From its surface and construction, to its uniqueness in regards to moons, and more!
Join us as we reveal to you Triton: Neptune's weird moon facts and history!
6.
Discovery and Naming When it comes to the discovery of planets
and moons, many have their own unique stories and histories of being found, and Triton is
no exception to that.
Triton was discovered by British astronomer William Lassell in 1846.
Which is important because it was found just 17 days after the discovery of Neptune.
Which is odd when you consider that many other moons were found long after their planets
had been discovered, and some were even convinced that they weren't moons at first.
But that's another story for another time.
But the story is more layered than you may expect.
This all started when John Herschel heard of Neptune's discovery, interested in what
this could all mean he went to Lassell and suggested that he look for moons that might
be around the planet.
Lassell did so and discovered Triton eight days later.
Which is interesting because he honestly wasn't an astronomer, but a brewer, and Lassell spotted
Triton with a aperture metal mirror reflecting telescope that he built on his own.
This telescope was later donated to the Royal Observatory, Greenwich in the 1880s, but was
eventually dismantled.
This is still an amazing thing, because you usually hear of the legends using very special
telescopes to find moons and planets, but Lassell just built his own and looked to the
stars.
If only everything was so simple.
As for the naming of the moon, Triton is named after the Greek sea god Triton, the son of
Poseidon who happens to be one of the main Greek gods.
The name was first proposed by Camille Flammarion in a book and was officially adopted many
decades later.
5.
Orbits and Rotations Triton is unique among all large moons in
the Solar System for its retrograde orbit around its planet (i.e. it orbits in a direction
opposite to the planet's rotation).
Certain moons of Jupiter and Saturn also have these kinds of orbits, as do some of Uranus's
moons.
The difference though is that these moons are all much more distant and are small in
comparison; the largest of them (Phoebe) has only 8% of the diameter of Triton.
So for Triton to do this is very odd indeed, which has gotten the attention of many as
they try and understand why exactly this moon has such an odd orbit.
Triton's orbit precesses forward relative to Neptune's spin with a period of about 678
Earth years making its Neptune-orbit-relative inclination vary between 127° and 180°.
That inclination is currently 130°; Triton's orbit is now near its maximum departure from
coplanarity with Neptune's.
Triton's rotation is tidally locked to the extent that as it goes around Neptune it'll
always keep one face oriented toward the planet at all times.
In fact its equator is near perfectly aligned with its orbital plane.
Triton's rotational axis is about 40° from Neptune's orbital plane, and hence at some
point during Neptune's year each pole points fairly close to the Sun, which is similar
to its sister planet of Uranus.
As Neptune orbits the Sun, Triton's polar regions shift in looking at the Sun, resulting
in seasonal changes as one pole shifts towards the sunlight.
In 2010, these were seen by us here on Earth, kind of making it a rare sight.
Triton's revolution around Neptune has become a nearly perfect circle, which is not something
you'd expect to hear.
But how exactly the moon was able to do that is a bit unknown.
There are many factors that play into this and scientists aren't sure how many worked
towards this achievement.
Though certain gasses possibly slowing down the moon during its origin period to obtain
this is likely.
Another thing to note about Triton's orbit is that it is already closer to Neptune than
the Moon's is to Earth.
Which absolutely is something to make note of, because predictions are that 3.6 billion
years from now, Triton will pass within Neptune's Roche limit.
This will result in either a collision with Neptune's atmosphere or the breakup of Triton,
which in turn will form a ring about Neptune at some point in time.
Which is something that would truly be something magnificent to witness firsthand.
Though it's doubtful that humanity will be around to witness it.
This isn't the only moon in the solar system to have this eventual fate, but to have it
happen with such a large moon is special indeed.
Though again it will not happen for billions of years.
And there's another factor in regards to a moon with a retrograde orbit like this that
must be taken into account.
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4.
Its "Capture" Moons in retrograde orbits cannot form in
the same region of the solar nebula as the planets they orbit, so Triton must have been
captured from elsewhere.
For those confused, the Solar Nebula is the dominant theory of how the solar system was
made.
Gas and debris from the Big Bang eventually formed the sun, and the gravity of the sun
eventually formed the planets, moons, and more.
In regards to Triton, the Kuiper belt, a ring of small icy objects extending from just inside
the orbit of Neptune to about 50 AU from the Sun is more than likely where it came from.
Which isn't too much of a stretch when you think about it considering all the other objects
that are known to come from there, and to have possibly come from there.
Including Pluto and other well-known objects.
Triton is only slightly larger than Pluto and nearly identical in composition, thus
making many believe that they are indeed from the belt, or at the very least close in regards
to how they formed.
Even though only one of them was ever considered to be a planet...and should still be considered
one.
Regardless of that though, understanding the "capture" of Triton may explain several features
of the Neptunian system as a whole.
Such as the eccentric orbit of Neptune's moon Nereid and the scarcity of moons it has compared
to the other giant planets.
Triton's presence may have even led to other moons being dispersed among the stars instead
of being captured by Neptune.
There are two major theories or beliefs as to how Triton's capture might have happened.
To be gravitationally captured by a planet, sufficient energy must be lost to be slowed
down to a speed so that it won't be able to escape the gravity of the planet.
An early theory of how Triton may have been slowed was by collision with another object.
Given the randomness of space, and the fact that other moons and planets have been pelted
by rocks of various sizes over the years, this is incredibly possible.
Though what exactly would have struck Triton is unknown.
Another idea though is that Triton was part of a binary system.
When this binary encountered Neptune, it interacted in such a way that the binary broke up, leaving
Triton with Neptune while the other half was sent away.
