What is a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction?
a galaxy
15
Which word means the whole cosmic system of matter and energy of which Earth is a part?
universe
15
What is the collection of eight planets and their moons in orbit around the sun, together with smaller bodies in the form of asteroids, meteoroids, and comets called?
the solar system
15
Name the 4 outer planets.
Jupiter, Saturn, Uranus, Neptune
15
What is a celestial body moving in an elliptical orbit around a star?