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Mars Opposition II

May 19, 2016

If you walk through a field of mature dandelions on a windy afternoon, you’ll see thousands of little seed pods wafting on the breeze. And a stronger wind carries away more seeds.

In a way, the same thing is happening on Mars. The solar wind is blowing away particles of the planet’s atmosphere, with gustier winds carrying off more particles. Over the eons, that process has blown away most of the atmosphere.

Today, Mars is cold and dry, and its air is quite thin. But the planet was much warmer and wetter in the distant past, with a thicker atmosphere. Scientists are trying to understand where the air and water went.

Their latest tool is MAVEN, a spacecraft that’s been orbiting Mars for a year and a half. It’s monitoring the planet’s upper atmosphere and its interaction with the solar wind.

Its observations show that, on average, the solar wind carries away about 15 pounds of charged atoms from the upper atmosphere every minute. But during solar storms, the rate goes up dramatically. And since the young Sun was more active than it is today, it generated stronger winds, which must have carried away much more of the Martian atmosphere. Over time, that depleted most of the atmosphere — leaving Mars cold and dry.

Look for bright orange Mars in the southeast as night falls. It arcs across the south during the night, and sets around sunrise.

We’ll have more about Mars tomorrow.


Script by Damond Benningfield

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