Across
1
Positive particle in nucleus
4
Our home planet
5
Tissue that contracts for movement
7
Nerve cell in the brain
9
Ball of burning gas in space
10
Force that attracts objects together
12
Particle of light
13
Substance with pH below 7
Down
2
Path of a planet around the sun
3
Element found in all living things
6
Mass per unit volume
8
Measure of matter in an object
11
Glass that splits light into spectrum
14
Hottest planet in solar system