The Moon anchors a beautiful lineup late tonight. It includes Mars and the two brightest stars of Taurus. The lineup climbs into view by around midnight, and is high in the sky at first light.

Mars glows bright orange — the result of iron-rich dust that coats most of the planet. The major exceptions are the polar ice caps, which are almost pure white.

There’s a lively debate about what’s at the bottom of the cap at the south pole. Some researchers say there could be liquid water mixed with the dirt. Others say that water wouldn’t work — it’s more likely to be clay, salty minerals, or even volcanic rock.

The debate is based on observations made by Mars Express. It used radar to peek below the ice cap, which is made of layers of frozen water and carbon dioxide. The radar showed bright reflections below the ice cap. The original study team interpreted the reflection as liquid water mixed with high levels of salts. A comparison to radar readings of a lake below the ice in Antarctica reached a similar conclusion.

But others say it’s too cold even for salty water, and other materials are a more likely explanation — leaving the ground below the ice cap dry.

Look for Mars close to the right of the Moon. The orange star Aldebaran — the eye of the bull — is farther from the Moon along the same line. And the bull’s next-brightest star, El Nath, is close to the left of the Moon.

More about Mars tomorrow.
 

Script by Damond Benningfield

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