Astronomy Vocabulary

Any pattern of stars recognizable in Earth's night sky. May be part of a constellation or may be composed of stars from more than one constellation.

A

A minor planet orbiting the Sun, consisting of metal and rock.

A

A concentration of mass so compact that it creates a region of space from which not even light can escape.

B

A body of ice and rocky debris, typically a few miles across, that orbits the Sun in a long ellipse.

C

A region on the celestial sphere surrounding a specific and identifiable grouping of stars.

C

Sunlight reflected by Earth that makes the otherwise dark part of the Moon glow faintly.

E

An event that occurs when the shadow of a planet or moon falls upon a second body.

E

The two times each year when the Sun is directly overhead at noon as seen from Earth’s equator.

E

A vast collection of stars, gas, and dust, typically 10,000 to 100,000 light-years in diameter and containing billions of stars.

G

A glow in the night sky or around one’s observing site caused by artificial light and greatly reducing the number of stars that are visible.

L

The distance that light (moving at about 186,000 miles per second) travels in one year, or about 6 trillion miles.

L

A brief streak of light caused by a small piece of solid matter entering Earth’s atmosphere at tremendous speed (typically 20 to 40 miles per second).

M

A broad, faintly glowing band stretching across the night sky, composed of billions of stars in our galaxy too faint to be seen individually.

M

An interstellar cloud of dust, hydrogen, helium, and other ionized gases.

N

The gravitationally curved trajectory of an object, such as the trajectory of a planet around a star or a natural satellite around a planet.

O

A type of astronomical body orbiting a star or stellar remnant which is massive enough to be rounded by its own gravity (but not massive enough to achieve thermonuclear fusion) and has cleared its neighbouring region of all planetesimals.

P

A highly magnetized rotating neutron star or white dwarf that emits a beam of electromagnetic radiation.

P

A supermassive black hole gorging on gas at the center of a distant galaxy.

Q

The two times each year when the Sun is farthest north or south in the sky.

S

A massive ball of gas that generates prodigious amounts of energy (including light) from nuclear fusion in its hot, dense core.

S

A collection of stars orbiting a common center of mass.

S

A temporary dark blemish on the surface of the Sun that is a planet-size region of gas cooler than its surroundings.

S

A star ending its life in a huge explosion.

S

A type of stellar remnant composed mostly of electron-degenerate matter, and lacking the mass needed to continue the nuclear fusion process with its constituent atoms, so the object's energy output normally comes from radiative cooling.

W

The set of constellations situated along the ecliptic in the sky, through which the Sun, Moon, and planets move.

Z