If you think Earth has seen some weird weather action lately, you should check out what’s happening in the outer rings of the solar system. It’s summer right now for Neptune and Uranus, and has been for years; their seasons are decades-long events. And even for distant ice giants swaddled in methane gas, summer means storms.
On Neptune, a dark storm 6,800 miles wide is currently swirling around in the planet’s northern hemisphere—one of four observed by since 1993. According to a UC Berkeley undergrad Andrew Hsu, the storms show up in different locations every four to six years and last for about two years.
Nestling up next to Neptune’s “dark vortex” are larger patches of white clouds created by gases freezing into methane crystals as air gets pushed up over the disturbance, not unlike the way clouds form over landmasses on Earth. Since the Hubble started tracking the storms, increased cloud activity has been a regular precursor to their appearance.
The vortex visible today, for example, has been developing since 2016, when the Hubble first captured a blaze of bright cloud activity against Neptune’s icy blue depths. This suggests that the systems take a while to build and likely find their roots deeper in the planet’s atmosphere, and perhaps even deeper than that in its superheated ocean-like mantle of water, ammonia, and methane-ices.
Meanwhile, Uranus’s entire polar region is currently ensconced in white, like a cockeyed celestial skullcap. The ice giant is tilted on its axis so that its pole practically points at the Sun—a unique configuration in our solar system indicative of a collision soon after the planet formed. Scientists think this near constant exposure of the northern pole creates atmospheric conditions ripe for enormous polar storms like the one Hubble captured in November 2018.
Uranus is more ice than gas. Even its core is believed to contain icy materials, while most other planets have rocky, molten cores. , it’s the only world that doesn’t give off more heat from its core than it receives from the sun, which could play a role in its storm activity. Another Uranus anomaly is its abnormally wobbly magnetic field, which opens and closes as the planet rotates every 17 hours.
Studying evolving weather systems on planets 2.7 billion and 1.6 billion miles away (respectively, at their closest) is bewildering to say the least. Add in the fact that these blue giants have no solid surface and, in Neptune’s case, a mantle 10 to 15 times the mass of Earth, and you begin to understand why entire programs are dedicated to their observation.
, led by Simon, will continue to analyze planetary weather systems like these two spotted by Hubble in hopes of better understanding the significant diversity within this small clutch of planets that make up home