Jupiter (disambiguation)
Jupiter is the fifth planet from the Sun. It is a gas giant (also known as the Jovian planet).
Parameters for classification as a planet
Jupiter is classified as a planet by the International Astronomical Union for meeting the following criteria:[1]
- Orbits the sun;
- Has mass sufficient for its gravity to form a nearly round shape;
- Has mass sufficient for gravity to clear a path in its orbit.
Physical characteristics
Jupiter is a little more than five times further away from the Sun than Earth (5.2 AU) and is the most massive of the planets with a total mass of about 318 times that of Earth (318 Earth masses) Its total mass is about 2.5 times all the other planets combined. It is composed largely of hydrogen and helium. Jupiter's strong internal heat creates a number of semi-permanent features in its atmosphere, such as cloud bands and the Great Red Spot.
Jupiter's great spot
Jupiter's red spot is believed to be a giant hurricane a strom rotating within the planet clouds. The first recorded observation was made by Italian-French astronomer Jean-Dominique Cassini in 1655. Three-hundred years later it is still active. The spot is a cold, high-pressure area, 2 to 3 times the diameter of Earth. Its outer edges make a complete rotation in a counter clock-wise motion about once every six days.[2]
The red spot rises about 8 km above the surrounding clouds. Its red colour is a mystery but current theories posit that it may be caused by material dredged up from the surface of the planet.[3]
Oval BA
Jupiter shows a number of other storms that are much smaller than the Great Red Spot. However, in June of 2000, a number of these smaller stroms were seen to coalesce and form a larger storm center. The storm, labled Oval BA (aka Red Spot Jr.) has since developed a reddish colour and looks very much like the Great Red Spot though much smaller.[3]
Rotational characteristics
Jupiter has a rotational period (a complete rotation on its axis) of 9.842 hours and a polar tilt of 3°.[4]
Orbital characteristics
Jupiter has an orbital period (sidereal year) of 11.68 earth years. At is closest approach to the Sun (perihelion) it is nearly 5 times the distance of the Earth from the Sun (4.95 AU). At its furthest distance from the Sun (aphelion) it is 5.45 AU from the Sun.[4]
Natural satellites
Jupiter has sixty-three satellites. The four largest, Ganymede, Callisto, Io, and Europa show similarities to the terrestrial planets, such as volcanism and internal heating.[5] Ganymede, the largest satellite in the Solar System, is larger than Mercury.
References
- ↑ Honey, I Shrunk the Solar System NASA. “The International Astronomical Union has decided that, to be called a planet, an object must have three traits. It must orbit the sun, be massive enough that its own gravity pulls it into a nearly round shape, and be dominant enough to clear away objects in its neighborhood.”
- ↑ Galileo, Cassini, and the Great Red Spot NASA
- ↑ 3.0 3.1 Jupiter's new red spot NASA
- ↑ 4.0 4.1 The orbits of the planets National Maritime Museum
- ↑ Pappalardo, R T (1999). Geology of the Icy Galilean Satellites: A Framework for Compositional Studies. Brown University. Retrieved on 2006-01-16.
External Links
- Jupiter's Great Red Spot Hubble Heritage Project