NASA Astronomy Picture of the Day 13 June 2023: Moons crossing Great Red Spot on Jupiter

Today’s NASA Astronomy Picture of the Day is a snapshot of Jupiter’s two Galilean moons, Europa and Io, crossing the gas giant.

Jupiter’s two Galilean moons were snapped crossing the great red spot by NASA spacecraft. (NASA/ESA/JPL/Cassini Imaging Team/SSI)

Jupiter has been shocking astronomers ever since astronomer Galileo Galilei started recording its mysteries as far back as 1610. Jupiter is also known as the Gas Giant as it has a dense atmosphere of hydrogen and helium with windy clouds of ammonia. It is the fifth planet in the solar system, and it is by far the biggest one. In fact, it is twice as big as all the other planets in our solar system combined. It also has the most moons in the solar system, with 92 confirmed moons with orbits, according to International Astronomical Union's Minor Planet Center.

Today's NASA Astronomy Picture of the Day is a snapshot of Jupiter's two largest moons, Europa and Io, crossing the gas giant. With a radius of almost 1821 kilometers, Io is the third-largest of Jupiter's four Galilean moons. On the other hand, Europa is the smallest Galilean moon but has more water than Earth! The two moons were captured crossing Jupiter's Great Red Spot, the largest storm in our solar system, by NASA's Cassini spacecraft.

Tech used to capture the picture

The robotic spacecraft had several tech instruments onboard to capture objects in space, such as the Visual and Infrared Mapping Spectrometer (VIMS). According to NASA, VIMS was two cameras in a single instrument: one measured visible wavelengths, the other measured infrared, and they helped scientists study the composition of Saturn's ring and moons, and the atmospheres of Saturn and Titan, among other things.

NASA's description of the picture

Jupiter's moons circle Jupiter. The featured video depicts Europa and Io, two of Jupiter's largest moons, crossing in front of the grand planet's Great Red Spot, the largest known storm system in our Solar System. The video was composed from images taken by the robotic Cassini spacecraft as it passed Jupiter in 2000, on its way to Saturn. The two moons visible are volcanic Io, in the distance, and icy Europa. In the time-lapse video, Europa appears to overtake Io, which is odd because Io is closer to Jupiter and moves faster. The explanation is that the motion of the fast Cassini spacecraft changes the camera location significantly during imaging. Jupiter is currently being visited by NASA's robotic Juno spacecraft, while ESA's Jupiter Icy Moons Explorer (JUICE), launched in April, is en route.