The Fourth of July last year had some extra fireworks. NASA's Deep Impact spacecraft sent a hefty projectile--more than 800 pounds--into the body of the comet known as Tempel 1. The collision delivered 19 gigajoules of energy--the equivalent of nearly five tons of explosive TNT--into the wandering comet and ejected a plume of its innermost secrets. Roughly 10 million kilograms of comet stuff (more than 22 million pounds) spread out into space, giving scientists a rare glimpse of the ingredients that go into making a comet. Now researchers observing with the Spitzer Space Telescope have revealed their findings: comets contain a mix of materials that formed under widely divergent conditions.
Read more at SCIENCE NEWS -Deep Impact Reveals Comet's Components