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Jupiter
Jupiter
Interesting note…at least to me!
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The ancient Greeks did not know how big
Jupiter was…and Venus appeared brighter.
So why did they name it after the most
powerful god?
When and where can you see it?
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Fourth brightest object in the sky (behind
the Sun, moon, and Venus).
Physical Properties
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Mass: 1.9 x 1027 kg or 318 Earth masses.
Has more than twice the mass of all the
other planets combined.
Still, it is only a 1000th the mass of the Sun.
Its radius is 11.2 Earth radii. More than
1400 Earth’s would fit inside!
It orbits 5.20 AU’s from the sun.
Has no orbital tilt, therefore no seasons.
Rotation Rates
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Jupiter experiences differential rotation.
Because it is gaseous, not all parts orbit at
the same rate!
Rate of rotation: 9 hours, 55 min
Spinning this fast gives is an equatorial
bulge.
Rate of revolution: 11.9 Earth years
Atmosphere
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Is dominated by atmospheric bands and
the Great Red Spot.
The bands are areas of low pressure or
high pressure.
The colors are based on complex chemical
reactions occurring in the bands.
Some simple organic molecules (ethane)
have been detected in the clouds.
What is beneath the clouds?
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Well, more gases. This would be
considered to be the interior of the planet.
Temperature and density increases with
depth.
Eventually the gas becomes a liquid.
Further down this liquid hydrogen becomes
metallic!
Finally, there is a small extremely dense
solid core (may contain between 5-20 Earth
masses.)
Weather on Jupiter
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The Great Red Spot averages twice the
diameter of Earth.
Flashes resembling lightning have been
detected.
White ovals depict storm systems.
Brown ovals depict holes in the clouds that
allow for looks down into the lower
atmosphere.
Reading on pg. 284
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Almost a star?
Jupiter’s Magnetosphere
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Jupiter has a huge magnetosphere that
extends all the way out to Saturn!
This results in aurorae.
Jupiter as a heat source
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Jupiter gives off more heat itself than it
receives from the sun.
Why?
Some is due to radioactive decay, just as in
the Earth.
However, most is residual heat from its
formation.
Moons of Jupiter
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The current count is 63.
The largest 16 are 10 km or bigger.
The four largest, the Galilean satellites are
Io, Europa, Ganymede and Callisto, are
named after the mythological attendants of
Jupiter.
Some are locked in synchronous orbit with
Jupiter, due to tidal forces.
Moons of Jupiter, cont.
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Some of the smaller moons orbit very
eccentrically.
Some revolve in a retrograde direction.
These smaller ones may have at one time
been part of a larger object that broke apart
after being captured by Jupiter’s gravity.
Another interesting point (to me)!
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The orbital periods of the four Galilean
satellites are in the ratio of 1:2:4:8.
Io: Land of Volcanoes
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Very dense
Geologically active - due to tidal forces from
Jupiter and the other Galilean satellites.
More than 80 active volcanoes have been
discovered.
The largest one is Loki – larger than the state of
Maryland and emits more energy than all of
Earth’s volcanoes combined.
It’s mass and radius are similar to Earth’s moon.
Europa: Land of Ice
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Contains few craters.
Is likely covered by an ocean that is frozen
over.
This water could possibly harbor life
(marine).
Ganymede and Callisto: Twins?
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Ganymede is the largest moon in the solar system
(bigger than Pluto and Mercury).
Ganymede has maria.
Ganymede used to have plate tectonics.
Callisto is home to a large basin called Valhalla.
Callisto shows no evidence of plate tectonics.
It may have a layer of slush ice beneath its
surface.
Jupiter’s Ring
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Discovered by Voyager in 1979.
Very small.
Could be a result of meteoric impact on two
of Jupiter’s small moons.