NASA has spotted auroras on Uranus. Excerpt:
Uranus is the third largest planet in the solar system after Jupiter and Saturn. It’s quite a bit smaller than Saturn, actually, with a diameter of 15,759 miles (25,362 km). Saturn is more than twice as large, but you could still fit 63 Earths inside Uranus. The Planet appears as a uniform blue-gray globe from a distance, but there are some subtle pattern in the clouds when viewed in certain wavelengths of light. It also has a ring system — it’s no match for the majestic rings of Saturn, but it’s got Jupiter beat in that department. In addition, Uranus has the distinction of rotating with an axial tilt of 97 degrees — almost parallel to the plane of the solar system. Astronomers hypothesize it was struck by a smaller planet in the distant past that tipped it over on its side.
The above images show bright auroras glowing in the clouds of Uranus, a phenomenon that was only confirmed in 2011. Astronomers had previously seen auroras on other gas giants like Jupiter and Saturn, but never Uranus. Auroras are caused by streams of charged particles like electrons picked up by the solar wind or from a planet’s own ionosphere. They are channeled into the upper atmosphere by the planet’s magnetic field, where they interact with gas molecules like oxygen and nitrogen. The ionized gas then gives off light, which we can observe.
Insert obligatory “Uranus” pun here.
It’s a common observation among astronomers that the universe is not only stranger than we imagine, but stranger than we can imagine. Not only is the universe pretty strange in places, our own solar system is pretty weird. The semi-cool outer gas giants are interesting and strange, and it’s only recently we’ve started getting good looks at them.
Like many biologists, though, I’m still holding out for whatever we may find under the icepack on Europa.