The planets of the outer system are known for being strange, as are their many moons. this is often very true of Triton, Neptune’s largest moon. additionally to being the 7th largest moon in solar system , it’s also the only major moon that features a retrograde orbit – i.e. it revolves in direction opposite to the planet’s rotation. this means that Triton didn’t form in orbit around Neptune, but may be a cosmic visitor that gone by at some point & decided to remain .
And like most moons in outer system , Triton is believed to be composed of an icy surface & a rocky core. But unlike most Solar moons, Triton is one among the few that’s known to be geologically active. This leads to cryovolcanism, where geysers periodically break through the crust & switch the surface Triton into what’s bound to be a psychedelic experience!
Discovery and Naming:
Triton was discovered by British astronomer William Lasseli on October 10th, 1846, just 17 days after the invention of Neptune by German astronomer Johann Gottfried Galle. After learning about the invention , John Herschel-the son of famed English astronomer William Herschel, who discovered many of Saturn & Uranus’ moons – wrote to Lassell & recommended he observe Neptune to ascertain if it had any moons also .
Lassell did so and discovered Neptune’s largest moon 8 days later. 34 years later, French astronomer Camille Flammarion named the moon Triton – after the Greek sea god & son of Poseidon– in his 1880 book Astronomie Populaire. it might be several decades before the name caught on however. Until the invention of the 2nd moon Nereid in 1949, Triton was commonly known simply as “the satellite of Neptune”.
Size, Mass and Orbit:
At 2.14 × 1022 kg, and with a diameter of approx. 2,700 kilometers (1,680 miles) km, Triton is that the largest moon within the Neptunian system – comprising quite 99.5% of all the mass known to orbit the earth . additionally to being the 7th largest moon in solar system, it’s also more massive than all known moons in solar system smaller than itself combined.
With no axial tilt & an eccentricity of virtually zero, the moon orbits Neptune at a distance of 354,760 km (220,438 miles). At this distance, Triton is that the farthest satellite of Neptune, & orbits planet every 5.87685 Earth days. Unlike other moons of its size, Triton features a retrograde orbit around its host planet.
Most of the outer irregular moons of Jupiter & Saturn have retrograde orbits, as do a number of Uranus’s outer moons. However, these moons are all far more distant from their primaries, and are rather small as compared . Triton also features a synchronous orbit with Neptune, which suggests it keeps one face aimed towards the planet at all times.
As Neptune orbits the Sun, Triton’s polar regions alternate facing the Sun, leading to seasonal changes as 1 pole, then the opposite , moves into the sun light . Such changes were observed in April of 2010 by astronomers using the European Southern Observatory’s Very Large Telescope.
Another all-important aspect of Triton’s orbit is that it’s decaying. Scientists estimate that in approximately 3.6 billion years, it’ll pass below Neptune’s Roche limit and can be torn apart.
Composition:
Triton features a radius, density (2.061 g/cm3), temperature & chemical composition almost like that of Pluto. due to this, & therefore the incontrovertible fact that it circles Neptune during a retrograde orbit, astronomers believe that the moon originated in Kuiper Belt and later became trapped by Neptune’s gravity.
Another theory has it that Triton was once a dwarf planet with a companion. during this scenario, Neptune captured Triton & flung its companion away when the enormous gas moved further out into the system, billions of years ago.
Also like Pluto, 55% of Triton’s surface is roofed with frozen nitrogen, with water ice comprising 15–35% and solid (aka. frozen carbon dioxide) forming the remaining 10–20%. Trace amounts of methane & carbon monoxide gas ice are believed to exist there also , as are small amounts of ammonia.
Triton’s density suggests that its interior is differentiated between a solid core made from rocky material & metals, a mantle composed of ice, and a crust. there’s enough rock in Triton’s interior for decay to power convection in mantle, which can even be sufficient to take care of a subterranean ocean. like Jupiter’s moon of Europa, the proposed existence of this warm-water ocean could mean the presence of life beneath the icy crusts.
Atmosphere and Surface Features:
Triton features a considerably high albedo, reflecting 60–95% of the sun light that reaches it. The surface also quite young, which is a sign of the possible existence of an interior ocean & geological activity. The moon features a reddish tint, which is perhaps the results of the methane ice turning to carbon thanks to exposure to ultraviolet .
Triton is taken into account to be one among the coldest places within the system . The moon’s surface temperature is approx. -235°C while Pluto averages about -229°C. Scientists say that Pluto may drop as low as -240°C at the furthest point from the Sun in its orbit, but it also gets much warmer closer to the Sun, giving it a better overall temperature average.
It is also one among the few moons in solar system that’s geologically active, which suggests that its surface is comparatively young thanks to resurfacing. This activity also leads to cryovolcanism, where water ammonia & nitrogen gas burst forth from the surface rather than liquid rock. These nitrogen geysers can send plumes of nitrogen 8 km above the surface of the moon.
Because of the geological activity constantly renewing the moon’s surface, there are only a few impact craters on Triton. Like Pluto, Triton has an environment that’s thought to possess resulted from the evaporation of ices from its surface. Like its surface ices, Triton’s tenuous atmosphere is formed from nitrogen with trace amounts of carbon monoxide gas & little amounts of methane near the surface.
This atmosphere consists of a troposphere rising to an altitude of 8km, where it then gives thanks to a thermosphere that reaches bent 950 km from the surface. The temperature of Triton’s upper atmosphere, at 95-100 K (ca.-175 °C/-283 °F) is above that at the surface, thanks to the influence of radiation & Neptune’s magnetosphere.
A haze permeates most of Triton’s troposphere, thought to be composed largely of hydrocarbons & nitriles created by the action of sunlight on methane. Triton’s atmosphere also has clouds of condensed nitrogen that lie between 1-3 km from the surface.
