Juno will reach Jupiter in just a few hours but it has already been producing fantastic science. One of the most fascinating pieces of data coming from the NASA probe so far is what the magnetic field of Jupiter sounds like.
The Waves instrument, which will study Jupiter’s auroras in detail, was taking recordings of the space environment around the giant planet when it recorded the haunting sounds of Jupiter’s bow shock on June 24.
The bow shock is the region where the supersonic solar wind, the stream of charged particles coming from the Sun, hits the Jovian magnetosphere. The particles in the solar wind move at about 400 kilometers per second (900,000 mph) and they are suddenly slowed down, like a rock diverts the flow of water.
About a day later Juno entered the magnetopause, the boundary between a planet’s own magnetosphere and the solar wind. There, it recorded the so-called “trapped continuum radiation”, which is generated by waves of particles pushed and pulled between Jupiter and the Sun.
Jupiter’s magnetosphere is the largest structure in the Solar System (excluding the heliosphere), and it is significantly stronger than the Sun’s magnetic field. It is formed by the intense electric currents within the planet’s core, which is made of metallic hydrogen, a rare state of matter that is only obtained at very high pressure.
Among many other scientific objectives, Juno will study in detail how the magnetic field changes around the giant planet, and unlock some of the secrets deep inside Jupiter after it arrives tonight.