Is there a way that I can point to a spot on the earth and know the exact opposite side to it?

Question

For instance if I was to point to a particular place in Australia, how can I tell where the exact opposite place is in the world. IE if you were to dig a straight hole through from that place, where you would end up?

(please dont say get a globe and measure halfway round. Im looking for something a little more scientific than that lol )

Answer 1

Determine the latitude and longitude. Take Sydney for example 33.9°S 151.2°E (close enough). Change the Latitude from S to N and add 180° to the longitude.

This gives you 33.9°N 28.8°W. This point is the antipodes of Sydney. Look it up on a map and you will find it is near the Azores in the Atlantic off the coast of north Africa.