Observations taken from Earth & by the Voyager 2 spacecraft have shown that Triton experiences a warm summer season every few 100 years. this might be the results of a periodic change within the planet’s albedo (i.e. its gets darker & redder) which might be caused by either frost patterns or geological activity.
This change would allow more heat to be absorbed, followed by a rise in sublimation & atmospheric air pressure . Data collected between 1987 & 1999 indicated that Triton was approaching one among these warm summers.
Exploration:
When NASA’s Voyager 2 made a flyby of Neptune in August of 1989, the mission controllers also decided to conduct a flyby of Triton – almost like Voyager 1‘s encounter with Saturn & Titan. When it made its flyby, most of the hemisphere was darkly and unseen by Voyager.
Because of the speed of Voyager’s visit and therefore the slow rotation of Triton, just one hemisphere was seen clearly at close distance. the remain of the surface was either darkly or seen as blurry markings. Nevertheless, the Voyager 2 spacecraft managed to capture several images of the moon & spotted geysers of nitrogen blasting out of 2 distinct features on the surface.
In August of 2014, in anticipation of New Horizons impending encounter with Pluto, NASA restored these photos and used them to make the 1st global color map of Triton. Produced by Paul Schenk, a scientist at the Lunar & Planetary Institute in Houston, the map was also wont to make a movie (shown below) that recreated the historic Voyager 2 encounter in time for the 25th anniversary of the event.
Yes, Triton is indeed an unusual moon. apart from its rather unique characteristics (retrograde motion, geological activity) the moon’s landscape is probably going to be a tremendous sight. For anyone standing on the surface, surrounded by colorful ices, plumes of nitrogen & ammonia, a nitrogen haze & Neptune’s Big Blue disc hanging on the sky, the experience would appear like something like a hallucination.
In the end, it’s regrettable that the solar system will 1 day saying good-bye to the present moon. due to the character of its orbit, the moon will eventually fall under Neptune’s gravity well and break . At which point, Neptune will have an enormous ring like Saturn, until those particles crash into the planet also .
Homewrecker
Neptune’s original family of satellites may are destroyed when its largest moon, Triton, entered the image. New research suggests that the huge moon may have tossed a number of the original satellites into the ice giant, kicked others out of orbit & swallowed up the remain, creating a newn family that does not look very similar to those surrounding the opposite giant planets.
For years, scientists have suspected that Triton wasn’t a part of Neptune’s original collection of moons. the huge moon features a backward orbit, and makes up over 99% of all the mass orbiting the planet. Instead, they thought it had been a captured object whose orbit was circularized by debris disks created by impacts.
New research suggests that the crashing primordial moons wouldn’t have built up enough material to hamper or slow down Triton.
“We find that the mutual impacts between satellites aren’t disruptive enough to make the specified debris disk,” Raluca Rufu, a doctoral student at the Weizmann Institute of Science in Israel, told Space.com by email. Working with co-author Robin Canup, a researcher and associate vice chairman at the Southwest Research Institute in Colorado who models solar-system evolution & collisions, Rufu is lead author on new research that means Triton likely sent Neptune’s original satellites flying.
The moons of Jupiter, Saturn & Uranus are all well-behaved compared with those of Neptune. Other 3 gas giants have a wealth of satellites — Jupiter has 70 to Neptune’s 14, as an example — traveling in nearly circular paths around their equators. While Triton’s path is circular, it travels backward compared with Neptune’s rotation, & spins backward, besides.
And Triton isn’t the sole outlier at Neptune. Nereid, one among the planet’s outermost moons and therefore the 3rd largest, has one among the foremost stretched , or eccentric, orbits of any moon in our solar-system . It takes 360 Earth-days for the small moon to form one loop around its planet.
The unusual combination of moons led scientists to suggest that Triton was a part of a pair of objects from edge of solar-system that burst into the Neptunian system.
“The leading theory of Triton’s capture is that Triton was a part of a binary numeration system , almost like Pluto & Charon,” Rufu said. “Triton was captured while the secondary body escaped Neptune’s gravitational pull.”
Rufu & Canup modeled a Neptunian family almost like other gas giants, then had Triton crash the party. Over time, the extended orbit of a captured satellite should settle into the more circular orbit seen today, through interactions with other moons and little objects.
Previous studies had shown that Triton’s irregular orbit needed to calm down within 100 thousand years, or irregular satellites like Nereid would are tossed out, the researchers said. Rufu & Canup found it had been n’t enough for Triton to only hit the tiny satellites after it was captured—it had to throw a number of the moons out, as well.
Instead of modeling an intruder that settled in smoothly with its new family, they crashed Triton into other, smaller satellites, sending many of them flying. The energy from the impacts knocked the rough edges off Triton’s orbit, allowing it to succumb to Neptune’s gravitational tugs and become more circular.
While a number of the orignal satellites were hurled into space or swallowed up by Neptune, others may are absorbed by Triton itself.
“If we would like to seem for the primordial Neptunian satellites, my best guess would be to seem inside Triton,” Rufu said. She warned that the energetic impacts could melt the satellites, removing any observable craters & making the primordial pieces tougher to spot .
It’s regrettable for Neptune’s original satellites that the ice giant didn’t start out with more moons. Rufu & Canup found that a more massive primordial family could have meant doom for Triton. As long because the mass of original satellite system was like Uranus, which has only 27 moons, Triton would dominate, wreaking havoc as a homewrecker. But if the system had contained a more massive moon, Triton might not have stood an opportunity . consistent with Rufu, a collision with an outsized enough satellite during a prograde orbit, along same path because the planet’s rotation, would have thrown Triton into Neptune.
“A massive prograde moon decrease Triton’s speed an excessive amount of , and cause Triton’s fall,” Rufu said.
