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Jupiter
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Jupiter is the fifth planet from the Sun and the largest planet within the Solar
System. It is a gas giant with mass one-thousandth that 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. 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.
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Atmosphere
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99% Hydrogen & Helium
1% Methane, Ammonia, Hydrogen sulfide, Water |
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Climate Change On Jupiter
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A popular argument against anthropogenic global warming is that other planets in
the solar system are warming (Fred Thompson even seems to be making it one of
his campaign policies). Last week, I received an intriguing email from John
Cross speculating that perhaps Jupiter's climate change were the effects of the
Shoemaker-Levy 9 comet collision. None of the papers on the topic seemed to
indicate any long term effects from the comet impact but scratching around the
peer reviewed literature did dig up some interesting facts about Jupiter's
climate. Between 1998 and 2000, three White Ovals (giant vortices) on Jupiter
merged and formed a new oval, approximately the size of Earth. Initially, it was
white but turned brown and then red in 2005. The official name of the red spot
is "Oval BA" although it's more popular nickname "Red Spot Jr" has considerably
more cachet.
What fuels Jupiter's storms?
On Jupiter, the sun's energy is only 4% of the level we receive on earth,
nowhere near enough to fuel its turbulent, planet-sized storms. Jupiter radiates
into space almost twice the heat it absorbs from the sun. This internal heat
source, via moist convection, converts heat flow into the kinetic energy that
fuels Jovian storms (Ingersoll 2000, Gierasch 2000).
How is Jupiter's climate changing?
Temperature is relatively uniform on Jupiter - the temperature at the poles is
nearly the same as at the equator. This is due to the chaotic mixing of heat and
airflow from vortices (eg - the White Ovals). The oscillatory motions of the
White Ovals ceased after they merged, dampening the movement of heat from
Jupiter's equator to its south pole. The latitudes near 34°S, the same latitude
where Red Spot Junior is located, are predicted to become barriers preventing
the mixing of heat and airflow. If so, Jupiter's equatorial regions will become
warmer and its poles will become cooler. Average temperature at some latitudes
could change by as much as 5.5° Celsius (Marcus 2006).
Implications for Earth's climate
While Jupiter's storms are fueled from an internal heat source, Earth's climate
gets its energy from the sun (which hasn't shown any long term warming trend for
over 50 years). Additionally, Jupiter's climate change is due to shifts in
internal turbulence rather than an external forcing. So what is the connection
between Jupiter's climate change and Earth's global warming?
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