Category Archives: evolution of galaxies

More Rainy Day Astronomy

the Antennae galaxies
the Antennae galaxies

In an entry a long time ago I talked about what to do when the skies are clouded out from rain, snow, smog, light pollution, or whatever else it is that keeps you from stepping out for some stargazing. Reading books is always a cool thing. Right now I’m making my way through Alan Guth’s “The Inflationary Universe,” wherein he explains the birth of the universe. I got started on that because of a conversation I had with a friend a few weeks back about the incredible occurrence of the creation of the cosmos and how science explains it. So, my current “rainy day” activity (and late nights, and Saturday afternoons) is all Steve’s fault. (Steve, you know who you are.)

But, if you aren’t in the mood for a good book, there’s always Web surfing. As usual, there are a great many really cool Web sites that talk about astronomy and space science. I’ve talked about the The Astronomy Picture of the Day, and of course Phil Plait’s Bad Astronomy Web site with its attached forum discussion area. And of course, I have mentioned the Gemini Observatory web site, which is being revamped before ourvery eyes. These are in addition to the wonderful sites I’ve linked to over in the left column that take you to the European Southern Observatory and the Hubble Space Telescope Science Institute.

So, there’s no shortage of places to go. Just for grins, here are a couple of new ones for you to explore. The first is the Spitzer Space Telescope. Here’s a little taste to whet your appetite for this new observatory’s work.

The other web page is a subset of the Haystack Observatory educational tutorial website, which contains a lovely radio astronomy “short course” you can browse through to learn a little about the fascinating science being done with the world’s radio dishes and networks. Next time you’re stuck indoors, give it a whirl!

Exploring the Galaxies

The past few months I’ve been working with the Gemini Observatory, doing a series of interesting and absorbing projects for their outreach team. These range from science reports and newsletters to press release edits and consultations. A couple of weeks ago they sent me this great image of members of Stephan’s Quintet, a troupe of five galaxies that lies about 300 million light-years away. What we see here tells an interesting tale of galactic intrigue.

Courtesy Gemini Observatory
Courtesy Gemini Observatory

Some members of the group are interacting with each other, tearing huge swaths of gas and stars away from each other in a sort of cosmic dance. One thing that really stands out in this image is a collection of brilliant red clumps in the spiral galaxy NGC 7320 (just above the center of the image). These are star-forming regions as seen with the help of a special filter.

This galaxy may or may not be part of the Quintet—its relation to the other galaxies in the cluster is the subject of some controversy. Most astronomers now think that NGC 7320 is quite some distance away from the others. Spectroscopic data show its apparent velocity away from us at around 800 kilometers per second. The rest of the group is moving away from us (through the expansion of the universe) at over 6,000 kilometers per second. This puts the the other galaxies in the cluster almost 8 times farther away from us than the brilliantly-lit spiral.

The interacting members of Stephan’s Quintet will continue their dance for millions of years, but eventually they will combine into a different, smaller set of objects than we see today.