Transcript Saturn - LPS.org

Saturn gives off about 3x more energy than it gains from the
Sun. This is probably because of Helium rain.
Saturn gives off about 3x more energy than it gains from the
Sun. This is probably because of Helium rain.
a. It could be the friction of the rain falling through the planet
Saturn gives off about 3x more energy than it gains from the
Sun. This is probably because of Helium rain.
a.It could be the friction of the rain falling through the planet
b.It could be the condensation of Helium gas. (this is the one
that I prefer).
Shepherd moons
tend to work together,
and hold the edges of
the rings “tight” by
gravitational
deflection.
The moons also
“trade places” by
their gravitational
attraction to each
other.
Titan,
(less
massive, but
larger than
Mercury) is
smoggy.
The Cassini–Huygens spacecraft was launched on October 15, 1997. Huygens
separated from the Cassini orbiter on December 25, 2004, and landed on Titan on
January 14, 2005 . It touched down on land, but it could have touched down in an
ocean. The probe was designed to gather data for a few hours in the atmosphere,
and possibly a short time at the surface. It continued to send data for about 90
minutes after touchdown. It remains the most distant landing of any craft launched
from Earth.
Saturn Questions
1. Saturn is best known for its _____________________________________. You know
2. Saturn is hidden by clouds of ___________________________________. Page 305
3. Saturn has weaker _________________________ so it has thicker clouds. Page 305
4. Saturn’s atmosphere has less ______________ than Jupiter has. Page 303
5. The equatorial winds on Saturn can reach about _____________ kph. Page 305
6. Saturn gives off almost _______ as much energy as it takes in from the Sun. Page 307
7. Jupiter’s excess energy is from what was left over from its creation. The excess energy of Saturn is from
______________________________. Page 308
8. The rings are probably made of small rocks and ______________. This is an inference, because they have an albedo
(amount of reflection) of about _______%.
9. Ring material may come from ripped up moons. The point where the gravitational pull of Saturn equals the structural
integrity of the moon itself is the _______________
_________________. This is also called the tidal stability limit. Page 310
10. The largest gap in the rings is called the ___________________________. Page 313
11. Two small moons, called Prometheus and ______________, act as shepherds. They “guide” particles in the “f” ring, and
keep it small and compact. Together they are called the ______________________________. Page 314
12. Saturn has one large moon, and it is called ________________________. Page 315
13. Titan is probably a rocky core, surrounded by _________________. The atmosphere is probably mostly
______________________. Page 317
14. Saturn’s gravity is so strong, that the nearest five “medium” moons are all ______________________ with Jupiter. So
only the faces face the planet. Page 319
15. Two small moons _____________________ and __________________ share the same orbit, and play a game of
celestial tag.
16. Most of the moons are probably made entirely of __________. But at these low temperatures, it would be as hard as a
rock. Craters would form. Page 315
Saturn Questions
1. Saturn is best known for its ___Rigngs___. You know
2. Saturn is hidden by clouds of ____Ammonia Ice___________. Page 305
3. Saturn has weaker __Gravity__ so it has thicker clouds. Page 305
4. Saturn’s atmosphere has less __Helium__ than Jupiter has. Page 303
5. The equatorial winds on Saturn can reach about _1500__ kph. Page 305
6. Saturn gives off almost _3X__ as much energy as it takes in from the Sun. Page 307
7. Jupiter’s excess energy is from what was left over from its creation. The excess energy of Saturn is from _Helium Rain_.
Page 308
8. The rings are probably made of small rocks and _Ice__. This is an inference, because they have an albedo (amount of
reflection) of about _80__%.
9. Ring material may come from ripped up moons. The point where the gravitational pull of Saturn equals the structural
integrity of the moon itself is the _Roche limit__
_________________. This is also called the tidal stability limit. Page 310
10. The largest gap in the rings is called the __Cassini divisino___. Page 313
11. Two small moons, called Prometheus and __Pandora_, act as shepherds. They “guide” particles in the “f” ring, and keep
it small and compact. Together they are called the __shephard sttelites__. Page 314
12. Saturn has one large moon, and it is called _Titan__. Page 315
13. Titan is probably a rocky core, surrounded by _Water Ice__. The atmosphere is probably mostly _Nitrogen and
Argon__. Page 317
14. Saturn’s gravity is so strong, that the nearest five “medium” moons are all _tidally locked___ with Jupiter. So only the
faces face the planet. Page 319
15. Two small moons _Hyperion _ and _Phobe__ share the same orbit, and play a game of celestial tag.
16. Most of the moons are probably made entirely of Water Ice__. But at these low temperatures, it would be as hard as a
rock. Craters would form. Page 315
Uranus
Oh, you know how to pronounce
it!!
