Conversely, the moons gravity affects the largest bodies of water on earth but yet nothing else.
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The north pole of a magnet will attract the south pole of another magnet, and every magnet has both a north and south pole.
Your compass has a little magnetised needle that’s very carefully balanced – and the north pole of your compass needle is pulled towards the “south” pole of the earth’s magnetic field, which is located geographically near a place we call the “North pole”.
[Yes, it’s confusing, but we’re stuck with these terms: the earth’s “North Magnetic Pole” is actually a magnetic “south pole”. The north pole of a magnet is the one attracted to earth’s “Nouth pole”, and opposite poles attract.]
So that’s why your compass swings, but why can’t the earth’s “magnet” pick up paper clips?
When you bring a paper clip near a magnet, it gets slightly (temporarily) magnetised. It has a temporary north and south pole. The north pole will be pulled towards the other magnet’s south pole, and the paper clip’s temporary south pole will be pulled towards the magnet’s north pole. Typically, one of those forces is stronger than the other, because of the geometry of the situation – one of the magnet’s poles is closer to the paper clip, for example. You’ll notice that a paper clip attached to a strong magnet will sometimes “stand up”, because the opposite pole is *repelled* by the magnet, but not strongly enough that it can pull the paper clip off the magnet.
The earth’s magnetic field is, at any particular place, pretty uniform. The temporary north and south poles of the paper clip will be equally pulled and pushed away from and towards the earth’s poles. Therefore there’s almost no net magnetic force acting on the paper clip, and it stays safely in your stationary drawer until the day before you want to use it.
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