whether it would help or not, but if you wanted to email Anthony and tell him you saw my youtube video and would love to watch Dangerman hosted by me, it couldn’t hurt. I’ve already talked to Jamie about it and she would be happy to come with me to London; let’s hope it happens, since this really would be a dream job for me!

Did you see that?? It’s a fish that hunts insects by shooting them with water, and then eating them when they fall into the water, often catching them before they ever leave the air! What’s really amazing about this is that the fish needs to be able to “shoot fish in a barrel” in reverse.

Shooting anything either from air into water or from water into air is actually really difficult, because light refracts, or bends, when it changes from traveling through one medium to another. The reason it happens is because light travels at different speeds in water than in air (see the hypnotic animation at right), and the scientific law for how it happens is called Snell’s Law.

Does that mean these Archer Fish are programmed knowing how to do this in their heads? No, of course not! Young Archer Fish travel in schools, shooting randomly upwards at insects, and the ones that are the best shots, the fastest feeders, and the most successful at avoiding predators are the ones that survive to adulthood, and those are the ones that can hunt like in the video! Of course, at this fish farm in Malaysia, they teach Archer Fish to hunt in packs even to adulthood, they could be the world’s smartest fish!

What is a galaxy, anyway? Why does it look like a big bright fuzzy star? And why are there different types of galaxies; shouldn’t they all be the same?

This might come as a surprise, but 100 years ago, it was pretty much accepted that we were the only galaxy in the Universe. In fact, there was a great debate in 1920 on whether some funny-looking things in the sky were other galaxies, or whether we were the only one.

So here’s the deal. You look up at the sky, and all those points of light you see are either planets (left) or stars (right).

But with a telescope, you find that there are some fuzzy things in the sky that don’t quite look like you’d expect them to. There are star clusters, like the Pleiades. And there are the bizarre looking objects known as nebulae. There were planetary nebulae, like the Crab Nebula (M1), but there were also things known as spiral nebulae, like Andromeda (M31), to the left.

Sure, we know today that Andromeda is a galaxy and the Crab Nebula is the remnant of an exploded star, but how do we know that? The Milky Way is our collection of about 400,000,000,000 stars. Some of those stars are known as Cepheids, rare stars that flare brightly at predictable intervals. By 1925, Edwin Hubble had found 10 Cepheid stars in Andromeda, and measured their periods and brightnesses over long times, figuring out that Andromeda was both very large and far enough away that it was outside our own galaxy.

It didn’t take long for people to figure out that Andromeda also had a few hundred billion stars in it, and that not only were all the other “spiral nebula” actually spiral galaxies, like the Whirlpool Galaxy (M51) shown here:

but that galaxies, these huge collections of millions or even billions of stars, existed with a really wide variety of shapes and sizes. In addition to spiral galaxies, there are also elliptical galaxies, like the galaxy Centaurus A shown below:

So we’ve got spiral galaxies and elliptical galaxies as the two major types of galaxies in the Universe. Spirals are shaped like a disk, usually with a bulge and sometimes with a bar in the center, with big, bright arms spiraling outwards from the center. On the other hand, ellipticals are shaped like an American Football, with a big bright center becoming dimmer and more diffuse towards the edges. Let’s show you how you form a galaxy, and then why some of them wind up as spirals, while others become ellipticals.

When the Universe is very young, it’s also very smooth, but there are regions of space that contain more matter, both dark matter and normal matter, than average. There are also some that contain less matter, and the famous picture at the right shows you the average places in green, the below-average places in yellow/red, and the above-average places in blue. Each individual overdense (blue) place, where there’s more matter, is going to collapse under its own gravity.

If the overdensity were a perfect sphere, everything would collapse to a point at the center. But one direction, randomly, will always be shorter. Because it has less distance to go, that direction collapses first, and we go from an ellipsoid:

to a “pancake,” or a disk, because gravity squashes it in the shortest direction. When all that matter meets up, the dark matter just passes right through, but all the normal matter (protons, neutrons, electrons) can’t just pass through each other, just like your hands can’t pass through one another. So they stick together, and start forming stars, producing a whole bunch of light in this disk:

The disk then rotates, by the law of conservation of angular momentum, and the rotation makes the spiral structure we see, since the inner part rotates with a higher angular velocity than the outer part. So, what we wind up with is a spiral galaxy surrounded by an ellipsoidal halo of dark matter:

And that’s how we get spiral galaxies! Wait a minute, then, so how do we get elliptical galaxies, and why are there so many of them in clusters, but when we see galaxies on their own, they’re almost all spirals? We think that all galaxies start as spirals, but some of them merge together. When you get a small galaxy merging with a big one, the small one gets destroyed and the large one is mostly unaffected, like the large Magellanic Cloud falling into the Milky Way. But when you get two large galaxies merging together, they destroy the spiral structure and make an even bigger elliptical galaxy, as this video shows what might happen to our Milky Way were we to merge with Andromeda:

So, to recap, galaxies are collections of millions, billions, or trillions of stars that can either form in isolation, like spiral galaxies, or can form as the result of multiple galaxies merging together, like ellipticals. Now yes, there are other types of galaxies, like irregular galaxies or the very rare ring galaxies. These are both thought to be the result of a complicated gravitational interaction or merger, and many irregulars may well wind up looking like ellipticals a few billion years from now. It’s pretty neat that the Universe is so large and so diverse that we can see, and yet explain and understand so many of the different things it does!

Thankfully, there is a person calling him/herself cdk007 making youtube videos like this one to explain how evolution works, and why arguments against it are invalid, with dauntingly demonstrative examples:

The explanation basically boils down to, regardless of how life started, once you have even the simplest life in place that reproduces, mutates, and is subject to natural selection, you will get evolution. While reproduction and mutation are random (with far more variation occurring in sexual reproduction over asexual reproduction), natural selection is not random. The fact that certain traits are selected causes events that would be exceedingly improbable at random to occur all the time.

This video is excellent, and there are many others (the Bad Astronomer likes this one); I recommend them to anyone who is looking for simple, compelling examples of how this complicated biological process works. In fact, the only explanations that I’ve ever found easier to understand were watching Episode II of Carl Sagan’s Cosmos series and watching the off-Broadway play Trumpery, a fascinating play about the scientific and personal struggles of Charles Darwin (and I think Michael Cristofer deserves to be showered with accolades for his performance as Darwin).