Vocabulary
What is the term for a satellite that orbits a planet?
Moon
Who was the first person to suggest that planets travel in elliptical orbits?
Johannes Kepler
Define "galaxy."
A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
Who discovered the four largest moons of Jupiter?
Galileo Galilei
What is the word for the force that pulls objects toward each other?
Gravity
Who is known for the laws of planetary motion?
Johannes Kepler
What is the term used for a spacecraft designed for travel in outer space?
Spacecraft
Name the scientist who developed the theory of general relativity.
Albert Einstein