Question: why is gravity different in different parts of the world?

James Verdon answered on 29 Jun 2012:

Hi iwant2fly,

Firstly, these are really subtle differences – you wouldn’t be able to tell, we can only detect the changes with VERY sensitive instruments. Gravity is caused by mass. So in some places the earth is slightly heavier (perhaps there is a lot of metal ore under the ground), so it will have a stronger gravity.

This is actually a really important way that mining companies search for new areas to mine. They’ll fly over a new area in a plane with a gravitometer on board. If they fly over an ore body, which are usually heavier than the surrounding rock, then the gravitometer will show a small increase. They then know that that’s a good place to go and explore next.