Across
1
Second lightest element
4
Smallest unit of an element
5
Blocking of light by a celestial body
8
Mass per unit volume
9
Unit of power
11
Unit of electric potential
Down
2
Icy body with a tail near the sun
3
Measure of matter in an object
6
Reddish electrical conductor
7
Ball of burning gas in space
10
Force that attracts objects together