The Planet Jupiter:

How To Hear Radio Signals From Jupiter





Jupiter is a source of powerful bursts of natural radio waves that can produce exotic sounds when picked up on Earth using simple antennas and shortwave receivers.



Even though human ears can't hear the radio waves directly, they make an exciting listening experience when converted to audio signals by a receiver.



It's not E.T. phoning home. The shortwave radio signals from Jupiter aren't a sign of extraterrestrial intelligence. The emissions are generated naturally by plasma instabilities in Jupiter's magnetosphere.



Pulsing power beam. Most space physicists say that ionized gas in the upper atmosphere above Jupiter's magnetic poles sometimes behaves like a powerful radio laser or maser. The radiation can be so intense that Jupiter frequently outshines the Sun as a source of radio energy at ham radio wavelengths.



Where does the radio laser get so much power? It starts on Jupiter's volcanic moon Io.

RADIO IMAGE OF JUPITER





Tidal forces from Jupiter and its other large satellites superheat the interior of the moon Io and make it the most volcanic body in the Solar System.



Volcanic materials are thrown far above Io's surface. Much of that enters orbit around Jupiter, forming a huge gaseous donut around the giant planet.



With a diameter the size of Io's orbit, the electrically conducting "Io torus," as it's known, spans 525,000 miles and has an important impact on Jupiter's magnetic environment.



Two trillion watts. As Io's orbital motion carries it through this magnetized ring of ionized gas, a huge electrical current flows between Io and Jupiter. Carrying about two trillion watts of power, it's the biggest DC electrical circuit in the Solar System.



Unlike the ordinary kind of DC circuit we know using batteries and wires, plasma physicists believe that current in the Io-Jupiter system is carried by a type of magnetic plasma wave called Alfven waves.



However it works, this awesome current is the power source for plasma waves that give rise to the laser radio signals that travel away from Jupiter's magnetic poles in cone-shaped beams.



The beams rotate with the giant planet every 9 hours and 55 minutes making Jupiter something like a slow-turning pulsar. When the beams sweep past our planet Earth, listeners here can pick up the Jovian radio bursts in the shortwave bands between 15 and 40 MHz.





RADIO IMAGE OF JUPITER The radio images of Jupiter on this page were recorded by the Australia Telescope National Facility (ATNF) of the Commonwealth Scientific and Industrial Research Organisation (CISRO). The Australia Telescope is a set of eight radio-receiving dish antennas at three sites in New South Wales. It is the largest single astronomical institution in Australia. The image at the top of this page was received by ATNF at a wavelength of 22cm. The image immediately above was received by ATNF at a wavelength of 13cm. By comparison, the amateur Radio JOVE telescopes observe Jupiter at wavelengths near 1500 cm.

Radio JOVE.

How sensitive is it?

What does it sound like?

Through the loudspeaker of a shortwave receiver, the so-called "L-burst" sounds like ocean waves crashing on a distant beach. The "L" stands for long. If a recording is slowed down dramatically, the S-burst sound like eerie drifting whistlers.





Through the loudspeaker of a shortwave receiver, the so-called "S-burst" produces a staccato of rapid popping sound with a beat that reminds some of woodpeckers. The "S" stands for short.

Sample Sounds.

Student Observing Party.

What if you can't build one?

The Sun also shines.

Bonus Audio.

Learn more about Jupiter and radioastronomy