Neptune’s Weather As Seen From Earth: NASA’s Kepler Catches Planet, Moon Triton In Orbit

neptune-full-disk — Neptune is the eighth planet from the sun, in the outer reaches of the solar system, and its blue color comes from all the methane in its atmosphere. NASA/JPL

Watching Neptune orbit the sun is kind of like watching a dance — it glides across the night sky with its moons swirling around it, a few steps forward and one step back. NASA’s Kepler spacecraft has caught the planet in the outer reaches of our solar system and its observations could help us learn more about the wider universe.

Kepler recently watched Neptune for a couple of months from its position in orbit around Earth, according to NASA’s Goddard Space Flight Center. It was collecting data on the planet’s fluctuating brightness, which is a measure of how much sunlight the planet is reflecting.

It’s not just for fun: “Kepler’s observations of Neptune pave the way for future studies of weather and climate beyond our solar system,” NASA said. That’s because things like cloud movement can affect how much sunlight is reflected. And Neptune has a lot of weather to observe, including its winds, which NASA says are nine times stronger than the winds on Earth and even more powerful than they are on Jupiter, the largest planet in the solar system.

The bonus of Kepler’s observations was seeing Neptune (video below) travel across the sky, the dot of its moon Triton doing laps around it and another moon, Nereid, trailing behind. Kepler also catches Neptune seemingly stopping in its orbit and going backward, in retrograde. But it’s actually a trick on the eye, caused by Kepler’s motion around the Earth — Neptune is always moving east, moving forward.

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Kepler was originally designed and is known for discovering exoplanets, planets that orbit other stars. Its greatest finds include Kepler-22b, the first it found in a star’s habitable zone, which is the distance from a star where the temperature is right to support liquid water and thus alien life. Kepler-186f was the first rocky planet it found that was similar in size to Earth, also within a habitable zone.

Neptune isn’t within the sun’s habitable zone — it’s 2.8 billion miles away and orbits only once every 165 years. Although it is so far away, it still has a friend: Pluto. According to NASA, Pluto’s strange orbit brings it inside Neptune for two decades every 248 years.

“Pluto can never crash into Neptune, though, because for every three laps Neptune takes around the Sun, Pluto makes two,” the space agency says. “This repeating pattern prevents close approaches of the two bodies.”

The blue planet, which gets its color from the methane in its atmosphere, also has at least 13 moons — a potential 14th has been spotted but is yet to be confirmed — and six rings to keep it company.