* Astronomy

"This month, some big space rocks have been hitting Earth's atmosphere. There have been five or six notable fireballs that might have dropped meteorites around the United States" - Bill Cooke, NASA's Meteoroid Environment Office.

It's not the number of fireballs that has researchers puzzled. So far, fireball counts in February 2012 are about normal. Instead, it's the appearance and trajectory of the fireballs that sets them apart.

Read more