- Jupiter is a large ball of gas/liquid with a composition
very similar to the Sun - mostly hydrogen with some helium.
- Jupiter is 1/1000th the mass of the Sun.
- Despite its sun-like composition, Jupiter would have had to have been 80 times more massive in order to be a star.
- Due to gravitational compression Jupiter was hot when
it first formed. It is still cooling off even today.
- Infrared images of Jupiter reveal that it emits about twice as much energy as it
receives from the Sun.
- In the absence of sunlight Jupiter would have a
temperature about 100 degrees above absolute zero and would glow dimly in the infrared part of the spectrum.
- We perceive the top of Jupiter's clouds as
its ``surface" even though it has no solid surface.
- Jupiter is gaseous on the outside. That gas liquifies under pressure at greater depths.
- The transition is not abrupt (e.g. like an ocean). As one proceeds deeper and deeper into Jupiter the atmosphere becomes gradually denser and ultimately indistinguishable from a liquid.
- The cloud decks consist of
- Ammonia (top deck, bright white)
- Water (bottom deck, dull white)
- Ammonium Hydrosulfide (middle, red/brown)
- All of the above cloud materials are "white." The coloration of the clouds must come from traces of other compounds.
- The clouds on Jupiter have a banded appearence -- dark belts
and bright zones corresponding to regions of high and low
- Strong winds blow at the boundaries between the belts and zones.
- The brighter bands are regions of upwelling atmosphere
capped by bright white ammonia clouds.
- This circulation is related to the "Hadley circulation" observed on Earth.
- On Earth this circulation is driven by warm air rising at the Equator and cold air sinking at the poles. The circulation breaks up between the equator and the pole due to the rotation of the Earth.
- The ``Great Red Spot" is larger than
the Earth and is a "storm" which has persisted for at least 300 years.
- The Red Spot is just one of many "oval" storms that come and go on Jupiter (and the other Jovian planets).
- Jupiter rotates rapidly (about once every 10 hours!).
- It rotates more rapidly than any other planet in the Solar System despite its immense size.
- The rotation is so rapid that Jupiter is noticeably
oblate (larger diameter at the equator, small diameter at the poles).
- Jupiter is mainly made of hydrogen and helium.
- At the high pressures of Jupiter's interior hydrogen
gas becomes a liquid.
- At the highest pressures near the center the
liquid hydrogen conducts electricity -- liquid metallic hydrogen.
- Rapidly rotating planets with electrically
conducting liquid interiors have strong magnetic fields (e.g. Earth).
Jupiter's magnetic field is the strongest of any planet in the Solar System.
- Its influence on the solar wind extends all the way out to the orbit of Saturn.
- If it were visible from Earth, the magnetosphere would appear as large as the Full Moon on the sky.
- The strong magnetic field produce intense
radiation belts near Jupiter and polar aurorae.
- Jupiter has a tenuous ring and about 60+ satellites both large and small.
Revised November 30, 2007