Comets, Asteroids, and Meteors Section 14.5

Standard  6.e. Students know the appearance, general composition, relative position and size, and motion of objects in the solar system.

Introduction  The sun, planets, and moons are the only objects in the solar system. There are other smaller objects moving through the solar system as well.

Comets  Comet: a “dirty snowball” about the size of a mountain.  Comets are loose collections of ice and dust, and small rocky particles whose orbits are usually very long, narrow ellipses.

Comets  A Comet’s Head  Clouds of gas and dust form a fuzzy outer layer called the coma.  Nucleus: the inner core of a comet  The brightest part is the nucleus and the coma

Comets  A Comet’s Tail  Comet means “long-haired star”  Has a gas and a dust tail. Gas tail is always away from the sun.

Comets  Origin of Comets  Kuiper Belt: doughnut shaped region that extends beyond Neptune’s orbit  Oort Cloud: spherical region of comets that surrounds the solar system

Asteroids  Asteroids are too small and too numerous to be considered planets or dwarf planets.  Most asteroids revolve around the sun in circular orbits between Mars and Jupiter.  Called the asteroid belt

Asteroids  Astronomer have found more than 100,000 asteroids.  They hypothesize these asteroids were leftover pieces of the early solar system that never came together to form a planet

Asteroids  Some asteroids have extremely elliptical orbits that cross paths with other planets. This is what happened with the dinosaurs. An asteroid in orbit hit earth, causing a mass extinction.

Meteors  When there is a meteor shower, you often see a meteor at least once every 10 minutes  Meteoroid is a chunk of rock or dust in space

Meteoroids  Meteoroids come from comets or asteroids  When a meteoroid enters Earth’s atmosphere, it is called a meteor. It burns up and creates a streak in the sky (SHOOTING STAR.

Meteors  When meteoroids enter the atmosphere and strikes Earth’s surface, it is called a meteorite.