A galaxy shaped like a round or flattened ball, generally containing only old stars
A large group of single stars, star systems, star clusters, dust and gas bound together by gravity
A force that moves rocks and other materials downhill, the force that pulls objects towards each other
The spinning motion of a planet on its axis
The name often given to the four outer planets, Jupiter, Saturn, Uranus and Neptune
A model of the solar system in which Earth and the other planets revolve around the sun
The name often given to the four inner planets, Mercury, Venus, Earth and Mars
A chunk of rock or dust in space
A meteoroid that passes through the atmosphere and hits Earth’s surface
A doughnut-shaped region that stretches from around Pluto’s orbit to about 100 times Earth’s distance from the sun
The movement of an object around another object
The two days of the year on which neither hemisphere is tilted toward or away from the sun
All of space and everything in it
The blocking of sunlight to Earth that occurs when the moon is directly between the sun and Earth
One of the different apparent shapes of the moon as seen from Earth
A loose collection of ice, dust, and small rocky particles, typically with a long, narrow orbit of the sun
The initial explosion that resulted in the formation and expansion of the universe
The path of an object as it revolves around another object in space
The daily rise and fall of Earth’s waters on its coastlines