It is the reddest object in the entire solar system. We mean a small ball flying in front of Jupiter.

NASA’s Juno mission is nearing its destructive end against Jupiter in 2025. Meanwhile, it keeps sending back amazing images of the gas giant and its many moons, such as this image of Amalthea passing over the Great Red Spot.

What exactly are we seeing? The Juno space probe, which has been orbiting Jupiter since 2016, took this photo on March 7 during its 59th close flyby of the planet. It was 265,000 kilometers away from the clouds.

At first glance, we might think this is just another image of the Great Red Spot and other violent storms on Jupiter. But closer analysis reveals the true protagonist: the moon Amalthea, which is trying unsuccessfully to eclipse the gas giant.

A tiny moon shaped like a potato. Discovered in 1892 by astronomer Edward Emerson Barnard, Amalthea has a radius of 84 kilometers and takes 11 hours and 57 minutes to complete an orbit around Jupiter, meaning it travels at over 31,000 kilometers per hour.

Not only is it very small compared to the planet it orbits, but it also has too little mass to become a sphere, which is why it is often called a “potato moon.”

The reddest object in the solar system. Amalthea is the reddest object in the solar system, although it is difficult to see in the image, unlike Jupiter’s Great Red Spot. Thanks to the Galileo probe, which visited it in 2000, we know that its color is due to the presence of sulfur and tin compounds on its surface, possibly deposited by the active volcano Io, another moon of Jupiter.

Amalthea emits more heat than it receives from the Sun. One explanation could be that Jupiter’s magnetic field induces electric currents within its core. Another reason is that the huge tidal forces caused by Jupiter’s gravity heat up the moon.

The final stage of the Juno spacecraft. Juno’s mission was supposed to end in 2018, but it was extended several times. Having carefully studied Jupiter’s atmosphere and strange winds, photographed its auroras, flown past its moons, figured out what they sound like, and discovered rivers of lava, the probe should say goodbye at the end of 2025.

NASA will end the mission by pitting Juno against Jupiter’s hostile atmosphere to reduce the risk of losing control of the probe and contaminating one of its moons, especially those that may harbor microbial life such as Europa, Ganymede or Callisto.

Image | NASA/JPL-Caltech/SwRI/MSSS

In Hatak | NASA’s Juno probe sent back six photos of its passage through Io, the most inhospitable moon in the solar system.