Unit 2: Asteroids, Comets, Meteors

Vocabulary flashcards for key terms from the notes on asteroids, meteors, comets, the Kuiper Belt, and Halley’s Comet.

Asteroid

A rocky, metallic object that orbits the Sun in the asteroid belt between Mars and Jupiter; also called a planetoid or minor planet.

Asteroid Belt

The region between Mars and Jupiter containing about 40,000 asteroids; may be material that never formed into a planet; Jupiter's gravity helps keep asteroids from moving into the inner planets.

Planetoid

Another term for a small planetary body; typically used for asteroids.

Meteoroids

Broken pieces of asteroids.

Meteor

A meteoroid that enters Earth's atmosphere; visible as a ‘shooting star.’

Meteorite

A meteor that reaches Earth's surface.

Comet

A rocky, icy, metallic, dusty celestial body that orbits the Sun; has a nucleus, coma, and tail; often called a dirty snowball.

Nucleus (Comet)

The solid center of a comet.

Coma

The blob of gas surrounding a comet's nucleus.

Tail (Comet)

The stream of gas and dust trailing a comet as it orbits the Sun.

Kuiper Belt

A region beyond Neptune from which comets originate; objects there orbit the Sun.

Halley’s Comet

A famous comet named after Sir Edwin Halley; orbits the Sun about every 76 years on average, with major planets' gravity altering its revolution.