Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with a mass slightly less than one-thousandth of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn, Uranus and Neptune. Together, these four planets are sometimes referred to as the Jovian or outer planets.
The planet was known by astronomers of ancient times and was associated with the mythology and religious beliefs of many cultures. The Romans named the planet after the Roman god Jupiter. When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, making it on average the third-brightest object in the night sky after the Moon and Venus. (Mars can briefly match Jupiter's brightness at certain points in its orbit.)
Jupiter is primarily composed of hydrogen with a quarter of its mass being helium; it may also have a rocky core of heavier elements. Because of its rapid rotation, Jupiter's shape is that of an oblate spheroid (it possesses a slight but noticeable bulge around the equator). The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence and storms along their interacting boundaries. A prominent result is the Great Red Spot, a giant storm that is known to have existed since at least the 17th century when it was first seen by telescope. Surrounding the planet is a faint planetary ring system and a powerful magnetosphere. There are also at least 64 moons, including the four large moons called the Galilean moons that were first discovered by Galileo Galilei in 1610. Ganymede, the largest of these moons, has a diameter greater than that of the planet Mercury.
Jupiter has been explored on several occasions by robotic spacecraft, most notably during the early Pioneer and Voyager flyby missions and later by the Galileo orbiter. The most recent probe to visit Jupiter was the Pluto-bound New Horizons spacecraft in late February 2007. The probe used the gravity from Jupiter to increase its speed. Future targets for exploration in the Jovian system include the possible ice-covered liquid ocean on the moon Europa.
The second most known meaning of Jupiter is that of a God in the Roman pantheon. Jupiter or Jove was the king of the gods, and the god of sky and thunder. He is the equivalent of Zeus in the Greek pantheon. As the patron deity of ancient Rome, he ruled over laws and social order. He was one of three gods of the Capitoline Triad, along with Juno and Minerva. The most important temple of the Roman Republic was dedicated to Iuppiter Optimus Maximus ("Jupiter Best and Greatest").
Jupiter's Travels is a book by Ted Simon which narrates his four-year journey through 126,000 km across 45 countries on a Triumph Tiger 100 500 cc motorcycle from 1973 to 1977 and was first published in English in 1979.
Notes and references
- As of 2008, the largest known planet outside the Solar System is TrES-4.
- Stuart Ross Taylor (2001). Solar system evolution: a new perspective : an inquiry into the chemical composition, origin, and evolution of the solar system (2nd, illus., revised ed.). Cambridge University Press. p. 208. ISBN 0-521-64130-6.
- Ted Simon, "About the bike...", Official website, http://www.jupitalia.com/bike.html, retrieved 2011-01-15
- Whitmore 1, John (6 November 2004). "We're all the same". The Daily Telegraph. http://www.telegraph.co.uk/motoring/2731393/Were-all-the-same.html.