Are Uranus and Neptune rock giants and not ice giants?

View larger. | Artist’s depiction of the interior of Uranus as either an ice giant (left) or rock giant (right). A new study suggests both Uranus and Neptune could be rock giants instead of the long-assumed ice giants. Image via Keck Institute for Space Studies/ Chuck Carter/ University of Zurich.

• Uranus and Neptune are known as the “ice giants” in the solar system. Scientists have long thought their interiors are composed mostly of ice. But is that accurate?
• Both planets might instead be rock giants, new research suggests.