Across
1
Positive particle in nucleus
2
Measure of matter in an object
5
Tissue that contracts for movement
6
Path of a planet around the sun
7
Ball of burning gas in space
8
Substance with pH below 7
Down
2
Naturally occurring inorganic solid
3
Mass per unit volume
4
Blocking of light by a celestial body
9
Disturbance that transfers energy
10
Basic unit of life
11
Fourth state of matter