The moon is not as big as the earth to begin with.Toneri launched himself or I believe it was Kurama"s bijuudama anyways he was a KMs away from the moon refer here-
http://www.narutoforums.com/blog.php?b=31025
I want to point out a few mistake that the guy made:
1- He didn't account the moons atmosphere, he was using our moon which is bigger but has less atmosphere than Naruto's moon.
2- he said the Earth's clouds where visible which would mean Toneri was one of the upper layers of Earth's atmosphere.
3- he didn't account the moon was falling towards Naruto's Earth thus forgetting that the distance between Earth and the moon was shortening.
4- The our moon has layers just like the Earth, but they are thinner than the layers of Earth, Naruto's moon having an atmosphere greater than our moon should have layers of atmosphere greater than ours.
5- Toneri is from an alien species... is probably not completely unbeliavable that he can survive in space...but the same can't be said about Naruto who is human.
Bigger than Narutos moon? Pretty sure that Narutos moon is either equal or a bit bigger from the calcs I've seen of it.
Toneri needed sunlight from what I can recall he needed to reach a certain distance to absorb solar energy.
And Narutos moon is six paths chibaku tensei a gravity core also . The fact of the matter is the Naruto moon was later hollowed by hamura and his people because he decided to stay there to guard Juubi.The air only comes from the contents of it.
Hamura didn't need air to begin with .He was on the moon while it had no air.
And I'm pretty sure Naruto is descendant of ootsusukis. And he didn't do that in base form he did that in kyuubi mode so it makes sense.