How does the compass tell us where the North Pole is when it's at the South Pole?

Imagine you are preparing for the journey of a lifetime: going to Antarctica. Here you will see Antarctica and can play with the penguins. But, how do you find the real South Pole?

You’ll probably think you need a compass at first. Compass – navigational tools containing magnetic pointers – have helped us humans find our way around the Earth for thousands of years of existence. The Earth’s magnetic field always draws one end of the magnetic pointer on the compass towards the North Pole, so the compass always tells us where north is.

However, you may not know that the compass does not work correctly when near the South Pole . Why is that?

How does the compass tell us where the North Pole is when it's at the South Pole?
Going to Antarctica, you can play with the penguins.

The Earth has both geographic and magnetic poles. The geographic positions of the North and South poles mark opposite ends of the central axis that the Earth will rotate. However, the position of the magnetic poles of the North – South ends is not fixed and the distance from the corresponding geographical poles can vary up to several thousand kilometers.

The Earth’s magnetic field is caused by the planet’s rotation and the irregular movement of the conductive liquid in the Earth’s core, so the magnetic field and the magnetic field poles, will change with speed. and fluid motion

The compass needles are designed to align with the Earth’s magnetic field. The north tip will point to the magnetic North Pole, while the opposite needle will point to the magnetic South Pole. When the compass is removed and the needles are stable, this axis will be parallel to the magnetic field line of the Earth where you are standing.

But the Earth’s magnetic field is not arranged in a straight line from the South Pole to the North Pole. As you approach the magnetic South Pole, the magnetic field lines will bend and go straight to the magnetic South Pole, perpendicular to the Earth’s surface. “So the compass will often not work,” said Tom Jordan, a geophysicist at the British Antarctic Survey. “Instead of trying to point horizontally, what the compass needle is really trying to do is point straight down to the Earth.”

That is to say, if you go to the South Pole and carry a compass with a three-dimensional free hand, the “south” tip of the compass will point straight down as soon as you reach the magnetic South Pole, Jordan confirmed. with Live Science.

At the magnetic North Pole, the compass will also suffer. The “north” needle will point straight into the ground, according to Jordan.

Because of this oddity of compasses near the North and South poles, Jordan explains, polar explorers calculated the position of north by mapping the angle of the sun or determining the position of the star. star . Today, everyone uses GPS to determine which direction is north in Antarctica. What they need to do is move around a bit to find the north, like when you don’t trust the information the map app on your phone tells us.

According to Jordan, a traditional compass will only provide the most accurate information about which is north and which is south when operating on the equator . That’s because at the equator, all of the planet’s lines of force are horizontal and parallel to the Earth’s surface.