Saturn has its rings, Mars is red, Jupiter has its storms and Pluto has a heart. But when it comes to Uranus, most people don’t know much about the planet—except the bad puns that go along with its name. But Uranus is slowly coming into focus, and the latest composite image from NASA is one of the coolest yet, including a look at its aurora and the planet's thin ring, reports Mike Wall at Space.com.
The new photos are a combination of images from the Hubble Space Telescope and the Voyager 2 probe, which whizzed by Uranus in 1986, according to NASA. In 2011, Hubble snapped some shots of the light show on Uranus in both visible and ultraviolet light. But then in 2012 and 2014 a team from the Paris Observatory took some images the auroras using the Space Telescope Imaging Spectrograph on the Hubble. They were able to track powerful bursts of solar winds, which cause Uranus' aurora to flare. The team also discovered that the auroras actually rotate with the planet, and detected the planet’s magnetic field for the first time since Voyager.
As Deborah Byrd at EarthSky reports, every planet in the Solar System except Mercury has auroras. The spectacular and eerie bursts of light occur when the upper atmosphere gasses like nitrogen or oxygen interact with strems of charged particles. These particles can come from a variety of source, including solar winds, the planet's ionosphere (the layer of the atmosphere charged by solar or cosmic radiation), or an unusual process called "moon volcanism" (where the moon's volcanic activity emits charged gasses that carry an electrical current along to the planet's atmosphere).
The photo also highlights Uranus’s thin ring. Though it looks like the ring circles the planet around its poles, Wall writes, it actually follows the planet’s equator. That’s because, unlike the rest of the planets, Uranus is oriented on its side, with its axis point toward the sun. Researchers aren’t entirely sure why the planet spins that way, but they believe Uranus was hit at least twice by large objects during its formation.
While the new images are pretty, NASA hopes to eventually visit the icy blue planet, along with Neptune—the only two planets in the solar system that have yet to be orbited by human spacecraft. But with the current focus on ventures to asteroids and Mars, Uranus just needs to sit tight.