Most think that this could be what really happened because it's felt that Mars had a
similar thing happen with its two moons and their capture.
Binaries being very common among the large Kuiper belt objects, this could be what happened.
Some even saying that these kinds of events are "common" in regards to Neptune and its
formation.
But don't go thinking that this is the end, because simulations in 2017 showed that after
Triton's capture might have indeed been caused by several collisions of certain kinds.
You might find it interesting that we honestly don't know exactly how Neptune captured Triton,
but in fact, this is but one thing that we don't know about our solar system as a whole.
There have been many questions about its formation including the timing of formations of planets
like Mars, how the Earth got its moon and more.
And it's another key reason why astronomers and scientists continue to study the solar
system so that they can get answers to these questions.
3.
Characteristics of Triton Triton is the seventh-largest moon and sixteenth-largest
object in the Solar System, which is notable for various reasons, including how we look
at the solar system as a whole It comprises more than 99.5% of all the mass known to orbit
Neptune, including the planet's rings and thirteen other known moons, and is also more
massive than all known moons in the Solar System smaller than itself combined.
Which is again very important when you consider how we look at the solar system and gauge
things like these other moons.
Now, as for Triton's surface, it's covered with frozen nitrogen.
Only 40% of Triton's surface has been observed and studied though to be clear.
However, based on what we know it's likely that this frozen nitrogen does cover the whole
planet.
Triton's crust consists of 55% nitrogen ice with other ices mixed in.
Water ice comprises 15–35% and frozen carbon dioxide (dry ice) the remaining 10–20%.
Trace ices include 0.1% methane and 0.05% carbon monoxide.
Just as important, there might be ammonia ice on the surface, as there are indications
of ammonia dihydrate in the lithosphere.
Triton's mean density implies that it probably consists of about 30–45% water ice with
the remainder being rocky material.
An interesting balance to be sure.
What might surprise you though is that this moon has an unusually high albedo, reflecting
60–95% of the sunlight that reaches it.
By comparison, the Moon reflects only 11%.
This in turn helps explain its low temperatures and why it shines so brightly.
Models of the interior of the planet tell an interesting story, mainly in that the moon
might not be too different from how Earth is constructed as it has a solid core, a mantle
and a crust.
Potentially at least.
Water comprises Triton's mantle, enveloping a core of rock and metal.
There is enough rock in Triton's interior for radioactive decay to maintain a liquid
subsurface ocean to this day.
Which would make it a very unique moon, and something that MANY want to test out for themselves.
2.
Atmosphere Triton is one of a set of moons that honestly
does have an atmosphere around it.
But just because it does have one doesn't mean that it's one that can be likened to
Earth.
Triton has a nitrogen atmosphere, with trace amounts of carbon monoxide and small amounts
of methane near its surface.
Again, very different from Earth as we have ours.
Its surface temperature is at least 35.6 K (−237.6 °C), this is due in large part
because of Triton's nitrogen ice.
An upper limit in the low 40s (K) can be set from vapor pressure equilibrium with nitrogen
gas in Triton's atmosphere.
This also means that Triton is colder than Pluto via these processes.
Triton's surface atmospheric pressure is only about 1.4–1.9 Pa.
Turbulence at Triton's surface creates a troposphere rising to an altitude of 8 km.
Streaks on Triton's surface left by geyser plumes suggest that the troposphere is driven
by seasonal winds that are able to move more than you might expect.
However, Triton's lacks a stratosphere, and instead has a thermosphere from altitudes
of 8 to 950 km, and an exosphere above that.
The temperature of Triton's upper atmosphere is higher than that at its surface, due to
heat absorbed from solar radiation and Neptune's magnetosphere.
1.
Cryovolcanism Triton is not just a regular moon, rather,
it's a moon that has activity upon it via volcanoes.
Not the ones you think about when you hear the word, but ones with water and ammonia
as opposed to liquid rock.
Which makes them Cryvolcanoes, and not the kind we have here on Earth which shoot smoke
and lava.
Part of the reason that this is able to be like it is is due to the valleys and ridges
that Triton has over its entire surface.
These features on Triton are endogenic—the result of internal geological processes rather
than external processes such as impacts.
Two large cryolava lakes on Triton, seen west of Leviathan Patera.
Combined, they are nearly the size of Kraken Mare on Titan.
Which is obviously quite large and Titan itself has many interesting features like Triton
that make it unique.
One of the largest cryovolcanic features found on Triton is Leviathan Patera which is roughly
100 km in diameter and is so large it can be visible at the equator.
Around it is a volcanic dome that stretches for roughly 2000 km along its longest axis,
making it the second largest volcano in the solar system by area, after Alba Mons.
Which is rather impressive and something that many want to study.
The Voyager 2 probe (which has revealed all sorts of things across planets and moons)
observed in 1989 a handful of geyser-like eruptions of nitrogen gas and dust from beneath
the surface of Triton in plumes.
But not just small ones, ones that can reach 8 km into the air!
This means that Triton is one of the few bodies in the Solar System on which active eruptions
of some sort have been observed.
More studying of these could lead to even more revelations about Triton, which could
make it a place that is potentially landed upon by a rover or other device down the line.
And should they be able to, the study of these Cryovolcanoes could lead to interesting observations
of their own.
Thanks for watching!
What did you think of this look at Triton and everything that has to do with it?
Do you find Triton a bit more interesting of a moon now?
How do you think humanity will look at the moon going forward?
Let us know in the comments below, be sure to subscribe, and I'll see you next time on
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