NASA's Juno Spacecraft Spots Jupiter's Mysterious Fifth Moon Amalthea

NASA's Juno Spacecraft recently spotted the mysterious fifth moon of Jupiter during its 59th close flyby of the giant planet earlier this year. Jupiter's most famous moons are its four Galilean satellites: Io, Europa, Ganymede and Callisto. Its fifth moon, founded in 1892 by Edward Emerson Barnard, is known as Amalthea. According to NASA's blog, it was spotted as the Juno Spacecraft transited the planet's Great Red Spot, offering researchers a rare view of this small but intriguing natural satellite. 

"NASA's Juno mission captured these views of Jupiter during its 59th close flyby of the giant planet on March 7, 2024. They provide a good look at Jupiter's colorful belts and swirling storms, including the Great Red Spot. Close examination reveals something more: two glimpses of the tiny moon Amalthea," the US space agency wrote in its blog. 

In the pictures released by NASA, Amalthea looked like a tiny dot against the backdrop of one of Jupiter's reddish, dark cloud bands. The moon was also spotted by Juno transiting the Great Red Spot. "At the time that the first of these two images was taken, the Juno spacecraft was about 165,000 miles (265,000 kilometres) above Jupiter's cloud tops, at a latitude of about 5 degrees north of the equator," the space agency wrote. 

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According to NASA, Amalthea has a potato-like shape, lacking the mass to pull itself into a sphere. It circles the giant planet inside Lo's orbit, which is the innermost of the planet's four largest moons, taking 0.498 Earth days to complete one orbit. Amalthea is the reddest object in the solar system. 

Amalthea is shrouded in mystery as scientists suspect that it emits a little more heat than it receives from the Sun. According to Space.com, several theories have been put forward by researchers. One theory suggests that Amalthea receives heat from Jupiter both directly and indirectly. Additionally, heat may be produced by tidal pressures within Amalthea caused by Jupiter's tight grasp. 

Amalthea is often forgotten in scientific discussions, with its significance being clouded by that of its four big giant siblings. Previously, the Galileo spacecraft revealed some surface features, including impact craters, hills, and valleys.