Comets, asteroids and meteoroids are plentiful in the asteroid belt and Kuiper Belt regions of the solar system, and every once in a while, they venture near Earth.
Asteroids, Comets, Meteoroids: What’s the Difference?
Comets (from the Latin name stella cometa, meaning “hairy star”) are made up of rock, ice and other elements. They originate in the Kuiper Belt region beyond Neptune and in an even more distant region called the Oort Cloud. Comets have an elliptical orbit around the Sun and are known for their “tails,” comprised of the dust and gas that melts off the comet as it nears the sun. The force of solar winds are such that so a comet’s tail always points away from the sun.
Asteroids are large chunks of rock that come from the asteroid belt region between Mars and Jupiter. Asteroids range wildly in size, from very tiny objects to rocks hundreds of kilometers across. According to NASA, the pull of Jupiter’s gravity or collisions with other asteroids cause some to get thrown out of orbit. These wandering asteroids have been known to intersect with other objects in the solar system, including the Earth.
The Study of Space Debris
The first U.S. mission to bring back samples from a comet was Stardust. Launched in 1999, Stardust encountered an asteroid, Annefrank, and a comet, Wild 2, before returning to Earth in 2006.
Viewing Comets, Meteor Showers and Asteroids
The Harvard-Smithsonian Center for Astrophysics has a monthly report on the night sky and will help you figure out what planets and comets are visible, as well as alerting you to any upcoming meteor showers. Heavens-Above lists the locations of the planets and minor planets, as well as any comets currently brighter than magnitude 12 in the night sky.
Click on the name of your city (or any city you are curious about) on Your Sky and get a sky map of the area that shows the visible constellations and planets. You can also set preferences for what objects you’d like to see.