Across
1
Mass per unit volume
5
Center of an atom or cell
7
Our home planet
8
Path of a planet around the sun
9
Group of similar cells
11
The Red Planet
14
Blocking of light by a celestial body
Down
2
Chemical element in table salt
3
Curved glass that refracts light
4
Second lightest element
6
Substance with pH above 7
10
Unit of energy
12
Glass that splits light into spectrum
13
Tectonic landmass section