Voyager 2 sending back eerie' music of the spheres'
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"Jupiter was quite familiar," explains Dr. Scarf, recalling what his instrument on the Voyager spacecraft found when it flew by Jupiter two years ago. The main difference was that Jupiter is much, much bigger than Earth and so was its magnetic envelope.Skip to next paragraph
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A planet's magnetic field creates this music by its effect on electrically charged particles. These oscillate in a magnetic field in a similar fashion to a guitar string vibrating when plucked. The electrons are the lightest particles so they make the highest-pitch sounds. Protons are the tenors in the celestial chorus while heavier ions are the bases.
Of all the magnetospheres he has encountered, Dr. Scarf considers Saturn's the strangest and most mysterious. Saturn actually "rings" at certain, piercing tones. Sometimes these persist for long times. At others they turn off and on frequently.
According to Dr. Scarf's fellow experimenter, Don A. Gurnett of the Iowa State University, there is some evidence that this may be one of Saturn's moons "singing" to its parent planet.
Also, their radio ears have picked up wild chirps, whistles, and moans unlike any other planet. These are thought to be related to the physical rings. The rings are thought to carve out a big void from the center of the magnetosphere and this acts as a whispering gallery.
Saturn's music also differs substantially from that of Earth and Jupiter, the scientist reports. It is slow and deep, like a quartet of giant bass fiddles, he says.
The synthesized version of the Voyager 1 spacecraft flying past Saturn's planet-sized moon, Titan, is perhaps the most dramatic piece of celestial music that the scientist has. Deep, throbbing tones build in intensify to an almost unbearable level until, a little like Ravel's Bolero, the sound abruptly cuts off, followed by almost total silence.
Less musical, perhaps, but definitely peculiar, is the fact that Saturn itself gives off regular bursts of radio static in addition to its magnetosphere.
Jupiter and Earth both exhibit similar radio outbursts, but both of these planet's have a magnetic field that is oriented at an angle to their axis of rotation. This causes their magnetic field to focus high-energy particles on specific spots in their upper atmosphere, a process that gives rise to the radio noise.
On Saturn, however, the magnetic field has appeared to coincide with the planet's spin axis, making it difficult to explain why only a specific spot would generate radio frequencies when it rotated into the Sun.
Now, Voyager scientists believes they have found a very slight tilt to the magnetic field. It is only one-twelfth that of Earth's, but it might be enough to explain the radio bursts. According to Dr. Norman Ness of NASA's Goddard Space Flight Center, more work is required to pin down the direction of this tilt relative to the active radio region. But if Saturn's radio turns on when the magnetic field "nods" in the direction of the Sun, then the radio bursts will be explained.
Now dr. Scarf and his fellow scientists must wait five years until the spacecraft reaches Uranus. Then they will try to record the voice of this even more-distant world. In the meantime, he intends to try to synthesize the sounds of Venus.The US has a satellite in orbit around Venus and he will try to make some music out of the radio signals this probe encounters as it orbits Earth's veiled twin.