space rocks

Life on Earth first came out of the oceans, but the water itself may have originated from extraterrestrial space rocks. A new study points to a turbulent period when the solar system's giant planets hurled chunks of icy rubble in Earth's direction.

This goes against the more favored scientific theory that Earth's oceans and atmosphere formed from elements within the planet interior, around 4.5 billion years ago. The Nature study argues that the primordial temperatures never dropped enough to condense both volatile elements and water alike, and that the waters of our blue planet must have arrived during a later period of planet building, about one hundred million years after Earth was formed.

Congress charged NASA with finding 90 percent of nearby space rocks greater than 140 meters (460 ft) by 2020. Now the National Research Council warns that the space agency will fall short of that goal without more funding.

In 2009, Canada plans to launch a suitcase-sized spacecraft that will be charged with spotting asteroids that could be on a collision course with Earth. There's already a big ground-based program underway. NASA regularly identifies and tracks asteroids, calculating the likelihood that they could at some point run into our pale blue dot.

Make sure you dont miss this one. Asteroid 2007 TU24 will be as close to Earth as it has been in 2,000 years, and it wont get any closer in this century. With a diameter of around 800 feet, the space rock is large enough to cause some serious damage if it was ever to strike our pale blue dot, but astronomers say that is not a possibility.