Moon and Mars 
Bright orange Mars keeps company with the gibbous Moon as they saunter low across the southern sky tonight. Mars is close to the left of the Moon at nightfall, and even closer above the Moon as they set in the wee hours of the morning.
Countless craters pockmark the surface of the Moon — the result of billions of years of bombardment by asteroids large and small. And Mars has lots of craters as well.
New craters are still forming on both worlds. A Mars-orbiting spacecraft recently discovered a crater a hundred feet wide on the Red Planet that had formed sometime in the previous three years. And last September, a telescope on Earth saw the flash of an impact on the Moon — an event that gouged a crater about the same size as the one on Mars.
On September 11th, an astronomer in Spain was operating a small telescope that looks for lunar impacts. He saw a brilliant flash in the Sea of Clouds — a volcanic plain in the Moon’s southern hemisphere. The impact was bright enough to see with the unaided eye, so anyone who was looking toward the Moon at that moment would have seen a flash that lasted for a couple of seconds.
The rock that hit the Moon was probably about a yard across and weighed half a ton. Similar-sized rocks slam into Earth as well. But they burn up or explode high in the atmosphere. So it takes a much bigger space rock to gouge a crater on Earth.
We’ll talk about the Moon and another bright companion tomorrow.
Script by Damond Benningfield, Copyright 2014