Juno Flyby Io Illuminated by Jupiter’s Reflected Sunlight

NASA has unveiled a high-resolution image captured by the Juno spacecraft during its recent encounter with Jupiter’s moon Io on December 30, 2023. This image not only showcases remarkable details of the volcanic satellite but also features an unusual lighting effect.

During its close flyby of Io in December, the robotic Juno orbiter achieved the closest approach to the moon since the Galileo mission over two decades ago. This event also marked a significant advancement in photographic capability, courtesy of JunoCam, which boasts a resolution of 15 km/pixel (9.3 miles/pixel) from a distance of 4,300 km (2,700 miles).

As Juno traversed over Io’s southern hemisphere, JunoCam transmitted high-resolution images capturing various features of the moon, including active volcanoes emitting sulfur clouds into space.

Io’s Peculiar Illumination

However, the latest processed image unveils an intriguing occurrence. Typically, celestial bodies in space are sharply illuminated by the Sun on one side while the other side remains shrouded in darkness. Yet, the new image depicts one side of Io brightly illuminated, with the night side appearing almost equally luminous. This phenomenon arises from the brighter side being illuminated directly by the Sun, while the night side receives illumination from “Juptershine” – sunlight reflected by Jupiter back onto Io.

A comparable phenomenon occurs during a New Moon phase when, despite the Moon supposedly being in complete darkness, it is faintly illuminated by Earthlight. During a New Moon, the Moon faces a fully illuminated Earth, resulting in sunlight being reflected onto it, making it faintly visible from Earth under favorable conditions.

Given Jupiter’s size, approximately eleven times that of Earth, Io receives nearly as much illumination from it as it does from the Sun.

Read the original article on: New Atlas

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