Useless tool: In space, where will a compass needle actually point?

On our planet, a compass can be utilized as a navigation tool, allowing humanity to successfully find the right path for hundreds of years while traveling across various corners of the Earth. Now, people have begun to explore space. But is this tool useful beyond Earth, and where will its needle point? This is discussed by Live Science.

According to Jared Esple from NASA's Goddard Space Flight Center, a compass in space will measure different things depending on where a person is located. Technically, the compass will still function in space, but it won't necessarily indicate the way back to Earth. Instead, the compass needle will point towards the north pole of whatever magnetic field is strongest relative to the person's position with the device.

On Earth, a compass responds to our planet's magnetic field and always points north. The Earth's global magnetic field is generated by electric currents flowing through the molten part of our planet's metallic core, which is constantly rotating. Earth is the only rocky planet with a strong magnetic field in the solar system.

The Earth's global magnetic field extends about 37,000 km on the side facing the Sun and about 370,000 km on the opposite side of the planet. The region around the planet influenced by the global magnetic field is called the magnetosphere. According to Esple, if an astronaut wanted to return to Earth using a compass, they would need to be within the magnetosphere. However, this may not necessarily happen.

When outside the Earth's magnetosphere, for example, on the surface of the Moon or Mars, which lack a strong magnetic field, a compass might detect weak signals from the magnetic field present in the cores of these worlds. In fact, it is likely that the compass needle in space would point towards Jupiter, which has an enormous magnetosphere measuring 21 million km wide.

If an astronaut finds themselves in deep space, where there is no influence from the magnetospheres of large planets, the compass will primarily measure the weak magnetic field of the solar wind. This wind creates the largest magnetosphere in the solar system, known as the heliosphere, which extends three times farther than Pluto (the average distance from the Sun is 5.5 billion km).

At the same time, the Sun's magnetic field is chaotic, with its north and south poles constantly switching places.

According to Esple, a traditional compass is actually quite useless in space as a navigation tool. It will not necessarily point to the Earth's magnetic field but rather to the magnetic field that is strongest at that location.