A

accelerate

A change in velocity

atmosphere

The blanket of air around the earth

atom

Tiny building block of matter - too small to see

C

centrifugal

From the Latin word for away from the center

centripetal

From the Latin word for moving toward the center

communication

Sharing of information by talking or other methods

D

debris

Objects no longer used or needed

dense

Thick or containing a large amount of matter in a limited space

displace

Move out of place

E

escape velocity

The speed required to leave gravitational pull

G

Galileo Galilei

Italian scientist who lived in the late 16^th and early 17^th century

gravitational

Related to gravity

gravity

The attraction of two objects of mass

H

helium

A gas that is lighter than most other gases

M

mass

The amount of matter in an object

microgravity

The apparent lack of gravity due to free fall

Milky Way Galaxy

The galaxy that the planet earth and its solar system dwells

O

orbit

The revolving of one object around another

P

pressure

The pushing of one matter on another

proximity

closeness

R

revolve

To move around another object

T

tides

The movement of the ocean level

V

velocity

The speed of an object in one direction

W

wind resistance

The drag or push of air against a moving object