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Moon, Venus, and Mars

September 9, 2015

Modern-day Mars is bitterly cold, and drier than any desert here on Earth. But there’s abundant evidence that conditions were much more pleasant in the distant past. Ancient riverbeds wiggle across its surface, for example, and the Mars rovers have found rocks that formed in a watery environment.

But a team of researchers recently suggested that the young Mars might not have been quite so balmy.

The researchers modeled conditions on Mars about three billion to four billion years ago. Their work suggested that a scenario in which the planet was cold and icy was most likely to explain the present-day Martian surface.

The team’s model considered several factors. One is that the young Sun probably was fainter than it is today. With less sunlight coming in, it’s less likely that liquid water flowed across the Martian surface.

The model also considered the planet’s tilt on its axis. If Mars were lying almost on its side, ice would accumulate at the present-day equator. Volcanic eruptions or asteroid impacts could have melted some of the ice, allowing it to carve the channels and lakebeds we see today.

The model leaves a lot of questions unanswered. But it suggests that there’s still a lot to learn about early Martian history.

And the planet is part of a pretty trio at first light tomorrow. It looks like a faint star to the left or lower left of the Moon. Venus, the brilliant “morning star,” stands to the upper right of the Moon.


Script by Damond Benningfield, Copyright 2015

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