NASA's Juno Captures Rare Images of Jupiter's Tiny Moon Amalthea

NASA's Juno spacecraft has recently captured stunning images of Jupiter, revealing not only the planet's swirling storms and colorful cloud belts but also a tiny moon named Amalthea. This moon, measuring just 84 kilometers (52 miles) across, was spotted transiting the Great Red Spot, a massive storm that has been raging for centuries. The images were taken during Juno's 59th close flyby of Jupiter on March 7, 2024, from a distance of approximately 265,000 kilometers (165,000 miles) above the planet's cloud tops.

Amalthea, discovered in 1892, is notable for being the reddest object in the solar system. Its unusual hue is thought to be influenced by sulfur from the nearby volcanic moon Io. Unlike larger moons that are spherical due to their mass, Amalthea has a potato-like shape, lacking the gravitational pull necessary to form a more symmetrical body. This irregularity is similar to that of Mars' moons, which also exhibit non-spherical shapes.

The moon orbits Jupiter at a distance of about 181,400 kilometers (112,717 miles) and completes a full orbit in just under half a day. It is one of the innermost moons of Jupiter, situated closer to the planet than Io, which is the most volcanically active body in the solar system. The gravitational forces exerted by Jupiter are so strong that they create tidal stresses on Amalthea, potentially causing it to emit more heat than it receives from the Sun. This phenomenon may be due to electric currents induced in the moon's core as it travels through Jupiter's powerful magnetic field.

The recent images of Amalthea were processed by a citizen scientist who enhanced the clarity of the raw data collected by Juno's JunoCam instrument. This engagement with the public is a hallmark of the Juno mission, which has been operational since 2016. The spacecraft was designed not only to study Jupiter's atmosphere and magnetic field but also to involve the public in its discoveries, allowing amateur astronomers to contribute to the mission by processing images and suggesting areas of focus.

Historically, Amalthea was the last moon of Jupiter discovered through direct visual observation, marking a significant milestone in the study of the gas giant's many moons. Today, Jupiter is known to have 95 moons, most of which are captured asteroids. The Juno mission has provided a wealth of data about these celestial bodies, enhancing our understanding of their characteristics and the dynamics of the Jovian system.

As Juno continues its mission, which is expected to last until at least September 2025, it will further explore Jupiter's atmosphere, magnetic field, and its many moons. The spacecraft's findings are crucial for answering fundamental questions about the formation and evolution of Jupiter, the largest planet in our solar system, and its role in the broader context of planetary science.

The images of Amalthea not only highlight the beauty and complexity of our solar system but also serve as a reminder of the ongoing exploration and discovery that continues to unfold beyond our planet. As scientists analyze the data collected by Juno, they hope to unlock more secrets of Jupiter and its intriguing moons, paving the way for future missions and deeper understanding of the cosmos.