You can see the effect of Earth’s magnetic field when you hold a compass in your hand— the needle points north, and knowing which way is north can help you find south, east, and west. Some animals can figure this out without looking at a compass. They have tiny bits of metal in their cells that act like tiny compass needles! These bits of metal rotate to point north, giving these animals a natural sense of which way is north. Animals like bees, bats, and some types of birds use this knowledge to find their way. Some use it for short distances, like bees that have flown away from their hives. Others, like snow geese, use it to migrate thousands of miles every year.
Earth acts like a giant bar magnet, with a north pole and a south pole that affect compass needles, but there isn’t actually a bar magnet in the center of Earth. Earth’s magnetic field is caused by the planet’s liquid iron core moving around. The process that creates a planet- wide magnetic field is called geomagnetism.