A crisp autumn day is a perfect time for a walk — cool, dry air and bright sunshine. And if you walk in a park or on a country lane, you might kick up a little bit of dust, too.
Dust is one thing shared by every body in the solar system with a solid surface. But the type of dust, and the way it’s formed, are quite different.
As two examples, consider the Moon and Mars, which are in good view at first light tomorrow. Mars looks like a bright orange star a little to the left of the Moon.
We’ve already seen the dusty results of a stroll on the Moon. After a few hours out on the lunar surface, some of the Apollo astronauts looked like they’d been rolling in mud — their white spacesuits turned dingy gray.
The entire Moon is covered with dark, powdery dust. It’s created by a constant “rain” of space rocks. Their high-speed collisions pulverize rock at the surface, churning it to fine-grained dust. The dust is dangerous — it could short out electronics, gum up mechanical systems, and even harm the lungs of those who breathe it.
The dust on Mars is less nasty, but not much. Most of it’s probably the consistency of sand. Some of it is churned up by impacts, but most of it is created by the wind, which erodes the rocks.
Mars dust is yellowy-orange. That’s because it’s rich in iron that interacted with water, forming rust. In the distant future, people may leave their footprints in this orange surface — the dusty surface of Mars.
Script by Damond Benningfield, Copyright 2011
For more skywatching tips, astronomy news, and much more, read StarDate magazine.