NASA spacecraft saw something incredible near Jupiter’s Great Red Spot

Look closer… a little closer…

Come on, you’re going to have to try harder than that. Get in there.

Do you see it now? That’s not a speck of dust on NASA‘s Juno spacecraft camera. That’s a moon, orbiting its enormous mother planet in space.

The teeny tiny moon is Amalthea, and though it was caught zipping in front of the very ruddy eye of Jupiter’s long-lived high pressure zone, astronomers say this moon is in fact the reddest object in the solar system. Scientists think its hue is caused by sulfur from the nearby Jovian moon Io, a world with active volcanoes.

The images released this week were taken as the spacecraft swooped about 165,000 miles above Jupiter’s clouds in March during its 59th close flyby. Citizen scientist Gerald Eichstädt processed the probe’s raw camera data to enhance the clarity of the pictures.

Juno has an instrument, dubbed JunoCam, that was designed not just to take great closeup photos of Jupiter but to engage the public. The science team allows citizens to process the camera’s images and polls the crowd for what to focus on next.

Juno has been orbiting Jupiter for over seven years. The spacecraft is studying the origin and evolution of Jupiter, looking for its core, mapping its magnetic field, measuring water and ammonia in the atmosphere, watching for its auroras, and homing in on Jupiter’s moons and dust rings.

Two images of Jupiter taken by the spacecraft Juno in March reveal tiny Jovian moon Amalthea as it passes by.
Credit: NASA / JPL-Caltech / SwRI / MSSS / Gerald Eichstädt

During its primary mission, the spacecraft collected data on the gas giant’s atmosphere and interior. Among its discoveries was finding that the planet’s atmospheric weather layer extends way beyond its water clouds.

After completing 35 orbits, the spacecraft transitioned to studying the entire system around Jupiter, including its rings and moons. The extended mission will continue for another year or until the spacecraft dies. Juno will eventually burn up in Jupiter’s atmosphere as its trajectory erodes. The spacecraft is not at risk of crashing into and possibly contaminating Jupiter’s moons, some of which may be habitable worlds.

NASA’s Galileo spacecraft took images of Amalthea, center, in January 2000, revealing a world of craters, hills, and valleys. 
Credit: NASA / JPL / Cornell University

Amalthea, just one of Jupiter’s 95 official moons, was first discovered by Edward Emerson Barnard in 1892. It is about 100 miles wide and clumsily shaped like a potato because it lacks the mass to form into a more symmetrical sphere. Almost 25 years ago, scientists got to see this little moon up close with the help of NASA’s Galileo spacecraft, which revealed a pell-mell world of craters, hills, and valleys.

Amalthea is within the orbit of Io, the closest of Jupiter’s four large moons, along with three other oddly shaped mini moons: Metis, Adrastea, and Thebe. It’s so close to Jupiter, in fact, it only takes Amalthea half of a day on Earth to circle its planet.

This moon is a mysterious little place in the solar system. Scientists have discovered that it gives off more heat than it gets from the sun — perhaps a result of Jupiter’s magnetic field stimulating electric currents within its core or the planet’s gravity causing tidal stresses.