9. Jupiter: a giant primitive planet
- All we can see on Jupiter is
clouds, swept into parallel bands of bright zones and dark belts by the planetís
rapid rotation and counter-flowing, east-west winds.
- Jupiter turns to liquid
under high pressures within its interior, so the cloudy atmosphere has no
distinct bottom and Jupiterís weather pattern is free to flow in response to
the giant planetís rapid spin.
- Jupiterís Great Red Spot and
white ovals are huge shallow anti-cyclonic storms, which can have diameters
larger than the Earthís and last for centuries.
- Large whirling storms on Jupiter
gain energy by merging with, and engulfing, smaller eddies. The little storms
pull their energy from hotter, lower depths.
- White clouds of ammonia ice form
in the coldest, outermost layers of Jupiterís atmosphere. Water clouds are
expected to form at greater depths, and ammonium hydrosulfide clouds should condense
between the water and ammonia clouds.
- All of the clouds on Jupiter
ought to be white; their colors are attributed to an active chemistry that
produces complex compounds in small amounts.
- Bolts of lightning illuminate deep, wet
storm clouds on Jupiter.
- When the Galileo spacecraft parachuted a probe into Jupiter, the entry site,
a region of downdraft, was missing the expected three layers of clouds and it
was far drier and windier than anticipated.
- The fierce winds that give rise
to Jupiterís banded appearance run deep, indicating that Jupiterís
ever-changing weather patterns are driven mainly from within, by internal
energy rather than by external sunlight.
- When compared to the outer layers
of the Sun, the outermost atmosphere of Jupiter is slightly depleted in helium,
and enriched in carbon, nitrogen and sulfur by a factor of about three.
- Jupiter is a primitive
incandescent globe that radiates 1.67 times as much energy as it receives from
the Sun, probably as heat leftover from when the giant planet formed.
- Jupiter originated together with
the Sun, and both the giant planet and the star are mainly composed of the
lightest elements, hydrogen and helium.
- If Jupiter was about 80 times
more massive, it could have become a star.
- Jupiter has a non-spherical shape
with a perceptible bulge around its equatorial middle.
- The visible cloud tops and outer
atmosphere of Jupiter form a very thin veneer that covers a vast global sea of
- Most of Jupiterís interior
consists of fluid metallic hydrogen formed under the extreme pressures that
exist inside the planet.
- Jupiter probably has a dense,
molten core with a mass that is less than or equal to 12 times that of the
- By re-creating extreme conditions
like those inside Jupiter, modern laboratory experiments have compressed liquid
hydrogen so that it becomes highly conductive like a metal.
Jupiterís powerful magnetic field is generated by rotationally driven
electrical currents inside its vast internal shell of liquid metallic hydrogen.
- The volcanoes on Jupiterís
innermost large moon Io have turned the satellite inside out. It is the most
volcanically active body in the solar system.
- Ioís volcanoes emit plumes of
sulfur dioxide gas that freeze onto the surface as a white frost.
- Volcanic vents on Io are filled
with melted silicate rocks that are hotter than any place on any planetís
surface, even Venus.
- Changing tidal forces squeeze
Ioís rocky interior in and out, making it molten inside and producing
- A vast current of 5 million
amperes flows between the satellite Io and the poles of Jupiter, generating 2.5
trillion watts of power and producing aurora lights on both the satellite and
the giant planet.
- Jupiterís magnetic field sweeps
past Io, picking up a ton of sulfur and oxygen ions every second and directing
them into a doughnut shaped ring known as the plasma torus.
- There are no mountains or valleys
on the bright, smooth, ice-covered surface of Jupiterís moon Europa; it has few
impact craters indicating a relatively young age.
- Long, deep fractures run like
veins through Europaís icy covering, apparently filled by the upwelling of
dirty liquid water or soft ice. Warmer, slushy material just beneath the crust
also lubricates large blocks of ice that float like rafts across Europaís
- An electrically conducting,
subsurface sea within Europa may be responding to Jupiterís magnetic field,
generating a time-varying magnetism in the satellite.
Scientists speculate that subsurface liquid water in Europa may harbor alien life
that thrives in the dark.
- Jupiterís moon Ganymede is bigger
than the planet Mercury. The satelliteís icy surface has been fractured and
pulled apart, producing a grooved terrain, and surface depressions have been
filled by eruptions from volcanoes of ice.
- Ganymede has an intrinsic
magnetic field, and it is the only satellite that now generates its own
- Jupiterís moon Callisto has one
of the oldest, most heavily cratered surfaces in the solar system. Yet, the
satellite is covered by fine dark, mobile material and it has a lack of small
craters when compared to the surfaces of the Moon and Mercury.
- Like Europa, the outermost large
moon Callisto has a borrowed magnetic field, apparently generated by electrical
currents in a subsurface ocean as Jupiterís powerful field sweeps by. But
Callisto has a largely homogeneous interior without any apparent dense iron
core, and the buried sea has to lie deep enough to not affect its unaltered,
- Jupiterís faint, insubstantial
ring system is made of dust. The ring particles might last for only a few
thousand years, and they must be replenished if the ring system is a permanent
- When interplanetary meteoroids, attracted by Jupiterís
powerful gravity, pound into the small inner moons of Jupiter, they chip off
dust fragments that go into orbit around the planet, forming its ring system.
Copyright 2010, Professor Kenneth R. Lang, Tufts University