New aurorae detected on Jupiter’s four largest moons
Reported by Robert Lea
An artist’s impression of Jupiter’s Great Red Spot and its moon Io
Astronomers have discovered new aurorae over Jupiter’s four largest moons – Io, Europa, A Ganymede and Callisto – observable at visible wavelengths. These reveal the compositions of the thin atmospheres of the Jovian moons in greater detail, including traces of oxygen and sodium, but only minimal water vapour. A team made the discovery while observing the moons as they sat in the shadow of Jupiter using the Keck Observatory’s High- Resolution Echelle Spectrometer (HIRES), as well as high-resolution spectrographs at the Large Binocular Telescope and Apache Point observatories.