They take 25 years to orbit Neptune at an average of times the distance between Earth and the Moon. It is likely that Neptune's inner satellites are not the original bodies that formed with Neptune but accreted rubble from the havoc that was wreaked after Triton's capture. Triton's original captured orbit would have been highly eccentric, and caused chaotic perturbations in the orbits of the original inner Neptunian satellites, caussing them to collide and become reduced to a rubble disc.
Only after Triton's orbit became circularised did some of the rubble disc re-accrete into the present-day satellites. In this scenario, Triton is the surviving member of a binary object1 disrupted by the encounter with Neptune.
Reference Terms. Neptune has 13 known moons. It took a hundred years to discover the second, Nereid. Triton, the largest satellite of Neptune, orbits in the opposite direction from most moons, suggesting that Neptune captured it in the distant past. Millions of years from now, Triton will move so close to Neptune that tidal forces will rip Triton apart, forming bright new rings around the giant planet.
Most of what we know about Triton came from Voyager 2, which photographed a landscape that is tinted subtle shades of pink, brown, and blue. Much of it resembles a cantaloupe, with ridges thousands of feet tall. Flowing ice or vaporizing gas may have carved this wrinkly terrain. Full Moon Guide: October - November The rover will be delivered to the Moon's surface in late VIPER is the first resource-mapping mission on the surface of another celestial body.
Full Moon Guide: September - October For the first time, astronomers have uncovered evidence of water vapor in the atmosphere of Jupiter's moon Ganymede. A technique for scanning Mars rocks for microscopic fossils is also being developed to hunt for microbes on Enceladus, Titan, and Europa. Phobos orbits through a stream of charged atoms and molecules that flow off the atmosphere of Mars, new research shows. Astronomers using Hubble watched a mysterious dark vortex on Neptune abruptly steer away from a likely death on the giant blue planet.
Dark Storm on Neptune Reverses Direction. Plumes of water vapor that may be venting into space from Jupiter's moon Europa could come from within the icy crust itself, according to new research.
New experiments re-create the environment of Europa and find that the icy moon shines, even on its nightside. In , NASA sent two Voyager probes on a one-way trip through the outer solar system, taking advantage of a rare planetary alignment that allowed them to move from one location to the next without using a lot of fuel.
Voyager 2 flew by Neptune and its system on Aug. Among the spacecraft's most stunning finds: icy volcanism is likely taking place on Triton's surface. Voyager 2 took pictures of "several geyser-like volcanic vents that were apparently spewing nitrogen gas laced with extremely fine, dark particles," according to NASA. The agency estimates the particles go as high as 5 miles 8 kilometers before flowing downwind and striking the surface. It also appears that a large portion of the surface has melted.
NASA said the melting was probably due to tidal heating that began when Neptune captured Triton, which could have left the satellite liquid for at least 1 billion years. Although no spacecraft will go by Neptune's system in the near future, computer models and higher-resolution telescopes on Earth are providing new information about Triton's history and environment. In , long-range infrared observations with the European Southern Observatory's Very Large Telescope revealed that the thin atmosphere of Triton changes with the seasons.
At the time the VLT looked at the planet, it was summer in the southern hemisphere, where the sun's warmth thickened the atmosphere. New models of Neptune could also provide insights on Triton, such as one released in that looks at the gas giant's magnetosphere. The magnetic field appears to be particularly pronounced on one side , according to Voyager 2 data and the model, and scientists next want to figure out how this field could interact with Triton.
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