Questions answered in this episode:

"If we were to add a lot of mass to the moon, for its gravity to get stronger, what would that mean to the rotation of the earth?" - Barrows0re

"If smaller objects are being pulled by larger objects, then why does the moon get further and further away from earth?" - Draftgon

"Why are celestial bodies always spherical in shape? i.e stars, planets, moons." - AzA

Submit your questions for the next round of Ask the Experts by clicking here and posting in the YouTube comments (Google account required). And while you're there be sure to subscribe to our Spacelab channel for weekly videos on space and astronomy. 

The question with the most "likes" will be answered in the next video by a new guest expert. Previous episodes have featured astronomer Caleb Scharf, astrophysicist Neil deGrasse Tyson and Scientific American's own editor in chief, Mariette DiChristina.