[music playing]NARRATOR: Earth-- a 4.5-billion-year-old planetstill evolving.As continents shift and clash, volcanoes erupt,and glaciers grow and recede.The Earth's crust is carved in countless ...

During Earth's ancient Snowball periods, when the entire planet was wrapped in ice, life may have endured in tiny meltwater ponds on the surface of equatorial glaciers. MIT researchers discovered that ...

Water is essential to life as we know it, but scientists are still unsure about how it originated on Earth. One theory is that asteroids express-shipped us hydrogen, essential to the formation of ...