Earth & Space

Vocabulary

AstronomyThe study of the moon, stars, and other objects in space

RotationThe spinning motion of a planet on its axis

AxisAn imaginary line that passes through Earth’s center and the North and South poles, about which Earth rotates

RevolutionThe movement of an object around another object

OrbitThe path of an object as it revolves around another object in space

SolsticeThe two days of the year on which the sun reaches its greatest distance north or south of the equator

EquinoxThe two days of the year on which neither hemisphere is tilted toward or away from the sun

GravityThe attractive force between objects; strength depends on masses of objects and distance between them

InertiaThe tendency of an object to resist any change in its motion

PhaseOne of the different apparent shapes of the moon as seen from Earth

WaxingWhen the Moon changes from new to full (growing)

WaningWhen the Moon changes from full to new (shrinking)

Lunar EclipseThe blocking of sunlight to the moon that occurs when Earth is directly between the sun and the moon

Solar EclipseThe blocking of sunlight to Earth that occurs when the moon is directly between the sun and Earth

TideThe periodic rise and fall of the level of water in the ocean

MeteoroidsA chunk of rock or dust in space

CraterA large round pit caused by the impact of a meteoroid

Solar Systemthe Sun, its eight planets, & other objects that orbit the Sun

Astronomical Unitis about 150 million km, the mean distance from Earth to the Sun

Meteoritesfragments of space material that land on Earth’s surface

Constellationsgroups of stars that form patterns in the sky

Galaxygroup of stars, gas, & dust held together by gravity

Cometlarge body of frozen ice and rock that travels toward the center of the solar system in an extreme orbit