Neptune it is the outermost planet from the Sun and the windiest in the solar
system. Stay with me in this video to learn everything there is to know about
Neptune. Let's start with its physical characteristics. Neptune gets
its name from the deep blue color of its surface, which is reminiscent of the sea
god Neptune. Neptune is a darkest, coldest and windiest place in the solar system,
making it one of the most inhospitable places to visit. The topmost clouds are
made of hydrogen, helium and methane, which whip around the planet at 2,000
kilometres per hour, faster than the speed of sound. Not only that but the
light that is received on earth is 900 times higher than on Neptune,
so noon on Neptune would appear as twilight. A feature seen on this image of
Neptune is the Great Dark Spot. This is a storm the size of Earth and is similar
to Jupiter's Great Red Spot. It is thought to be a gap in the methane
atmosphere, revealing the darker bands in the lower clouds.
However, this storm lasted only a few years as when photographed again by the
Hubble Space Telescope five years after Voyager 2's photo, the
spot was gone. However, these storms are quite frequent
on Neptune's surface and it spends more than half its time with one. Neptune is a
very similar size to Uranus at 49,244
kilometers wide but is denser at 1.64 grams per centimeter
cubed. This gives the planet the second largest
surface gravity in the solar system of 11.15 meters per second squared, and its
mass is 1.02 times ten to the 26 kilograms.
Just like Uranus, the planet has three main layers: the upper atmosphere, a
mantle of water, ammonia and methane ices and a rocky core comprised in nickel and
iron. The upper atmosphere is extremely cold at 59 degrees Kelvin but its
interior is over 7,000 degrees Kelvin. Neptune's magnetic field is also very
strange. First, it is set 44 degrees away from the poles of the planet and is
lopsided, meaning that the field is more powerful on one side. However, the field
is still extremely strong, 27 times stronger than Earth's.
Neptune like all the other gas giants has a ring system. It has five main rings
which like Uranus, are made of dark material and dust, which is largely
invisible to the naked eye. Let's look at the orbit and rotation of Neptune.
Neptune actually has one of the most circular orbits out of any of the
planets, with an average orbital radius of 4.5 billion kilometers. At perihelion,
or it's closest distance to the Sun, the planet is 4.46 billion kilometers
away, while at aphelion or it's farthest distance from the Sun. the planet is 4.54
billion kilometres away. Neptune's day is 16 hours and 6 minutes
long, the third quickest in the solar system.
However, it's year is 164 Earth years which means that the Neptunian calendar
would have almost 90,000 days for every year. It has an axial tilt of 28.3
degrees which is similar to Earth's and therefore has similar seasonal patterns.
However, the seasons of Neptune lasts over 41 years so the poles of planet are
subjected to extremely long exposures of light and dark. Now let's look at the
moons of Neptune. Neptune has 14 known moons with only one major moon. This
major moon is known as Triton with a diameter of 2707 kilometers, the seventh
largest moon in the solar system. It dwarfs the other moons of Neptune, the
next largest being Proteus with a diameter of 420 kilometers. But Triton
is a very strange moon. It is the only moon in the solar system that orbits in
retrograde to its host planet. What this means is that it orbits in the opposite
direction to Neptune's rotation. When planets form, they have a ring of
material that rotates in the same direction to the planet and eventually
forms the moons. This would suggest that Triton is a
captured object rather than a moon that formed with the planet.
It most likely came from the Kuiper Belt, the ring of objects far beyond
Neptune and was captured in the planet's gravity. The surface of the Moon
is mostly made of frozen nitrogen and rock. These two materials are seen
directly adjacent to each other, forming cratered and smooth plains. Plumes of
material have also been spotted erupting from the surface but the composition of
these plumes is unknown. While Neptune's surface temperature is 59 degrees Kelvin,
Triton's surface temperature is a blistering 34 degrees Kelvin because the
icy surface reflects the heat from the Sun. It is the coldest known object in
the solar system. Let's explore some interesting features of Neptune. Neptune
was the only planet in the solar system that wasn't discovered by the naked eye or
telescope and instead, was predicted. This was through Uranus' orbit which seemed to
deviate from its predicted course. Some of the theories that were considered was
that Newton's law of gravity does not work over long distances, such as the
distance that Uranus orbits. However, French astronomer Urbain Le Verrier
predicted that an unnamed body was pulling Uranus from its predicted orbit.
He determined the position of this mystery planet and sent his findings to
Johann Galle, a German astronomer. Within a single night, the planet was found with
its location being barely a degree from where Le Verrier predicted it to be.
However, there was some controversy with who actually made the discovery. In the
exact same month, John Couch Adams, a british astronomer also calculated where
the missing planet should lie in the sky. Completely independently of each other,
both Adams and Galle discovered Neptune but because Le Verrier had
predicted it first, there was a dispute over who actually discovered the planet.
After many years of debate, they were both given joint credit for its
discovery. The only spacecraft to ever go past Neptune was Voyager 2, in 1989, so
this planet is probably the one that we know the least about. All the close-up
photos of the planet and its moons were from the spacecraft. However, NASA
recently released a concept idea that detailed a new mission known as TRIDENT
which would do a flyby of Triton and Neptune. This mission makes use of a
short time window where gravity assists will be able to propel the spacecraft to
Neptune by 2038. During this mission it will come as close as 500 kilometres
above Triton's icy surface and would completely map the rest of the moon's
exterior. I feel like this would definitely be a great mission to
undertake as with one spacecraft to ever get close to the planet and its moons,
there is definitely a lot more to learn about these objects. And if you stayed
with me throughout this entire series, I want to thank you for watching and I
hope you enjoyed it. If you haven't, then make sure you go back and watch the
planets of the solar system playlist. Remember to subscribe to the channel and
until next time. Goodbye.