The world's population will reach seven billion on October 31, 2011, according to the United Nations, and media outlets are heralding the issue of overcrowding on the planet. How long did it take for this many humans to be born?

Planets, including the earth, generate magnetic fields that encompass the space around them. Observations have shown that, like earth's, the planet Mercury's magnetic field is rapidly breaking down, and NASA's Messenger spacecraft confirmed that again earlier this year.

If the planets in the solar system are billions of years old, why do these magnetic fields still exist?

In 2008, excavations in a South African cave uncovered two red-stained abalone shell bowls along with various tools in what was evidently a workshop where ochre and other ingredients were mixed, most likely for use as paint. Researchers examined the artifacts and have published a study in which they say the artifacts are 100,000 years old. Could they really be that ancient?

NASA's Messenger spacecraft mission to Mercury has given scientists the opportunity to learn more about the properties of the solar system's innermost planet. After supposedly billions of years since its formation, the planet should be dead, or geologically inactive. New data from Messenger, however, show that Mercury remains active and is still generating surface features.