Across
1
Icy body with a tail near the sun
3
Solid with repeating atomic pattern
4
Fourth state of matter
5
Substance with pH below 7
6
Basic unit of life
9
Form of thermal energy
12
Infectious microscopic agent
Down
1
Reddish electrical conductor
2
Amplified beam of light
7
Blocking of light by a celestial body
8
The Red Planet
10
Chemical element in table salt
11
Smallest unit of an element