The prior image shows the planet Uranus, the first planet
discovered in modern times. It was found accidentally by
William Herschel while he was searching the sky with a
telescope in 1781. It had actually been seen many times before
but dismissed as a star.
Uranus is largely hydrogen and helium, but (like Neptune)
contains higher proportions of heavy elements than Jupiter or
Saturn, and is covered with clouds. Our only direct spacecraft
observation of Uranus came from Voyager 2 in 1986.
Uranus is the 3rd of the Gas Giant planets, and the first planet
discovered in "modern" times (1781). It is barely visible from the
Earth without a telescope, which explains why it was not known
as a planet to the ancients, and why it had been observed various
times after the telescope had been invented without the
observers realizing that it was a planet and not a star.
Documented sitings go back to at least 1690 when Flamsteed
catalogued it as a star.
The density is about 1.2 g/cc, implying that it is mostly hydrogen and helium.
The mass is about 15 times that of the Earth, which makes it the 4th most
massive planet. But its radius of about 4 times that of the Earth makes it the
3rd largest planet, since Neptune has a smaller radius but larger mass
(because Neptune's density is higher). The rotation axis is unusual in that it
lies only 8 degrees out of the plane of the orbit. Thus, at times the rings and
the orbits of the moons appear like a "bulls-eye" when viewed from the
Earth. The average rotational period is a little over 17 hours, and its orbital
period is 84 years, at a mean separation of 19.2 A. U. from the Sun.
The rings are less extensive than those of Saturn, and may be rock rather
than ice. There are 5 large moons and 10 small ones.
Uranus has a relatively featureless appearance at visible wavelengths. Even
from Voyager 2 at a distance of 80,000 km there were few distinguishable
features. This is believed to be due to Uranus being further from the Sun
than Jupiter and Saturn, which means its temperature is lower (only 58
degrees Kelvin in the upper atmosphere). This decreases the likelihood of
chemical reactions making the colorful compounds that give the surface
features on Jupiter and Saturn. In addition, the upper atmosphere is thought
to have a high-level petrochemical haze that obscures features lower in the
atmosphere.
The blue color is because
of methane gas in the
atmosphere, which
absorbs red and orange
light strongly, leaving
more blue light to be
scattered to the observer.
The clouds are thought to
be mostly methane ice,
with a temperature at
the cloud tops of about 221 degrees Celsius.
Voyager 2 confirmed the suspicion that
Uranus had a magnetic field. The field is
about 50 times stronger than that of the
Earth and is tilted about 60 degrees with
respect to the rotation axis. As a result, the
magnetic field moves like a corkscrew as
Uranus rotates, as illustrated in the following
movie (5 MB). One hypothesis for this
behavior of the magnetic field is that it
originates in a thin conducting shell outside
the core of the planet rather than deep in
the core as for the Earth or Jupiter. The
pressure would not be high enough for the
relevant conducting material to be metallic
hydrogen. A mixture of water, methane, and
ammonia under sufficient pressure could
provide the requisite electrical conductor.
The magnetosphere contains belts of charged particles similar to those of the Earth. The
rings and most of the moons orbit within the magnetosphere and thus are protected
from the Solar wind.
The rings of Uranus (and some of its
moons) are shown in the adjacent
Hubble Space Telescope image. The
rings were discovered from the Earth
in 1977 when Uranus occulted (passed
in front of) a star and it was noticed
that there were dips in the brightness
of the star before and after it passed
behind the body of Uranus.
This data suggested that Uranus was
surrounded by at least 5 rings. Four
more rings were suggested by
subsequent occultation measurements
from the Earth, and 2 additional ones
were found by Voyager 2, bringing the
total to 11 (the adjacent image shows
only some of the brighter rings.
Most of the rings are not quite circular, and most
are not exactly in the plane of the equator. The
rings vary in brightness with angle around the
moon, apparently because they vary in width with
angle. The rings are very narrow (some only a few
kilometers across) and no material can be
detected in the regions between the rings. It is
speculated that this stability of the narrow rings
may be due to small "shepherding satellites", as
discussed in conjunction with Saturn's rings.
The brightest ring is termed the
Epsilon ring. Voyager 2 found two
small shepherd moons for it, one
just inside and one just outside
(adjacent image (Ref); the white
dots inside the yellow circles). They
appear to be about 20-30 km in
diameter, and have been named
Ophelia and Cordelia.
It is not clear why Miranda has been so
active geologically. Some theories
invoke tidal heating effects earlier in
its history, or a collision that tore it
apart and allowed it to coalesce again.
None are very conclusive.