Comets, Asteroids, & Meteoroids

SPI 6.1 Use data to draw conclusions about the major components of the universe.

Comets, Asteroids, & Meteors The solar system contains many other types of objects, including comets, asteroids, and meteoroids.

Comets A comet is a small body of ice, rock, and cosmic dust loosely packed together. Known as “dirty snowballs.”

When a comet passes close enough to the sun, solar radiation heats the water ice so that the comet gives off gas and dust in the form of a long tail. The ion tail consists of electrically charged particles of gas. Comets

Comet Orbits The difference between the orbit of a planet and the orbit of a comet is that a comet's orbit is highly elliptical and a planet's orbit is only slightly elliptical, but more circular.

Comet Orbits The comet’s ion tail always extends away from the sun. This is because the ion tail is blown away from the sun by the solar wind.

Asteroids Asteroids are small, rocky bodies in orbit around the sun. Have irregular shapes Asteroids

Asteroids Most asteroids orbit the sun in a wide region between the orbits of Mars and Jupiter, called the asteroid belt.

Meteoroids A meteoroid is a small, rocky body orbiting the sun. Meteoroids are similar to asteroids, but they are much smaller.

Meteoroids In fact, meteoroids probably come from asteroids.

Meteor As it burns up, the meteoroid glows red hot and gives off an enormous amount of light. From the ground we see a streak of light or shooting star. The bright streak of light caused by a meteoroid or comet dust burning up in the atmosphere is called a meteor.

Meteorite If a meteoroid enters Earth’s atmosphere and strikes the ground, it is then called a meteorite. It travels at such high speeds that it heats up and melts. Meteorites that hit the ground can cause craters.

Meteorite Crater Planets and moons that have no atmosphere have many more impact craters than those that do have atmospheres. Earth’s atmosphere acts like a shield.