Across
1
Icy body with a tail near the sun
3
Infectious microscopic agent
4
Natural satellite of Earth
6
Positive particle in nucleus
8
Second lightest element
Down
2
Ball of burning gas in space
3
Hottest planet in solar system
4
Measure of matter in an object
5
Nerve cell in the brain
7
Smallest unit of an element
9
Preserved remains of ancient life