Comets and Meteorites

Flashcards covering vocabulary related to comets, meteorites, and related space phenomena.

Comet

A body of ice and rock typically orbiting the Sun in a highly eccentric orbit.

Asteroids

Formed inside the frost line and are primarily rock and metal, most are in the asteroid belt.

Comets

“Dirty ice balls” that formed beyond the frost line and made primarily of ice, rocks, and rock dust.

Kuiper Belt

Disk shaped region from about 30 to 50 au containing small bodies (dwarf planets and comets) made primarily of rock and ice.

Oort Cloud

A spherical region at the outer limits of the Solar System with a radius about 50,000 to 100,000 au that is hypothesized to contain trillions of comets.

Short-period comet

A comet that originated in the Kuiper Belt and has an orbital period less than 200 years.

Long-period comet

A comet that originated in the Oort cloud and has an orbital period from 200 years to millions of years

Comet Nucleus

The solid, main body component of a comet.

Coma (of a comet)

Visible nebulous envelope that forms around the nucleus of a comet when it passes close to the Sun.

Ion (or plasma) tail

Ionized sublimated gas from the comet that is blown directly away from the Sun by the solar wind.

Dust tail

Trail of dust and small grains of particles pushed away from the nucleus and coma by the Sun’s radiation pressure.

Meteoroid

A rock ranging in size from a grain of sand to a boulder and orbiting the Sun.

Meteor

A meteoroid that has entered a planet’s atmosphere at very high speed, causing a streak of light or a fireball.

Meteorite

A rock that was a meteoroid that strikes a planet or lunar surface.

Micrometeorites

Extraterrestrial particles, ranging in size from 50μm to 2 mm, that reach a planet’s surface.