Folks , the most striking statement from this article comes in the last paragraph - implying that jet streams on any planet are ultimately powered from the energy of their inner Sun , via their Polar openings . Strangely , wind speeds on Neptune , the coldest planet in our Solar System are the highest - touching an insane 1,500 miles per hour , that's 10 times faster than the jet streams on Earth , which receives good amount of heat from the Sun !
"The question still remains, however, of what powers the winds on these planets. Neptune in particular, has been a puzzle for a long time. It receives very little energy from the sun and has exceptionally cold (http://www.universetoday.com/21669/temperature-of-neptune/) surface layers, meaning that the powerful winds we see in its atmosphere may be driven by heat from inside the planet."
Neptune and Uranus Possess Weird Jet Streams
Uranus and Neptune have some of the strongest winds in the solar system, but those winds are confined to relatively thin layers of their atmospheres. Continue reading →
By Ian O'Neill
Published On 05/24/2013
2:19 PM EDT
The two planets in our solar system that we probably know the least about are the ice giants, Uranus and Neptune. Distant worlds that we've visited only once, courtesy of Voyager 2, what lies beneath their clouds is still very much a mystery. However, they both share one thing in common with Earth - the atmospheres of the two ice giants contain jet streams.
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The jet streams on Earth are high in the atmosphere. Powerful streams of wind flowing from East to West, at speeds of over 100 miles per hour (160 km/h). This may sound fast, but Neptune and Uranus aren't so gentle. Neptune is particularly turbulent, boasting the strongest winds in the entire solar system, reaching speeds of over 1,300 mph (2,100 km/h). But latest results show that those winds are only found in a relatively thin layer of these planets' atmospheres.
In a recent paper, lead author Yohai Kaspi and a group of researchers based in Israel and the US show that the viciously powerful winds in these worlds are confined to a relatively small region of their atmospheres, no more than 680 miles (1,100 km) deep.
Neptune and Uranus are twins in some respects. They're very close to one other in size, mass, and composition. They're also distinctly different to the two larger giant planets, Jupiter and Saturn, in that they contain more molecules like methane, ammonia, and water. While the larger gas giants are mostly hydrogen and helium, these light gasses make up only 20 percent of their colder sister worlds.
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Understanding the atmospheres of giant planets can tell us a great deal about how those planets work, but we still know very little about them. Only a handful of spacecraft have ever visited our solar system's largest worlds, and only one (the Galileo probe in 1995) has ever given us a glimpse of a giant planet, Jupiter, from inside its atmosphere. For a long time, a big question has been whether the winds reach deep into a planet's atmosphere, or if they're only found near the surface.
For this study, Kaspi and his colleagues used an ingenious trick. They analysed the gravitational fields of the two ice giant planets to look for how they were affected by winds. The gravitational field of any planet is affected by how dense it is.
In the case of a giant planet, the motion of the swirling winds is matched by a change in the planet's gravity. For the ice giants, results showed that just 0.15 percent of Uranus and 0.2 percent of Neptune were active, confining the weather on both worlds to a very thin layer.
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The question still remains, however, of what powers the winds on these planets. Neptune in particular, has been a puzzle for a long time. It receives very little energy from the sun and has exceptionally cold surface layers, meaning that the powerful winds we see in its atmosphere may be driven by heat from inside the planet.
We may be a long way from knowing exactly how giant planets work, but results like these put us a step closer to fully understanding what goes on inside worlds like these - both within our solar system, and elsewhere.
Image: Voyager 2 image of Neptune. Credit: NASA/JPL
Neptune Winds Hit 1,500 M.P.H. : Space: Data sent back by the Voyager craft reveals the unexpected currents, the fastestin the solar system.
By LEE DYE
Dec. 6, 1989
12 AM
TIMES SCIENCE WRITER
SAN FRANCISCO —
Scientists studying images sent back by the the Voyager spacecraft last August have discovered the fastest winds in the solar system whipping around Neptune at about 1,500 miles an hour.
The scientists found the unexpected winds after they plotted fleecy white clouds shown in a series of Voyager photographs. The clouds are being pushed at nearly supersonic speed on Neptune by winds that are similar to the jet stream on Earth, Caltech physicist Edward Stone said.
Stone, the chief scientist on the Voyager project, was one of several scientists who reported new findings during the fall meeting of the American Geophysical Union here.
Neptune and its rings and satellites continue to dazzle and baffle scientists, who are still trying to unscramble the enormous amount of data sent back by the intrepid spacecraft, which is now on its way out of the solar system.
Scientists, for instance, still have no explanation for why Neptune should have such fierce winds--nearly a third faster than the 1,100-m.p.h. jet stream on Saturn.
In the months since Voyager swept past Neptune, scientists have also confirmed the most spectacular discovery growing out of the August encounter: They thought they had detected something that looked like an ice volcano on Neptune’s strangest moon, Triton, but they were so unsure of what they were seeing that they described it as a “mad idea.”
Now, however, they are convinced that Triton does, indeed, have many ice volcanoes, and several were caught in the act of erupting when Voyager zipped past.
Multiple images that show the features from various angles have given scientists a stereoscopic view of Triton, and they clearly show that dark streaks coming from the volcanoes are like plumes of smoke drifting through the satellite’s thin atmosphere.
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The fact that Voyager captured pictures of so many volcanoes led Torrence Johnson of the Jet Propulsion Laboratory to conclude that “these things (ice volcanoes) apparently have lifetimes of several years.” If they were sudden, brief and isolated events, it would seem unlikely that so many would have been going off when Voyager happened by, he said.
That still leaves scientists without a full explanation for why the small moon should have ice volcanoes--something not seen anywhere else in the solar system.
Johnson speculated that the volcanoes may work something like this: Organic materials in the atmosphere are darkened through solar radiation, in a photochemical process similar to that on Earth. The materials fall to the ground, where they form a thin skin and become covered with nitrogen ice during Triton’s winter snowstorms. Then, solar radiation passes through the ice and heats the trapped material, which absorbs more radiation because it is dark. That causes the trapped material to expand and eventually explode through a weakness in the ice.
That mechanism is not too dissimilar from the “heat engine type of volcanoes” on Earth, Johnson said, although no one expected to find it on the frozen surface of Triton. While scientists seem to be increasingly comfortable with the idea of Triton’s ice volcanoes, they remain baffled by the thin rings that surround Neptune. The rings are irregular in that they have some sections that are so much fatter than others that scientists first thought Neptune had only partial rings, or ring arcs, when they were discovered with ground-based telescopes several years ago.
Voyager proved that the rings are complete, numbering either four or five, depending on who is doing the counting, but they are very irregular. Scientists could see no reason why the dust particles and rocks that make up the rings should not be distributed evenly around the planet.
Yet the rings clearly are “lumpy,” as one scientist put it, so scientists have spent the past few months searching Voyager images for small moons near the arcs. The leading theory explaining the arcs held that small moons could “shepherd” debris into the arcs, causing more material to accumulate in those areas.
But planetary scientist Jeff Cuzzi of NASA’s Ames Research Center in Mountain View, Calif., shot that theory down Tuesday on the basis of intensive examination of images sent back by Voyager.
“You have to have satellites at specific locations, but they’re not there,” Cuzzi said. “That (theory) didn’t work.”
No one has come up with an explanation yet that appears to work, he said.
“People are extremely puzzled,” Cuzzi added.
