Question: could the earth freeze over

Steven Thomson answered on 15 Jun 2015:

We’ve had ice ages before when most or all of the Earth has frozen, and it’s not impossible that it could happen again. Particularly if the Earth somehow was moved further from the Sun, or if our atmosphere changed and didn’t let as much sunlight through, it could lead to a drop in global temperatures and freeze the surface of the Earth.

I wouldn’t worry too much about it, though – it’s not something that could happen quickly and it’s unlikely to happen any time soon!