During four years of operations, the InSight lander recorded more than 1300 “marsquakes” -- events that sent sound waves rumbling through the planet. Like this one, many were triggered by space rocks slamming into Mars. Others were caused by Mars itself. They’ve all helped scientists refine their models of how Mars is put together.

InSight shut down at the end of 2022. Its main instrument was a seismometer it placed on the surface to record the marsquakes. The way the sound waves rippled through the planet revealed details about its interior.

They showed that the crust is thinner than expected, for example, and there’s less difference between the crust in the northern and southern hemispheres.

InSight also showed that pools of molten rock lie below large volcanic regions -- perhaps indicating that the volcanoes aren’t quite dead.

The lander also revealed that the planet’s core is more than 2200 miles in diameter -- bigger than thought. That means it must contain a lot of lightweight elements, and it must still be molten.

Scientists haven’t finished analyzing InSight’s readings -- and they won’t for years. But they’ve already gotten a better picture of the interior of the Red Planet.

Look for Mars close to the left of the Moon early this evening. It looks like a modestly bright star. Venus, the “evening star,” is below the Moon, with fainter Mercury off to the lower right of Venus.
 

Script by Damond Benningfield

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