Encounters with Comets, Meteors, and Asteroids
Millions of asteroids and comets lurk among the planets -- left over bits and pieces from the solar system’s formation four and a half billion years ago. Because of them, we live in a dangerous cosmic shooting gallery and impacts still shape the surfaces of the planets and moons. For instance, without warning on Feb. 15, 2013, an asteroid fragment struck Siberia and exploded over a populated area close to the Russian city of Chelyabinsk. Dozens of building- and car-mounted video cameras captured the meteor’s descent and the shadows it cast, making it the most documented meteor event in history. There were no deaths, but about 1,500 injuries occurred, mostly cuts from glass that broke due to the force of the shock wave produced when the meteor broke up in the atmosphere. Sound waves from this explosion circled the Earth several times.
Meanwhile we have a comet coming our way this fall. Its name is Comet ISON and we think it has never been sunward before. For billions of years this icy rock has probably floated in the Oort Cloud, far beyond the planets. Perhaps an impact with another ice ball sent Comet ISON sunward. It was discovered in the fall of 2012 and we have been waiting to see it up close for over a year.
Comet ISON is a sungrazer, a comet whose orbit takes it within a solar diameter of the sun’s surface. The sun vaporizes a comet’s gases and pushes away the comet’s dust to create a spectacular tail. The closer a comet comes to the sun, the greater the effect, unless the comet comes too close. The sun can make Comet ISON very bright, break it into a few pieces that could also be spectacular, or completely destroy the comet. Comet ISON’s close approach to the sun occurs on Thanksgiving Day. On the following day, we will know if we have a fantastic comet to watch over the holidays or if the comet has disappeared.
The planetarium’s new IMPACT! show includes an update on Comet ISON and the latest discoveries about the comets and asteroids that lurk in our neighborhood.