Key findings about the planet farthest from the Sun
- Neptune is the farthest planet from the Sun in our Solar System. Even when Pluto was still considered a planet, it had an elliptical orbit, making it closer to the Sun than Neptune for 20-year periods.
- Neptune is 2.793 billion miles from the Sun. This is 30 times further from the Sun than Earth.
- Although Neptune is the farthest planet from the Sun, new research has shown that the ice giant is still experiencing auroras.
Pluto may be considered the most distant planet from the Sun in our solar system, but in 2006 the International Astronomical Union downgraded its status to a “dwarf planet.” In fact, for long periods of time, about 20 years, it is closer to the Sun than Neptune; this is due to Pluto's elliptical orbit.
Consequently, Neptune is the farthest planet from the Sun in our solar system, orbiting it at a staggering distance of 2.793 billion miles (4.5 billion kilometers). This makes it 30 times further from the Sun than Earth, and it is the only planet in our solar system that cannot be seen with the naked eye.
Read more: Why are Uranus and Neptune so different from each other?
Neptune: the farthest planet from the Sun
Compared to other planets in our solar system, relatively little is known about Neptune. Apart from Uranus, most of our knowledge about the planet comes from NASA's Voyager 2 space probe when it flew past the distant planet on August 25, 1989, says Henrik Melin, associate professor at Northumbria University. “So we don't really know that much about Neptune.”
The eighth planet of our solar system, Neptune, is known as an ice giant with an atmosphere made of hydrogen, helium and methane. It is the presence of methane that gives the planet its blue color. According to a study in Icarus. Some researchers, according to Cornell University, have even said that it may consist of more rocks than previously thought.
If a space traveler were to spend a day on Neptune, it would only last 16 hours. It won't be the most comfortable time, as Neptune is known to be subject to the ravages of severe storms, with winds reaching nearly 1,367 mph (2,200 kilometers per hour), according to the National History Museum, and temperatures that can drop to minus 417 degrees Fahrenheit (minus 214 degrees Celsius), according to University College London.
The recorded wind speeds and temperatures are among the lowest ever recorded in our solar system. One huge storm system known as the Great Dark Spot, discovered during a flyby in 1989, was so large that the entire Earth could fit inside it, according to NASA.
How many moons does Neptune have?
The giant planet Neptune has a diameter of 30,775 miles (49,528 kilometers) and has 16 moons. Triton is the largest of them, and unlike Neptune's other moons, it rotates in the opposite direction to the planet's rotation.
“It's a weird moon because it's not really a moon in the traditional sense,” Melin says. This is because Triton originated in the Kuiper belt, in the outer solar system, and was likely captured by the planet's orbit.
Why We Should Study Neptune
Melin argues that our knowledge of Neptune is slowly expanding thanks to observations made by NASA's Hubble and James Webb Space Telescope (JWST). This is why we should study this planet because its size is similar to that of many other planets observed outside our solar system.
“By looking at Neptune, we can understand how these planets work and transfer this knowledge to the thousands of planets discovered elsewhere in our galaxy,” he says.
Read more: The mysterious world of Uranus, the ice giant
Neptune is furthest from the Sun, but still sees auroras
Melin was part of a recent significant discovery about Neptune, which was published in Nature Astronomy. His research concerns aurora activity. According to a report from Northumbria University, such activity on the planet was only recently discovered thanks to observations from JWST. Auroral activity has been observed on other planets, including Jupiter, Saturn and Uranus. According to NASA, it was through imaging and the discovery of emissions of trihydrogen cations from Neptune that could be created by polar activity that they made this find.
Melin and his team also observed bizarre changes in the planet's atmosphere, noting that Neptune's upper atmosphere has cooled several hundred degrees since the last observations in 1989.
“Temperatures in 2023 were just over half of those in 1989,” he says, adding that exactly why this happened remains unclear.
One theory for Neptune's polar activity is that Triton is an “active moon” with geothermal activity. Another possibility is that Neptune's auroras result from interactions with solar winds, similar to the spectacular events we see on Earth.
If the former turns out to be true, he says, it would be an exciting possibility because it could make the Moon a candidate for the discovery of life beyond our planet.
“Active moons are essentially where you want to look for life in the outer solar system,” Melin says, citing the example of Enceladus, a moon of Saturn that is geologically active and contains water; thus, it is considered a “leading contender” for life beyond Earth, according to a report from Oxford University.
“Triton is the number one suspect if there are geologically active moons around Neptune.”
Uranus: Left in Darkness for 42 Years
Neptune rotates around its orbit every 165 Earth years. Sun. But its orbital path is not the most interesting among the large planets of our solar system. That title belongs to its sister ice giant, Uranus, according to the National History Museum.
As Uranus orbits the Sun, one half of it is exposed to light while the other remains hidden in darkness for 42 years. This is due to its extreme tilt as it orbits the Sun, giving it the nickname “sideways planet”. EBSCO reports this.
There are two theories as to how this happened: either a massive collision early in the planet's formation that toppled it, or the gravitational pull of Jupiter or Saturn.
Read more: Uranus' outer moons are collecting dust, darkening their faces
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