Neptune Is the Furthest Planet From the Sun, But It Still Experiences Auroras

Key Takeaways on the Furthest Planet From the Sun

• Neptune is the furthest planet from the sun in our Solar System. Even when Pluto was still designated a planet, it has an elliptical orbit, bringing it closer to the sun than Neptune for 20-year periods.
• Neptune is 2.793 billion miles away from the sun. That’s 30 times further from the sun than Earth.
• Although Neptune is the furthest planet from the sun, new studies have found that the ice giant still experiences auroras.

Pluto may be thought of as the most distant planet from the sun in our Solar System, but in 2006, the International Astronomical Union downgraded it to a “dwarf planet.” In fact, for long periods, of around 20 years, it is closer to the sun than Neptune; that’s due to Pluto’s elliptical orbit.

Hence, Neptune is the most distant planet from our Solar System’s sun, orbiting it at a staggering distance of 2.793 billion miles (4.5 billion kilometers). That makes it 30 times further from the sun than Earth, and it’s the only planet in our Solar System that can’t be seen with the naked eye.

Read More: Why Are Uranus and Neptune So Different From Each Other?

Neptune: The Furthest Planet From the Sun

Compared to other planets in our solar system, relatively little is known about Neptune. Alongside Uranus, much of our knowledge of the planet comes from NASA’s Voyager 2 space probe when it flew by the distant planet on August 25, 1989, says Henrik Melin, an associate professor at Northumbria University. “So, we don’t really know all that much about Neptune.”

The eighth planet in our solar system, Neptune, is known as an ice giant with an atmosphere composed of hydrogen, helium, and methane. It’s the presence of methane that gives the planet its blue color. In a nod to the many unknowns about Neptune, some scientists are questioning this ice giant claim, according to a study in Icarus. Some researchers, according to Cornell University, have even stated that it may be comprised of more rock than previously believed.

If a space traveler were to spend a day on Neptune, it would last just 16 hours. That would not be a comfortable time, as Neptune is known to be ravaged by intense storms with winds reaching almost about 1367 miles per hour (2,200 kilometers per hour), according to the National History Museum, and temperatures that can drop as low as negative 417 degrees Fahrenheit (negative 214 degrees Celsius), according to University College London.

Both recorded wind speeds and temperatures are amongst the lowest ever recorded in our solar system. One enormous storm system known as the “Great Dark Spot,” spotted in the 1989 flyby, was so large that the entire Earth could have fit inside it, according to NASA.

How Many Moons Does Neptune Have?

A giant planet, Neptune is 30,775 miles (49,528 kilometers) in diameter and also has 16 moons. Triton is the largest of those, and unlike the other moons around Neptune, it orbits in the opposite direction to the planet’s rotation.

“It’s a strange Moon, because it’s not really a moon in the traditional sense,” says Melin. That’s 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 states that our knowledge of Neptune is slowly growing thanks to observations made by NASA’s Hubble and James Webb Space Telescope (JWST). Exactly why we should study this planet is that its size is similar to that of many other planets observed outside our Solar System.

“By looking at Neptune, we can sort of understand how these planets operate, and we can transfer that knowledge to these thousands of planets that are discovered elsewhere within 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. That the planet has such activity was only recently discovered through JWST observations, according to a report from Northumbria University. Auroral activity has been observed on other planets, including Jupiter, Saturn, and Uranus. It’s thanks to images and the discovery of trihydrogen cation emissions from Neptune, which can be created by auroral activity, that they made this find, according to NASA.

Melin and his team also observed a bizarre change in the planet’s atmosphere, noting that Neptune’s upper atmosphere has cooled by several hundred degrees since the last observations in 1989.

“The temperature in 2023 was just over half of that in 1989,” he says, adding that exactly why that has occurred remains unclear.

One theory for Neptune’s auroral activity is that Triton is an “active moon” with geothermal activity. Another possibility is that Neptune’s auroras are triggered by interactions with solar winds, in a similar way to the spectacular events we see on Earth.

If the former proves to be the case, he says, it’s an exciting possibility as it could make the moon a candidate for the discovery of life beyond our planet.

“Active moons are basically 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 “top contender” for the presence of 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 the Dark for 42 Years

Neptune takes 165 Earth years to orbit the sun. But its orbital path is not the most fascinating amongst the major planets in 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 is exposed to the light, while the other remains cloaked in darkness for 42 years. That’s due to its extreme tilt as it moves around the sun, giving it the nickname the “sideways planet,” according to a report in EBSCO.

Two theories exist as to how this came to be: either a massive collision early in the planet’s formation that toppled it, or the gravitational pull from Jupiter or Saturn.

Read More: The Outer Moons of Uranus Have Been Gathering Dust, Darkening Their Front Sides

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