Astronomy Chapter 11 Vocab

Front 1

achondrite

Back 1

A meteorite lacking chondrules, associated with larger bodies whose gravity and internal heating has caused them to differentiate.

Front 2

asteroid

Back 2

A small, generally rocky, solid body orbiting the Sun and ranging in diameter from a few meters to hundreds of kilometers.

Front 3

asteroid belt

Back 3

A region between the orbits of Mars and Jupiter in which most of the Solar System's asteroids are located.

Front 4

carbonaceous chondrite

Back 4

A type of meteorite containing many tiny spheres (chondrules) of rocky or metallic material stuck together by carbon-rich material.

Front 5

chondrite

Back 5

A meteorite containing small spherical grains called chondrules.

Front 6

chondrule

Back 6

A small spherical grain embedded in a meteorite.

Front 7

coma

Back 7

The gaseous atmosphere surrounding the head of a comet.

Front 8

dust tail

Back 8

A comet tail containing dust that reflects sunlight; the dust is expelled from the nucleus of the comet.

Front 9

fluorescence

Back 9

The conversion of ultraviolet light (or other short-wavelength radiation) into visible light.

Front 10

ion tail

Back 10

A stream of ionized particles evaporated from a comet and then swept away from the Sun by the solar wind.

Front 11

Kirkwood gaps

Back 11

Regions in the asteroid belt with fewer than the average number of asteroids. The gaps result from the gravitational force of Jupiter removing asteroids whose orbits have periods that are a simple fraction of Jupiter's period.

Front 12

Kuiper belt

Back 12

A region from which some comets come. The regions appear to extend from the orbit of Neptune, past Pluto, out to approximately 55 AU.

Front 13

meteor

Back 13

The bright trail of light created by small solid particles entering Earth's atmosphere and burning up. A "shooting star."

Front 14

meteorite

Back 14

The solid remains of a meteor that falls to Earth.

Front 15

meteoroid

Back 15

The technical name for the small, solid bodies moving within the Solar System. When it enters our atmosphere and heats up, the trail of luminous gas it leaves is called a meteor. When the body lands on the ground, it is called a meteorite. ("A meteoroid is in the void. A meteor above you soars. A meteorite is in your sight.")

Front 16

meteor shower

Back 16

An event in which many meteors occur in a short space of time, all from the same general direction in the sky.

Front 17

near-Earth object

Back 17

An asteroid with an orbit that crosses Earth's orbit or comes close to it.

Front 18

nucleus

Back 18

The core of an atom around which the electrons orbit. The nucleus has a positive electric charge and constitutes most of an atom's mass.

Front 19

Oort cloud

Back 19

A vast region in which comet nuclei orbit, it lies far beyond the orbit of Neptune.

Front 20

radiant

Back 20

The point in the sky from which meteors in showers appear to come.

Front 21

radiation pressure

Back 21

The force exerted by radiation on matter.

Front 22

short-period comet

Back 22

A comet whose orbital period is shorter than 200 years

Front 23

solar wind

Back 23

The outflow of low-density, hot gas from the Sun's upper atmosphere. It is partially this wind that creates the tail of a comet, by blowing gas away from the comet's immediate surroundings.

Front 24

tail

Back 24

The plume of gas and dust from a comet. The plume is produced by the solar wind and radiation pressure acting on the comet. The tail points away from the Sun and gets longer as a comet approaches perihelion.

Front 25

trans-Neptunian object (TNO)

Back 25

Numerous small, icy objects orbiting in the outer part of the Solar System beyond the orbit of Neptune.