Comets, Asteroids, and Meteors
Comets, Asteroids, and Meteors
Comets
• Made of ice, rock, and other organic materials. Sometimes called a dirty snowball
• Has Nucleus, coma, and two tails (dust and ion/plasma tail)
• Nucleus is actual body of rock and ice; varies in size, and ranges from .5 to 25 miles across
• Coma is gas and dust that surrounds nucleus like an atmosphere
• Ion tail is charged gasses, and dust tail is mixture of dust and gas from nucleus breaking down. Both tails can be many millions of miles long. Ion tail glows fluorescently, and dust tail reflects light from sun.
• Usually easier to see dust tail. Both tails always point away from sun. This is due to solar wind.
• Comets come from either the Oort cloud or the Kuiper belt. The Kuiper belt is closer than the Oort cloud. Comets that come from the Kuiper belt have orbits that take less than 200 years to orbit the sun. Comets that come from the Oort cloud take more than 200 years to orbit the sun.
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Asteroids
• Rocky or metallic (sometimes a combination) bodies that orbit the Sun. Metals are Iron and nickel.
• Sometimes called minor planets or planetoids—doesn’t have an atmosphere
• Size can range from a small pebble to hundreds of miles wide
• Largest known has a diameter of more than 500 miles—named Ceres discovered by Piazzi in 1801.
• Ceres is now considered a dwarf planet as well as an Asteroid
• Most found in asteroid belt between Mars and Jupiter
• Thought to be left over from formation of universe
Meteors
• Fragments of comets, asteroids, moons, or planets that have broken off
• Sometimes called shooting stars
• Meteor showers usually occur when Earth passes through a comets orbit
• Most meteors are about the size of a match head, but they can be as big across as a mile
• If a meteor is able to get past the Earth’s atmosphere and impact the Earth it is called a meteorite. Meteorites actually hit the earth’s surface.
• We also have what are called Meteoroids. They are similar to asteroids because they are “floating” out in space. They don’t burn up in our atmosphere, and don’t hit Earth’s surface. They just travel around the solar system.
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