NASA Is About To Fly By The Largest Moon In The Solar System

https://www.npr.org/2021/06/07/ [login to see] /nasas-juno-spacecraft-will-get-a-close-look-at-jupiters-moon-on-monday
Jupiter's moon Ganymede will have a visitor from Earth on Monday. At 1:35 p.m. ET, NASA's Juno spacecraft will zoom by, just 645 miles above the surface of the solar system's largest moon.

It's the first time a probe has made a close-up visit to Ganymede since the Galileo mission flew by in 2000.

Ganymede is an icy moon, and icy moons are attracting a lot of attention from planetary scientists these days. Ice is not unusual on moons, there's even some on the Earth's moon. But some of the large moons around the outer planets have significant amounts of water, and some are thought to have liquid oceans under their icy surfaces.

Researchers have come to understand that these watery worlds could be home to some kind of life, even though they are far from the sun. Gravitational tugging from the giant planets they orbit may help explain how the ice is able to melt.

Scientists used to think the heat would have to come from a planet's star, in our case, the sun. "I think we've realized in the last few decades that the idea of habitability has extended," says Scott Bolton of the Southwest Research Institute, who is principal investigator for the Juno mission.