Triton, the Moon that was a Dwarf Planet!
Everyone knows that Triton is the largest moon of Neptune’s. But what if it wasn’t always like that?
What if I told you that Triton used to be a dwarf planet before?
Ever since its discovery, scientists have been really puzzled by this massive moon of Neptune.
Triton is really peculiar as it is covered by a thick layer of ice
that could even potentially be a host for life in the oceans underneath it!
A team of scientists at NASA claims that there’s a very big chance that Triton used to be a dwarf
planet before it was captured by Neptune, and turned into the very unique moon it is today. But
what made scientists suggest that possibility? How else could they
explain its peculiarities, like its weird orbital direction and high reflectivity?
Follow me in this video to get to unveil the incredible secrets of
this very distant world and get to know the answers to these questions and more!
Triton is the largest and most massive of Neptune's moons and is among the most
mysterious moons of our Solar System. It has a diameter of 2,706 kilometers, so in comparison
with our Earth’s Moon, Triton is just a little bit smaller, by around 800 km. Carrying a mass
of ten to the power of 22 kilograms, it is the seventh largest moon orbiting our Sun.
Neptune and its moon Triton have a very peculiar discovery story. It was observed two centuries
before it was discovered as a planet, that’s crazy right? Let’s take a little step back
in time into the discovery of Neptune. Once upon a time, in 1846, a new planet was
discovered, Neptune. The presence of it had been detected by Galileo Galilei very early in the year
1612, who used a primitive telescope to observe Jupiter and noticed a strange "point" near it.
This was later discovered to be Neptune, which had been in the same location during that time period.
The hunt to find it was on as astronomers noticed an issue with the orbit of Uranus
and hypothesized that an unknown world must be disturbing its orbital path.
Only 17 days after Neptune’s official discovery, Triton, its largest moon, was discovered by
William Lassell, an English astronomer. Fun fact: The moon was only given its
name a whole century later, until the discovery of the second moon of Neptune’s,
Nereid, in 1949. It was named after a Greek mythological merman, the son of the god Poseidon.
--- I mentioned dwarf planets before,
but do you know what makes them different from the planets we know? Let’s quickly define what a dwarf
planet is: The International Astronomical Union, which defines standards for planetary science,
states that a dwarf planet is an object that orbits the sun, is sufficiently massive to be
nearly round in shape, has not cleared the area around its orbit, and is not a moon.
So let’s go through all the reasons Triton is thought to be a former dwarf planet and
a new visitor to the Solar System rather than a moon formed around Neptune. Stay
attentive as this might blow your mind!
1) Retrograde motion In the past, people thought the universe
was like a big clock that worked the same way all the time. But now, we've found out that there are
a lot of things that don't work like that. For example, Uranus, which is tilted sideways, or
all of the comets and asteroids that travel around our solar system in many different directions. And
most intriguingly, Triton that orbits its planet Neptune in the opposite direction.
When Voyager 2 arrived at the Neptune system in 1989, it discovered Triton in a retrograde orbit.
Check out our video about Voyager 2, the only spacecraft to study all four of the Solar System’s
giant planets at close range! Link video:
https://www.youtube.com/watch?v=99m3XlO0cXQ
The moons of the outer solar system have earned a reputation for being strange, none more so than
Triton. As the seventh-largest moon in the solar system, it stands out for its retrograde orbit.
Retrograde motion is the phenomenon of a planet appearing to move backwards in the sky from our
vantage point on Earth. This occurs when the planet is orbiting at a more or less constant
speed, and is due to our unique point of view. In simpler words, imagine looking up at the sky
at night, you see different stars and planets in different parts of the sky every night. Sometimes,
one of the planets will seem to stop and suddenly go backward for a bit before going forward again.
That's called retrograde motion - it's like the planet is making a big loop in
the sky! This suggests that Triton was most probably not born in orbit around Neptune,
but instead could be a visitor from elsewhere in the universe that decided,
forcefully, to settle there around the planet. Scientists have been trying to figure out why
Triton travels in a weird way. Some people think it was because a long time ago something crashed
into it and changed the way it moves, but the numbers don't work out. If something
was that strong to change the way it moves, it would have smashed Triton apart instead.
