1.
Astronomy: the study of the earth moon stars and other objects in space
2.
Axis: the imaginary line that passes through the north and south poles
3.
Craters: large round pit caused by the impact of a meteoroid
4.
Eclipse: the partial or total blocking of one object in space by another
5.
Equinox: The two days of the year on which neither hemisphere is tilted toward or away from the sun
6.
Escape velocity: the velocity a rocket must reach to fly beyond a planets gravitational pull
7.
Force: a push or pull exerted on an object
8.
Gravity: attract objects toward each other
9.
Inertia: the tendency of an object to resist in motion
10.
Law of universal gravitation: states that every object in the universe attracts every other object
11.
Lunar eclipse: the blocking of sunlight to the moon that occurs when Earth is directly between the sun and the moon
12.
Maria: dark, flat areas on the moon's surface formed from huge ancient lava flows.
13.
Mass: the amount of matter in an object
14.
Meteroids: chunks of rock or dust from space
15.
Neap tide: a tide with the least difference between consecutive low and high tides that occurs when the sun and moon pull at right angles to each other at the first and third quarters
16.
Newton's first law of motion: says that an object at rest will stay at rest and an object in motion will stay in motion with a constant speed and direction unless acted on by a force.
17.
Orbit: the path of an object as it revolves around another object in space
18.
Orbital velocity: the velocity a rocket must achieve to establish an orbit around a body in space.
19.
Penumbra: the part of a shadow surrounding the darkest part
20.
Phases: the different shapes of the moon you see from Earth
21.
Revolution: the movement of one object around another
22.
Rocket: a device that expels gas in one direction to move in the opposite direction
23.
Rotation: the spinning of a planet on its axis
24.
Rovers: robots that move around on the surface of a planet or moon.
25.
Satellite: an object that revolves around another object in space
26.
Solar eclipse: the blocking of sunlight to Earth that occurs when the moon is directly between the sun and Earth.
27.
Solstice: when the sun is farthest north or south
28.
Space probe: a spacecraft that carries scientific instruments that can collect data but has no human crew
29.
Space shuttle: a spacecraft that can carry a crew into space, return to Earth, and then be reused for the same purpose
30.
Space station: a large artificial satellite on which people can live and work for long periods
31.
Spring tide: a tide with the greatest difference between consecutive high and low tides that occurs when the sun and the moon are aligned with Earth at the new moon and the full moon
32.
Telescope: a device built to observe distant objects by making them appear closer
33.
Thrust: the reaction force that propels a rocket forward
34.
Tide: the rise and fall of ocean water on its coastlines
35.
Umbra: the very darkest part of the moon's shadow
36.
Velocity: speed in a given direction
37.
Weight: the force of gravity on an object
