how does a compass know North?

Answer 1

There's a pretty good answer in 'Ask a Scientist'. I've copied it here for you.

A compass needle is a magnet (a weak one), and it tends to line up in such a way as to point its "north pole" towards the
North Pole of the planet. Why? Because the Earth is also a
magnet! It's filled with a dense iron core and so it gives off
a magnetic field. To investigate this, get two bar magnets,
and a compass. Notice that the compass points north. Now, take
one of the bar mangnets and slowly move it near the compass. You will see the compass needle "follow" the magnet. Since the bar magnet is close up, the needle "feels" the magnetism of the
bar more strongly than that of the Earth. Now, take the bar
magnet away and watch it point north again.

Put the compass aside and play with the two bar magnets. Notice that when you bring the two poles together which are the same ((N-N or S-S) you get a different result than if you bring them together N-S or S-N. Now, try laying one magnet on the table. Take the other magnet anduse it to "move" the first magnet the same way you moved the compass needle, by waving it nearby and using the magnetic force to move it without the two magnets actually touching each other (you need good, strong magnets - or light ones - to do this. Why?).

Hope this helps answer your question....the Earth is a giant magnet, (this is becauseof the molten iron core at the Earth's center) and thus it rotates light magnets to point at its north pole. -dr topper

Answer 2

There is a large mass of loadstone-- magnetic rock -- I think it's in Northern Canada-- formed as a result of the earth's magnetic field, and this is what pulls the needle -- This would make it the "magnetic north", but not the geographical north. It is a bit off-- the two don't match up. But unless you're charting the North POle, the difference it not usually an issue. The north (magnetic pole) fluctuates, but the geographic n. pole does not. ALSO, geologists believe that the Earth's core (mostly iron and nickel) is spinning more rapidly or at a different speed that the rest of the earth-- making an electromagnetic Dynamo-- and this is what makes the earth have a magnetic field to begin with.

honor roller-- you missed the point of the question

Answer 3

A compass is in the "river" of the earth's magnetic field, which extends from magnetic north to magnetic south.

The compass faces north because it is attracted to north.

Answer 4

many people think its a iron rock that is magnetic thats wrong if they are really smart they would know about the "van allen radiation belts".