Space Vocabulary

Axis Imaginary line around which Earth spins, causing day and night; drawn from the north geographic pole to the south geographic pole.

Rotation Spinning of Earth on its axis, which causes day and night; it takes 24 hours for earth to complete one rotation.

Revolution The motion of Earth around the Sun, which takes about 365 and ¼ days, or one year to complete.

Orbit Curved path followed by Earth as it moves around the Sun.

Solstice Time when the Sun reaches its greatest distance north or south of the equator, which occurs June 21st or 22nd for the northern hemisphere. (longest day of the year.)

Equinox Twice- yearly time when the Sun is directly above Earth’s equator and the length of the day equals the length of night worldwide.

Craters Depression formed by a large meteorite; the more craters in a region, the older the surface.

Moon Phases Changing views of the moon as seen from Earth, which are caused by the moons revolution around Earth.

Solar Eclipse Occurs during a new moon, when the Sun, the Moon, and the Earth are lined up in a specific way and Earth moves into the Moon’s shadow.

Lunar Eclipse Occurs during a full moon when the Sun, the Moon, and Earth line up in a specific way and the moon moves into Earth’s shadow.

Solar System Extremely large system that includes the Sun, planets, comets, meteoroids and other objects that revolve around the Sun.

Astronomical Unit Unit of measurement used to determine distances between objects in the solar system; 1 AU equals 150,000,000 km.

Asteroid Small, rocky, space object found in the asteroid belt between the orbits of Jupiter and Mars.

Comet Space object made of rocky particles and water ices; forms a tail when orbiting near the Sun and is found mostly in the Kuiper Belt and the Oort Cloud.

Nebula Cloud of rotating gases and dust particles from which the solar system may have formed about 5 billion years ago.