More Moon and Companions

StarDate: June 17, 2010

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The Moon has some bright companions tonight. As night falls, look for the planet Mars to the upper right of the Moon, the star Regulus to the right, and the planet Saturn farther to the upper left of the Moon.

Earthlings have dispatched more than two dozen spacecraft to Mars. These visitors have mapped the planet in great detail, told us about its composition and its history, and located vast deposits of water beneath the surface.

Mars has also dispatched some visitors to Earth -- visitors that have revealed their own details about the Red Planet.

These visitors are meteorites -- several dozen chunks of the Martian crust that were blasted into space when giant space rocks hit the planet. Most were found atop the ice in Antarctica, or atop the desert sands of the Middle East -- places where there are almost no Earth rocks. In fact, one of the meteorites was first reported 10 years today in the kingdom of Oman.

Scientists identify the origin of the meteorites by analyzing tiny bubbles inside the rocks. The ratio of certain elements in these bubbles matches the ratio measured in the atmosphere of Mars.

The meteorites tell us about the composition of the Martian crust, and about conditions on Mars when the rocks formed. And one team of scientists says that at least three of the meteorites tell us something more: that microscopic organisms once lived on Mars -- their traces preserved in rocks that made their way to Earth.

Script by Damond Benningfield, Copyright 2010

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

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