The sounds from Neptune are mysterious and alluring. At times they sound like strange drums and wind, at other times they resemble cricket sounds and thunderstorms. Like nothing you have ever experienced before from the farthest planet out in our solar system from which Voyager made sound recordings.
On its approach to Neptune in August 1989, Voyager 2 captured this image of the fourth and outermost of the giant gas planets. This image shows two of the four oval cloud features tracked by the cameras. The large dark oval near the left edge revolves around Neptune every 18 hours. The bright clouds immediately to the south and east of this oval substantially change their appearance in periods as short as 4 hours. The second dark spot, at the lower right edge, revolves around Neptune every 16 hours.
Voyager II swept past the Neptune system on August 24-25, 1989. Neptune's atmosphere proved surprisingly active, with wind velocities clocked at over 700 MPH. This dynamic climactic activity is powered by Neptune's internal heat, which provides over twice as much energy as the feeble sunlight that the planet receives. Neptune has eight moons and three rings, as well as a highly tilted and offset magnetic field.
Neptune's electromagnetic environment is surprising. It is inclined to the planetary axis by 47°. Periodic pulses of radio energy were also recorded, generated by rotation of the planet's deep interior. Neptune's lovely blue color is a result of methane, helium and hydrogen gasses in its atmosphere.
The picture of Neptune on the cover of this CD features the great dark spot, which is accompanied by white clouds that undergo rapid changes in appearance. To the south of the great dark spot is the bright feature that scientist's nicknamed "scooter". Still further to the south is the feature called "Dark Spot 2", which has a bright core.
For more information about plasma and magnetic fields and their relationship to our sound recordings from space, consult the April 1991 issue of Scientific American Magazine - article entitled "Collisionless Shock Waves".
Special thanks to our friends and contacts at various U.S National Space Agencies and Universities. This Space Recording Series is dedicated to the memory of Fred Scarf, PhD, who developed the acoustic recording project for Voyager and is directly responsible for the sounds you hear on these recordings from space.
Authentic photos made available courtesy of JPL and NASA