Transcript astron_ch_13b

Atmosphere:
Jupiter’s atmosphere
has two basic features.
1) Changing parallel
bands aligned with the
equator, and
2) the Great Red Spot.
The Great Red Spot
is an Earth-sized
hurricane that has
been observed for
100’s of years.
Gases:
H2 - 86%
He - 13%
CH4, NH3,
and H2O - <1%
One question to be
answered is whether
chemical reactions
cause the different
colors in the atmosphere
or could it be organic
compounds??
Atmospheric Bands –
bright-colored ZONES upward-moving currents,
high pressure areas.
dark-colored BELTS downward moving currents,
low-pressure areas.
The rapid rotation rate
has caused these bands to
circle the planet. The zones
are slightly higher in the
atmosphere than the belts.
Differences in temperature
causes the differences in
color.
Jupiter also has smallscale weather patterns,
e.g. the Great Red
Spot.
The Great Red Spot is
at least 300 years old.
Its size varies
but is twice the
size of Earth on
the average.
The flow of the gases
in the GRS is
counterclockwise.
It rotates the planet
at a rate similar to the
rotation of the interior.
Photographs of the
dark side of Jupiter
show auroral activity
and flashes that are
probably due to
lightning.
Lightning
Other hurricane type
storms are white
ovals. These rotate
counterclockwise and
are higher in the
atmosphere.
There are also
brown ovals.
These are lower in
the atmosphere and
only occur around
20° north latitude.
Jupiter emits about
twice as much energy
as it receives from
the Sun; therefore,
it must have its own
internal heat source.
It was believed for a short
time that this might be
caused by star-like fusion
at Jupiter’s core. Jupiter
was like a small star. But
this is no longer believed
to be true.
It is believed that this is
the slow escape of
gravitational energy left
over after Jupiter’s
formation. This loss is
very small compared to
the planet’s total energy.
Internal Structure –
The clouds on Jupiter
are less than 200 km
thick. At a depth of a few
thousand km the gas
transitions into a liquid.
At a depth of about
20,000 km hot liquid
hydrogen gas
becomes “metallic”
and is an excellent
conductor.
Jupiter is believed to
have a small, dense
core which is
approximately 15 times
Earth’s mass. It is
probably made up of
“rocky” materials.
The central core
temperature of
Jupiter is about
40,000K!!
Jupiter’s magnetosphere is
30 million km across; 1 million
times larger than Earth’s.
This is far larger than the
entire Sun. The large tail
produced by the solar wind
extends at least as far as
Saturn’s orbit.
In the inner
magnetosphere,
Jupiter’s rapid rotation has
forced most of the charged
particles into a flat current
sheet lying along the
magnetic equator.
Jupiter’s magnetic
field strength is
20,000 times
greater than
Earth’s.