In just four days, NASA’s Juno spacecraft will come in contact with one of the most treacherous forces in our solar system – Jupiter’s legendary magnetic field.

Scientists aren’t entirely sure why the Jovian magnetic field is so powerful. One theory states that, deep within Jupiter, a layer of metallic hydrogen is crunched to such a high pressure that it serves as a sort of electrical conductor. When combined with the planet’s quick rotation, that conductor generates the magnetism. Scientists do know, however, that the magnetic field fires particles — electrons, protons, and ions — out from its surface at almost the speed of light, creating the most extreme radiation environment in the solar system.

NASA’s new video, Exploring Jupiter’s Magnetic Field, attempts to explain in simple terms why Jupiter’s magnetic field remains a mystery and how the agency hopes to use Juno to uncover it.

Magnetic fields themselves are no great mystery. They’ve been studied extensively and, since the mid-20th century, dynamo action — the convective motion of an electrically conducting fluid — has been accepted as their cause. But, even though we can map Earth’s magnetic field, we can’t peer through our planet’s crust to witness the dynamo process in action.

Jupiter, however, is a different beast. The gas giant doesn’t have a solid crust, meaning that if Juno can get close enough, the spacecraft can actually take readings and images of the magnetic field at its source.

Jupiter is our solar system’s biggest, oldest, grumpiest planet. In response, Juno has been titanium-armored to withstand the planet’s offenses. For 37 consecutive flybys, the little spacecraft will get closer to Jupiter than any man-made object before it, using sophisticated observational equipment to gather as much data as possible and send it back to Earth before the planet overpowers it.