There is an article that I really like - Earth's Moon is Rare OddBall. Our moon was formed right after a huge planetary collsion with young Earth about 4 billion years ago. Guess what? Only about one in year 10 to 20 solar systems may have a similiar moon. Does that mean that there are about 5 to 10 percent of planetary systems that have that kind of moon? You do the math.
Here's the quote that I copied from the article :
"When a moon forms from a violent collision, dust should be blasted everywhere," said Nadya Gorlova, an astronomer at the University of Florida in Gainesville who analyzed the telescope data in a new study. "If there were lots of moons forming, we would have seen dust around lots of stars. But we didn't."
What do you think???
For further reading, click on the link below.
Earth's Moon is Rare Oddball