By tracing the movement of electrons towards Jupiter from its volcanic moon Io, researchers using NASA’s Juno spacecraft have discovered what is causing powerful radio emissions in the planet’s giant magnetic field.
The researchers explained that Jupiter has the largest and most powerful magnetic field among all the planets in our solar system, and the strength of its source is about 20 thousand times stronger than Earth. It is exposed to the solar wind – a stream of electrically charged particles and magnetic fields constantly emanating from the Sun.
Jupiter has several large moons that orbit within its massive magnetic field, Io being the closest of them. Its volcanoes collectively eject one ton of material per second into Jupiter’s space. Some of this material breaks down into electrically charged ions and electrons and is quickly captured by Jupiter’s magnetic field. As Jupiter’s magnetic field sweeps past Io, electrons from the moon are accelerated along the magnetic field towards Jupiter’s poles. Along the way, these electrons generate radio waves. Juno Waves can “listen” to this radio frequency and interpret it.
As it turns out, radio waves emanate from a source along the walls of a hollow cone aligned and controlled by the strength and shape of Jupiter’s magnetic field. Juno only receives a signal when Jupiter’s rotation engulfs this cone above the spacecraft.
Juno’s data allowed the team to calculate that the energy of the electrons generating radio waves is much higher than previously thought – about 23 times. Also, electrons don’t have to come from a volcanic moon. For example, they can be in the magnetic field of the planet (magnetosphere) or come from the Sun as part of the solar wind.