Earth isn’t the only place in the solar system with impressive light shows. New Research Shows Auroras Can Be Seen on Jupiter’s Galilean Moons, Too: the hypervolcanic Io, the frigid Europa, the peculiar Callisto and the gigantic Ganymede.
In two articles published in The Planetary Science Journal, two astronomers report that if you were to stand on Ganymede and Callisto (Jupiter’s satellite), visible auroras would be dancing overhead.
Researchers captured the auroras by looking through telescopes in Hawaii, Arizona and New Mexico. The team spent years watching Jupiter’s shadow swallow the satellites and then reemerge.
Capturing elusive glares on moons can be difficult. But “the auroras are always there when you’re looking at an eclipse,” said Katherine R. de Kleer, a planetary astronomer at the California Institute of Technology and an author on both studies.
Auroras are different from those on Earth. Magnetic fields and energetic particles ejected by the Sun reach Earth and are trapped by our planet’s magnetic bubble. Those particles rush toward the two magnetic poles and collide with gas molecules in the upper atmosphere, briefly energizing them and releasing various shades of visible light.
But apart from Ganymede, Jupiter’s large moons lack magnetic bubbles. Its noxious atmosphere—in part courtesy of the moon’s epic volcanic eruptions—regularly spills into space.
The extremely thin atmospheres of the moons cause their red auroras to shine much brighter than their green ones. The strangest Galilean satellite, it has a yellow-orange glow similar to that of a lantern. This light show dims shortly after it enters Jupiter’s shadow. After re-emerging and bathing for a few hours in the sunlight, this sickly amber glow burns brightly again.
The underlying goal of this work was to reveal the compositions and behaviors of the atmospheres of these moons.
The colors of the moons’ auroras provide clues to the ingredients in each world’s atmosphere. The dominant atmospheric component of Callisto, Europa, and Ganymede is molecular oxygen, which explains their newly discovered green and red auroral tints. Io’s sickly orange comes from sodium compounds, while a light crimson first described in one of the new articles comes from potassium.
By: ROBIN GEORGE ANDREWS
BBC-NEWS-SRC: http://www.nytsyn.com/subscribed/stories/6665508, IMPORTING DATE: 2023-04-17 21:30:07
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