Summary: Mars is passing in front of the center of the Milky Way galaxy this week. The planet looks like a modest orange star in the southwest in early evening, above the “spout” of teapot-shaped Sagittarius. The galaxy’s center is about 27,000 light-years beyond Mars, and it’s hidden behind billowing clouds of interstellar dust. One of those clouds is just a few hundred light-years from the center itself. Known as Sagittarius B2, it’s one of the busiest stellar nurseries yet discovered — it’s giving birth to thousands of new stars. It’s also a busy molecule factory. In fact, just about every molecule that’s been detected anywhere in space has been seen in Sagittarius B2. The most complicated molecules may form on the surfaces of the cloud’s dust grains. Simple molecules may stick to these grains, which may be coated with thin layers of ice. Over time, the molecules migrate across the dust grains, allowing them to link up. When the dust grains pass close to a newborn star, their ice vaporizes, releasing the new molecules into space. The list of molecules includes some of the precursors of life, such as some types of sugars. One of the most complicated yet seen is glycolaldehyde. It can link with another sugar to form a key molecule in RNA and DNA, which contain the genetic code of life. Glycolaldehyde was recently seen around a young star — a discovery with implications for life on other worlds. More about that tomorrow. Script by Damond Benningfield, Copyright 2012 For more skywatching tips, astronomy news, and much more, read StarDate magazine.
