It’s cold in the outer solar system. The planet Uranus, for example, is 20 times farther from the Sun than Earth is. As a result, its 28 known moons all shiver at hundreds of degrees below zero. Yet several of the planet’s bigger moons might have active volcanoes. Instead of molten rock, they’d belch out molten ice – a slushy brew from buried oceans of liquid water.

We don’t know for sure if any of the moons have ice volcanoes, but there’s evidence that they do. The surfaces of the moons are fairly young, for example. That suggests that something is renewing them – like material from the interior. And a couple of the moons appear to be pumping material into the space around Uranus.

Recent observations by Webb Space Telescope found additional evidence for an ocean on the moon Ariel. It’s coated with frozen carbon dioxide. Webb found the layer of C-O-2 is especially thick. And it’s mixed with carbon monoxide. Both compounds should quickly vaporize and drift off into space. Their presence suggests the supply is being renewed – perhaps by volcanoes belching ice from a hidden ocean.

Uranus is putting in its best appearance of the year. The giant planet rises around sunset and is in view all night. It’s brightest for the year, too, although you still need binoculars to pick it out. Tonight, it lines up about half way between the almost-full Moon and the bright planet Jupiter.

We’ll have more about Uranus tomorrow.

Script by Damond Benningfield