Winds of Jupiter
Jupiter is the largest planet in the solar system and one of the most interesting to view. Its distance from the sun means that temperatures in the atmosphere of this “gas giant” are extremely cold. But heat from deep within Jupiter rises through layers of hydrogen and helium, resulting in temperature fluctuations that cause massive storms to rage at wind speeds of 300-800 kph.
From north to south, the ever-changing surface of Jupiter appears divided as these storms swirl within “belts” and “zones” parallel to the equator. Lightening within the storms could indicate regions of water vapor which then give way to an atmosphere much like that of the Sun; about 80% hydrogen, 15% helium, and a small mix of other elements. The “great red spot” is a cyclonic storm that has been a feature on the southwest hemisphere of Jupiter for possibly hundreds of years.
Frozen gases in the upper atmosphere reflect the light of the sun, causing Jupiter to be the second brightest planet visible from earth. A day on Jupiter is the briefest of any other planet in the solar system. Jupiter rotates on its axis in only 10 hours, and orbits the sun in 12 years from an average distance of 780 million kilometers.
The Galilean Moons
Within Jupiter’s stormy atmosphere, gaseous elements like hydrogen and helium gradually increase in pressure before reaching a critical density when they become metallic.
The layer of metallic hydrogen has created a magnetosphere around Jupiter that is not only stronger than earth’s, it surrounds the four “Galilean” moons of Jupiter and protects them from the atmospheric vacuum within the solar system.
In 1610, Galileo discovered Jupiter’s four largest moons. Centuries later, powerful telescopes and orbiting spacecraft have allowed astronomers to identify at least 63 more
Io is the closest. The gravitational effects from its proximity to Jupiter, as well as its orbital resonances with Ganymede and Callisto, causes a “push and pull” effect that creates friction within Io’s core. As a result, there are hundreds of volcanoes spewing sulfur dioxide into the moon’s thin atmosphere, causing it to appear yellow, green, and orange.
Europa is just a little smaller than Earth’s moon. It is believed to have a terrestrial surface covered with oceans locked under solid ice. Lines on the surface of the ice could be caused by gravitational pressures related to its proximity to Jupiter and the other moons, or might be the result of geologic activity beneath the surface. Questions surrounding Europa include whether the atmosphere is warm enough to sustain liquid oceans beneath the ice and if so, could life forms be evolving?
Ganymede is the largest moon of Jupiter as well as the largest in the solar system. About one-third of Ganymede is terrestrial, with a geologic surface of cooled volcanic rock that was heavily impacted by craters during the formation of the solar system. The rest of the moon is made up of a lighter, reflective surface thought to be a mix of silicate and ice. Oxygen present in the atmosphere could be in the form of O3, an ozone layer, possibly making it the most habitable place in the solar system besides Earth.
Callisto, on the other hand, is farthest away and much colder. Callisto is the same size as Mercury, but much lighter since its core is believed to be rock rather than metal. Its thin, carbon-dioxide atmosphere isn’t as sheltered from the solar winds as the other three moons. The ancient, cratered surface of Callisto is geologically stable, and scientists theorize that it could be a likely place to build a human settlement during an age when space exploration takes us to the outer boundaries of the solar system.