Comets, Meteors, and Asteroids

Comets

Small celestial bodies that orbit the Sun. They are made of ice, dust, and rocky materials.

Nucleus

A solid, icy core made of rock and dust.

Coma

A glowing cloud of gas and dust that surrounds the nucleus when a comet is close to the Sun.

Hydrogen cloud

A diffuse cloud of neutral hydrogen gas that surrounds the nucleus of a comet.

Dust tail

• Up to 10 million km long

  Made of small particles of dust and gas.

• It’s curved and follows the comet’s path.

• It forms due to the solar wind pushing dust particles away from the come

ion tail

• 100 million km long

• Made of charged particles (ions) that are blown directly away from the Sun by the solar wind.

• It’s straight and points directly away from the Sun.

• Often appears bluish due to ionized gas.

Short term comets

• most originate in region beyond Neptune called Kuiper belt

• approximately circular, prograde orbits 30-100 AU

• normally orbit outside jovian planets, occasionally kicked into inner solar system

Long term comets

• most in Oort cloud (up to 50,000 AU from Sun)

• normally orbit far from the Sun, very few enter planetary region of solar system highly elongated orbits

• not confined to ecliptic, all orbital inclinations prograde and retrograde orbits

• roughly uniform distribution