Well, it is proposed that Triton, just like Pluto, was originally self-governing icy planetesimal
situated in the outer solar system. They both have similar dimensions, densities, and surface
compositions. Nevertheless, it is hypothesized that Neptune sort of kidnapped Triton early
on in its journey when Triton came too near to the colossal planet. It’s like if Triton used to be
friends with another planet, but got too close to Neptune who was very strong and grabbed it.
This slowed Triton down so that it could become friends with Neptune instead.
Without Neptune's help, Triton could have crashed into Neptune, or been sent away like a boomerang.
Scientists speculate that Triton's former partner has probably been thrown out of
the solar system due to its crossing with the outer planets, but the exact fate and current
whereabouts of the object remain uncertain. Scientists suggest that other planets may have
similarly captured moons, and astronomers have seen an increasing number of binary planetoids
in the asteroid and Kuiper belts. This type of binary-planet encounter that led to Triton's
capture is not particularly restrictive, and these kinds of objects have likely been around for
billions of years. Planetary scientists express enthusiasm for the computer model demonstrating
how binaries could have contributed to the growth of the moon population in the solar system.
The probability of Triton running into one system is tiny, and the model confirms the
high need for hundreds to thousands of Pluto-like dwarf planets, which is a thrilling discovery!
2) Unusually high albedo Triton stands out in the Solar
System for being one of the brightest objects in the sky. With an unusually high albedo,
which is the measure of how much light a surface reflects, Triton reflects 60 to 95% of the
sunlight that reaches it. By comparison, our Moon only reflects 11% of the light
that reaches it. This is quite remarkable, given its far distance from the Sun, and has remained
relatively unchanged since the first observations of it. Unlike other moons, Triton is most likely
composed of ices of nitrogen, methane, and carbon dioxide, making it appear unusually reflective.
This composition also suggests that Triton is a Kuiper belt object, much like Pluto
and other Trans-Neptunian Objects that have/may be have been captured by the planet's gravity.
The extraordinarily high albedo of Triton could help answer some long-standing questions about
how planets are formed. By studying the albedo of various moons and other planetary bodies,
scientists can gain better insight into the processes and forces that shape the Solar System.
For instance, it's thought that the relatively high albedo of Triton may be
the result of planetary formation processes that occurred in the outer solar system.
This high albedo has also made Triton an ideal candidate for study by planetary scientists.
Its high reflectivity means that it is much easier to observe and measure than other moons, making it
an ideal target for studying the Solar System. 3) Its surface composition and activity
Triton is believed to be made up of an icy surface and a rocky core,
similar to many moons of the outer Solar System. It stands out, however, in that it
is one of the few that are geologically active; this leads to the phenomena of cryovolcanism,
where geysers break through the surface and give a unique, psychedelic look to the moon.
It is possible that Triton's orbit may have been altered over time by gas drag, which can occur
when a moon passes through the atmosphere of its host planet. The close encounter with Neptune,
whether through a collision or through gas drag, would have caused Triton's orbit to become highly
eccentric. However, over time tidal interactions between Triton and Neptune caused the eccentricity
of the orbit to decrease, resulting in its current nearly circular orbit. It is estimated that over
a billion years passed from the moment Triton was captured until it reached its current,
circular orbit. In this time, the immense tidal forces Triton underwent would have caused it to
melt entirely. This molten material would have separated into two main parts: the
denser components sinking to the core of the moon and the lighter materials rising to the surface.
Triton's surface cooled faster than its core, forming a thick surface layer of mainly water ice.
As the water beneath the surface froze, it expanded, causing cracks on the external
ice layer. The Voyager images of Triton's fractured surface give testimony to the
presence of water ice in the moon, as no other component of its subsurface can expand upon
freezing. ---
In conclusion, the unusual orbit of Triton along with its unusual albedo and very circular orbit
provides insight into the dynamics of the outer Solar System and its interaction with Neptune.
Well, that's all you need to know about Triton's fascinating history. From its mysterious origin to
its retrograde orbit, Triton is a fascinating reminder that there is still so much left to
discover in our mysterious universe. We can only imagine what other secrets lie out there,
just waiting to be found, and we can only hope that scientists will soon unravel the
mysteries of our universe. Until then, sit back, relax, and enjoy the beauty of our Solar System!
You've reached the end of this video, if you have a theory on your own,
if Triton was indeed an independent planet before it was captured by Neptune, don't hesitate to let
us know in the comments! We are interested in what you think! Thank you for watching! See you later.