(NASA) As of noon (Pacific time) today, July 2, NASA’s Juno mission was 1.79 million miles (2.88 million kilometers) from Jupiter — and closing. The solar-powered spacecraft will cross the orbit of the outermost Galilean moon, Callisto, on July 3 at about 11 a.m. PDT (2 p.m. EDT). The orbits of Ganymede, Europa and Io (the other Galilean moons), will be crossed on July 4 at about 4 a.m. PDT (7 a.m. EDT), 10:30 a.m. PDT (1:30 p.m. EDT) and 2:15 p.m. PDT (5:15 p.m. EDT) respectively. These four largest moons of Jupiter are named the Galilean moons because they were discovered by Galileo Galilei in 1609.
“The atmospheric pressure at Earth is about one bar; at the centre of Jupiter it is 80 million bar,” explained mission team-member Fran Bagenal from the University of Colorado. “That’s like a thousand elephants, one on top of the other, with the bottom elephant standing on a stiletto.”