We learned that Mercury is just over four and a half billion years old

Sindya N. Bhanoo writes in the New York Times about what NASA’s Mercury Messenger learned before it crashed.

Mercury, like all of the planets in our solar system, is just over four and a half billion years old.

The data were gathered by NASA’s Messenger, a small spacecraft that orbited Mercury for four years before crashing into the planet on April 30. The spacecraft measured the magnetism of rocks on Mercury’s surface.

Read more here.