... Tonight's Sky . ... An artificial comet holds secrets to Earths life . ... Supernova showered Earth with radioactive debris . ... The Real Reality Show: Would aliens be anything like us? ... NASA study shows asteroid impacts may have accelerated life on Earth . ... An intense asteroid bombardment nearly 4 billion years ago may not have sterilized the early Earth as completely as previously thought, according to a NASA-funded study. ... Satellite to study near-Earth asteroids' wobbly signature . ...