Moon and Mars
If you like volcanoes that are tall and skinny, stay right here on Earth. If you like them short and wide, Venus is your best bet. But if you like them tall and wide, then the place to visit is Mars. Its biggest volcano is twice the height of Mount Everest, and it covers an area as big as Missouri. Several other Martian volcanoes also dwarf anything on Earth.
The volcanoes appear to be dormant now, but Martian volcanoes have been busy in the past. In fact, there's evidence that Mars has undergone five periods of massive volcanic eruptions over the last 3.8 billion years. Each bout repaved a good-sized slab of the Martian surface.
Scientists found evidence of these volcanic eras in pictures from a European orbiter called Mars Express. The scientists counted small craters all across the planet. The craters are gouged by the impacts of small asteroids. Areas with more craters have older terrain.
The counts suggest that there were five major eras of volcanic activity on Mars. The most recent took place around a hundred million years ago.
That doesn't mean that nothing has happened since then. In fact, there's evidence of volcanic eruptions within the last few thousand years. But the eruptions were much smaller than the great events that repaved parts of the Red Planet.
Mars is in good view tonight. Look for it quite near the Moon. They're in the west at nightfall, with Mars just a little to the Moon's right or upper right.
Script by Damond Benningfield, Copyright 2008
For more skywatching tips, astronomy news, and much more, read StarDate magazine.