The Earth moves around the sun similarly the moon orbits around the Earth.
Is it just that it needs a semicolon b/wn sun and simlarly? That's certainly the most obvious fault, but there are others:
1...Sun and Moon should also be capitalized.
2...I would use the more specific verb "orbits" first.
3..."orbits around" is redundant.
4... There should be a comma after "similarly".
The Earth orbits the Sun; similarly, the Moon (orbits)(moves around) the Earth.