Eclipsed Moons of Jupiter Still Shine
Normally, if a planet blocks the sun from shining on its moon, there would be no light left to make that moon continue to glow, but in the case of the four largest moons of Jupiter, that just isn’t so. Even when they are not directly illuminated by the Sun, Ganymede, Io, Europa and Callisto still have a healthy glow.
This strange occurance is thought to happen thanks to the upper atmosphere of the hulking gas giant the satellites orbit. With 67 moons total and it’s massive size, Jupiter is one impressive world and the largest in our solar system. It’s gravitational pull is so strong it keeps the volcanoes on Io–it’s innermost Gallilean moon–hot enough to erupt recently, thanks to a bit of friction.
The researchers discovered the glowing of eclipsed moons while using both the Subaru telescope and the Hubble (which has been seeking astral light for some time according to this Inquisitr report) to detect the diffuse light from the most distant parts of the universe They hoped to spot dark objects that would block out light, and thus, help determine the brightness of that light. They had assumed the moons of Jupiter would be dark during their eclipsed phase and planned to use their darkened state to help block out any background emissions.
However, even while eclipsed, the four Galilean moons were not nearly as dark as they’d expected, according to Kohji Tsumura, an astronomer at Tohoku University in Japan. “This is a serendipitous discovery, which makes us surprised and excited,” Tsumura said. Jupiter’s clouds arise from tiny haze particles which are assumed to form in the upper atmosphere of the planet, and Tsumura believes they could study the spectral light from the eclipsed moons to understand more about these hazes and the atmosphere in which they reside. A clearer understanding of Jupiter’s atmosphere may help them to better understand the atmospheres of some exoplanets.
Ground-based telescopes have been used to detect exoplanet atmospheres. To date, scientist have found several key gases, including carbon dioxide, silicates, and water vapor. But most other discoveries concerning planetary gases were made using space telescopes, which don’t have to contend with the gases of our own world while they are at it.
