When Two Galaxies Really, Really Love Each Other…

Over the past couple of months, NASA has been busy releasing a new series of stunning photographs produced by the Hubble telescope. The photos are test images that were taken in order to see how the telescope is doing after the complete makeover and repair it received in May 2009. The verdict: It’s doing AWESOME. See?

On Wednesday, I was lucky enough to be among 300 people who gathered in the Art Institute of Chicago’s (swanky) Fullerton Hall to hear astronaut John Grunsfeld speak about his role in those repairs. For instance, he and his fellow spacewalkers Mike Massimino and Drew Feustel removed several electrical circuits from Hubble’s Advanced Camera for Surveys (ACS) and replaced them with new ones, put in a new Fine Guidance Sensor (an instrument the size of a baby grand that helps Hubble point its nose in the right direction), and installed new insulation on the telescope’s external surface to protect it from crazy space temperatures—ranging from -200 degrees Fahrenheit to +200 degrees Fahrenheit.

I’m posting this particular image because it’s one Grunsfeld showed in his talk, and it illustrates a really neat astronomical phenomenon. Sometimes, he explained, two galaxies that are close enough together start to literally tug on each other’s hearts, exchanging gases and other matter in a beautiful, slow-motion collision. Eventually, this causes the galaxies to merge and form a single nucleus. If you look closely, you can see this process happening in the image above, which shows five galaxies known collectively as Stephan’s Quintet. The middle two galaxies are involved in a merger. There are two bright spots of light very close to each other, and two fainter tails swirling off to the top and the bottom. Inside those tails, huge numbers of new stars are being born:one of the neat side-effects of galactic mergers.

Oh! And the best part? At least for me, because I hadn’t heard about this before? Grunsfeld also explained that Earth’s own galaxy, the Milky Way, is thought to be involved in the same kind of dance with the Andromeda Galaxy. If and when we do collide with Andromeda, things could get pretty weird. Both the Earth and the Sun are likely to get spun out into the boondocks of the new, bigger galaxy, where—if anyone is still there to see it—the night sky would burn a hundred times brighter with the light of all those extra stars. Don’t worry, though. We’ve still got a couple of billion years to prepare for it.

If you weren’t there on Wednesday in Chicago (and really, what are the odds you were?), you might enjoy this video of the first spacewalk on the 2009 repair mission.

In case you hadn’t noticed, Inkling really likes stories about space.