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Jupiter – The Giant Planet

Jupiter is a gaseous planet 11 times the size of the Earth. It is the largest planet in the solar system and the fifth planet from Sun at 778 million km, or about 5.2 astronomical units. An astronomical unit is the Earth-Sun distance and is used by astronomers to measure distances in the solar system.  Although it is a huge planet, it spins much faster than the Earth, taking only 10 hours to complete a full rotation. Due to its distance from the Sun, Jupiter takes about 12 years to complete an orbit around the Sun. This follows from Kepler’s third law that the square of the time planets take to orbit the sun proportional to the cube of their heliocentric distance. Mathematically this is written as , where  is the period of the orbit in years and is the distance from the Sun in astronomical units.

              Hubble Maps Jupiter in 4k Ultra HD. Credits: NASA

Jupiter’s atmosphere is made up mostly of hydrogen and helium and the planet does not have a terrestrial surface like our planet. From the images it is possible to see that it is characterized by immense bands and eddies, but the highlight is its iconic Great Red Spot. This red oval is in fact a giant storm, bigger than planet Earth, which has lasted for hundreds of years.

The Great Red Spot. Credits: NASA/JPL/Space Science Institute

Jupiter cannot support life as we know it, but some of its moons have sub-surface oceans, which could support life. Jupiter has more than 90 moons but the largest and most famous are Io, Europa, Ganymede, and Callisto. These are known as the Galilean moons, acknowledging the famous Italian scientist Galileo Galileo for their discovery.

Nine space missions have visited Jupiter, with two orbiting the planet. Juno, the most recent, arrived at Jupiter in 2016 and is still studying the planet, JUICE launched earlier this year, is an ESA mission designed to find out if there are places in the Jupiter system, inside its large icy moons, with the necessary conditions (water, energy, stability, and biological elements) to support life. JUICE will observe closely Europa, Callisto and Ganymede in a number of flybys. It will later enter an orbit around Ganymede to study it in more detail, and is planned to finish its mission in 2035.

JUICE Mission. Credits: ESA/ATG/NASA/J. Nichols/JPL/University of Arizona/DLR

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