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Starwatch NewsletterMinnesota Starwatch is a newsletter describing the night sky in the Midwest.
It is updated monthly, and is produced by the |
Minnesota Starwatch for March 2008
Hello, this is Minnesota Starwatch for March 2008.
This month Mars is high in the southern sky. When you look at Mars with the naked eye, it clearly looks red compared to the surrounding stars. This is due to iron oxide (rust) in the crust of the planet. You can see the same colors in the American desert southwest or on the cinder cones on the summit of Mauna Kea in Hawaii. But why is Mars so rusty when Earth is not? Mars is much smaller than Earth, only about one tenth as massive. When Earth formed, it was hot enough to melt most of its iron that then sank to the center of the planet in a process called differentiation. But, models suggest that since Mars is so small, it didn't get hot enough during formation to melt all of its iron. This left more iron on the surface that was either already in the form of rust or that was later oxidized by liquid water or by the atmosphere.
Recently the NASA Mars Express probe found some evidence for methane on Mars that appears to be located in the same regions that show the most evidence for water. Methane is a hydrocarbon like propane and ethane and is an organic molecule, meaning it contains carbon. This is important because on Earth, methane is produced mostly by the decay of organic matter such as cow dung and rotting plants in bogs. There are no cows or bogs on Mars, of course, but the presence of methane associated with water could be indicative of some sort of sub-surface life processes. The detection of methane on Mars is considered very uncertain, but already there are plans to equip future missions to Mars with instruments that are much more sensitive to detecting methane than Mars Express.
Another bright object in the night sky just a bit to the east of Mars is Saturn. The rings of Saturn, which can easily be seen with a pair of binoculars, are slowly approaching edge-on this year and will be exactly edge-on next spring. Although this makes the rings less spectacular to look at, it does make it easier to see some of the many satellites of Saturn including the massive moon, Titan.
Titan is the only satellite in the Solar System with an atmosphere and as it turns out, its atmosphere happens to be composed primarily of methane. Unlike on Mars, Titan's methane is left over from the formation of the Solar System and was not produced by life. Recent observations by NASA's Cassini spacecraft revealed what appear to be large bodies of liquid on Titan's surface. Since Titan is so far from the Sun, it is far too cold for liquid water, so these lakes and seas are likely filled with liquid methane. In fact, a news release from the Cassini mission suggests that there are probably more hydrocarbons on Titan than in all the oil and gas reserves on Earth!
The evening of March 20th also marks the onset of spring with the vernal equinox. On this day, there will be equal hours of day and night with the days continuing to lengthen until the summer solstice on the 20th of June.
Friday night telescope viewing at the University of Minnesota Astronomy Department begins at 8pm. Please call (612) 626-0034 for more information. The Como Planetarium in St. Paul's Como Park offers limited star shows. For more information, call (651) 293-5398 or check their website at www.planetarium.spps.org.
For fun Astronomy Outreach programs check out our Public Outreach link, or if you're interested in how you can help build the new Minnesota Planetarium, please call 612-630-6151 or visit www.mnplanetarium.org.