Don’t you love it when astronomers get excited? I mean, about the universe? (What did you think I meant?) Astronomers using the orbiting Chandra X-Ray telescope have discovered proof of dark matter, the substance that makes up 96% of the universe.

This discovery has cosmologists doing their dark matter happy dance (in your face planetary scientists!) because they just finished staring at the galaxy cluster 1E0657-56 for over 100 hours and found something totally cool. And dark. And heavy. And it’s everywhere.

As with most important scientific discoveries, this result came while trying to do something else entirely.

Astronomers were staring at this galaxy cluster as part of NASA’s ‘Name This Galactic Cluster’ Contest. NASA administrator Michael Griffin was getting sick and tired of trying to remember all of these ‘damn numbers’ as he put it.

He figured that since he controlled all the money at NASA, then by golly he was going to put those cosmologists to work, make them come up with something else besides ‘galaxy cluster 1E0657-56’.

“I mean really, are you kidding me?”, he said. “What’s up with that?”

The winner would receive a one year’s extension on their NASA grant and a month’s membership in a tanning salon (something, it turns out, cosmologists can never have too much of).

Galaxy cluster 1E0657-56 (right) is a very remarkable object. It is a collision of two clusters of galaxies (not just two galaxies colliding, but two large clusters of galaxies smashing into each other), the energy from which is the largest of anything since the Big Bang. The blue stuff in the photo above and the animation at right is where they think the dark matter is.

Imagine two medieval armies swarming towards each other colliding on a battlefield and each soldier is a galaxy. That’s galaxy cluster 1E0657-56. (Well, with one notable exception, there’s no kilt-wearing Mel Gibson, although some speculate that he is made of dark matter.)

Clearly, this contest motivated every cosmologist from Wendy Freedman to Lawrence Krauss (Lisa Randall entered the contest too but she was too busy trying to explain what the hell string theory is to everyone and why it’s relevant). Not only did they get to look at the most energetic event in the history of the universe since the Big Bang and get paid for it, but they might actually get a tan.

There were also many in the office who were sick of looking at Fred Baganoff in shorts.

So there they were, every card-carrying cosmologist, staring into their respective telescopes, many already imagining themselves in those tanning booths, when the Chandra guys noticed something weird. Actually, it was probably a grad student, working on a Saturday night. It is a known fact that science is only advanced on Saturday nights by dateless grad students.

Anyway, someone (but I’m betting it’s a grad student) added up all of the mass that they could see in this cluster and discovered that it was less than the mass of the hot gas in between the galaxies.

“WTF?”, thought the grad student. “How is it that this cluster isn’t flying apart? The hot gas in between the galaxies should cause them to fly out all over the place.”

He asked his advisor if he could please, please, please use his computer to double-check his calculations as his Apple ][+ took 30 minutes just to add two numbers together. His advisor eventually agreed but warned him not to change his ‘Dukes of Hazzard’ desktop theme.

After double and triple checking (and changing his advisor’s desktop theme to ‘Hello Kitty’, his advisor was a prick anyway), it was found that the numbers regarding the masses of the stars making up this cluster was indeed less than the hot gases in between them that were forcing them apart. What was keeping this cluster together?

After several weeks of running models on his Apple ][+ (and winning ‘Zork’, beating the Cassini guys hands down – all they had was a Vic 20), the grad student concluded that whatever was holdling these galaxies together could not be seen. It was dark.

His advisor, after a chorus of phrases like “No kidding Brainiac’ and ‘No Duh’ and ‘Way to go, Einstein’, and ‘Of course its dark, you doofus’ supplied that even though we can’t see, hear, smell, taste, touch, observe, wish, conjure, inspect, detect, invoke, materialize, remember, summon, or enchant this stuff, it must exist because the gravity of That-Which-Cannot-Be-Seen is holding the collision together.

Dark matter, as this stuff oh-so-imaginatively came to be called, is not the minutes taken at an occult membership officers meeting, rather it is the stuff that makes up over 95% of our universe. The observations of this galactic cluster collision proved it existed.

Something was supplying the gravity to hold this collision together, since the material that astronomers could see didn’t have enough gravity to do it, then there must be something else we can’t see providing the necessary force.

This reasoning is a lot like Beverly Crusher’s in that one Star Trek: Next Generation episode where the universe is gradually disappearing around her and she’s the only one left: “If there’s nothing wrong with me, then there must be something wrong with the universe.”

I jump to that conclusion at least twice a day. I live my life by it.

Whatever it is that makes up most of our universe is dark, heavy, and it’s all over the place. Be very careful where you step, it may never come off your shoe.

With this triviality out of the way, the Chandra guys submitted their entry into the galactic cluster naming contest and won. Their entry: “The Bullet Cluster”. Because the hundred million degree gas cloud shown in X-Rays looks like a bullet.

I know. I think I prefer Galaxy cluster 1E0657-56.

At least you don’t need sunglasses to look at the Chandra guys in shorts now.