A new animation shows a massive lava lake on the surface of Jupiter’s moon Io. The close-up view was taken by NASA’s Juno spacecraft, which flew within 930 miles (1,500 kilometers) of Io’s volcanic surface in December 2023 and January 2024. These flybys provided the closest view of Jupiter’s deepest moon. There are hundreds of active volcanoes on Io. Their explosions are sometimes so powerful that they can be seen through telescopes on Earth, according to NASA.

New images reveal Loki Patera, a 127-mile (200 km) long lava lake on Io’s surface. Scientists have been monitoring this lava lake for decades. It lies above magma reservoirs beneath Io’s surface. Scott Bolton, principal investigator of the Juno mission, said at a press conference at the European Geophysical Union General Assembly in Vienna on Wednesday (April 16).

“The mirror image of the lake captured by our instruments shows that parts of Io’s surface are glass-smooth and resemble obsidian glass formed by a volcano on Earth,” Bolton said.

Irregular rock islands fill the inner space of the lava lake. “There are incredible details showing these crazy islands in the middle of a potentially igneous lake, surrounded by hot lava,” Bolton said.

Juno’s instruments determined that Io’s surface is smoother than the surfaces of Jupiter’s three other Galilean moons: Europa, Ganymede, and Callisto. Io is slightly larger than Earth’s moon, and its unmolten surfaces are mostly covered with yellow sulfur and sulfur dioxide.