Jupiter is the largest planet in the Solar System and the fifth planet from the Sun. Jupiter is a gas giant, both because it is so large and made up of mostly hydrogen. The other gas giants are Saturn, Uranus, Neptune, and the hypothetical Planet Nine (though Uranus, Neptune, and Planet Nine are sometimes classified as ice giants). Jupiter orbits 1,426,000,000 km away from the Sun. The planet is named after Jupiter, the supreme god of the Romans, also called Zeus by the Greeks. His sacred animal is the eagle and his wife is Hera or Juno; the latter's namesake is the asteroid 3 Juno.
Jupiter was estimated to be 700,000 km across when it was born; it is shrinking at 0.5 centimeters every year. The planet has a radius of 69,911 kilometers; 1,300 Earths could fit inside of it. It is also famous for its Great Red Spot, which is a giant spinning storm that is 1,5 times the width of the Earth and has been raging for over 350 years. On 7 July 1992, the comet Shoemaker-Levy 9 broke into several pieces; all of which crashed into Jupiter. Jupiter has a faint ring system.
Jupiter was originally known to have 67 moons, but 12 more were discovered in July 2018, raising the total to 79. The four largest are called the Galilean Moons because they were discovered by Galileo before all of the other ones:
|Io||3,820 km||Covered with volcanoes and sulfur.|
|Europa||3,122 km||Its surface is cracked water ice. It could have an ocean below its icy surface.|
|Ganymede||5,262 km||The largest moon in the Solar System, even larger than the planet Mercury.|
|Callisto||4,820 km||Has the oldest surface in the Solar System (4 billion years old) that remains unchanged|
|Other notable moons|
|Amalthea||~170 km||Red surface due to sulfur compounds from Io.|
|Thebe||98 km||Consists of porous solid water with unknown amounts of other materials.|
All of them are named after the lovers of Zeus (whose Roman equivalent is Jupiter).
Jupiter orbits the Sun at a distance of million kilometers. NASA’s Juno spacecraft was launched in . On July 4, 2016, Juno arrived at Jupiter and is currently orbiting it. Juno is taking pictures of Jupiter’s north and south poles.
Jupiter is a binary companion to the Sun. The Sun and other planets orbit the Solar System barycenter, but the planets are too small and thus their gravitational pulls fail to bring the barycenter out of the Sun. But Jupiter is so large, its gravitational pull tugs the barycenter outside of the Sun.
By now, you should have a good understanding of the planet Jupiter. See if you can get all correct on the following test: