Mars at Opposition III

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Mars at Opposition III
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“Polar vortex” is a phrase that’s entered the American lexicon in recent years. It’s a swirling low-pressure system centered on the winter pole. If it becomes unstable, it can sweep outward, bringing bitter misery — something that’s happened a few times here in the northern hemisphere.

Earth isn’t the only planet in the solar system with a polar vortex. Venus has double vortexes at its poles. The vortex around the north pole of Saturn forms a hexagon. And the vortex at the north pole of Jupiter is surrounded by a half-dozen other cyclones, so the whole array looks like a pan of cinnamon rolls fresh out of the oven.

The poles of Mars are encircled by vortexes as well. They’re elliptical — like squashed circles. The transition zone around them is turbulent, and plays a role in circulating dust around the planet. But the vortexes themselves seem to be pretty stable.

Studies suggest the vortexes form when carbon dioxide in the atmosphere freezes on or around the pole where it’s winter. The process pumps energy into the atmosphere, which powers the vortex. And it happens so quickly that the vortex is stable — it doesn’t have time to wobble around. That keeps the coldest air locked near the poles.

And Mars is shining at its best this month. It’s low in the east at nightfall, and looks like a bright orange star. It arcs across the south during the night, and is low in the west at first light.

We’ll have more about Mars tomorrow.

Script by Damond Benningfield

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