“We just need to go back” – Uranus’ moon Ariel may have hidden a 100-mile-deep ocean

Evidence is building that Uranus' moon Ariel may once have contained a vast ocean beneath its frozen exterior. Research published in Icarus explores how that hidden ocean may have changed over time and suggests it could once have been more than 100 miles (170 kilometers) deep. By comparison, the Pacific Ocean has an average depth of about 2.5 miles (4 kilometers).

"Ariel is pretty unique in terms of icy moons," said paper co-author Alex Patthoff, a Planetary Science Institute senior scientist.

Ariel is the brightest of Uranus' moons and the second closest to the planet. At only 720 miles (1,159 km) across (the distance from PSI in Tucson to Salt Lake City, Utah), it ranks as the fourth-largest moon in the Uranian system.