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 know2. Saturn is hidden by clouds of ___________________________________. Page 3053. Saturn has weaker _________________________ so it has thicker clouds. Page 3054. Saturn’s atmosphere has less ______________ than Jupiter has. Page 3035. The equatorial winds on Saturn can reach about _____________ kph. Page 3056. Saturn gives off almost _______ as much energy as it takes in from the Sun. Page 3077. Jupiter’s excess energy is from what was left over from its creation. The excess energy of Saturn is from ______________________________. Page 3088. 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 31010. The largest gap in the rings is called the ___________________________. Page 31311. 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 31412. Saturn has one large moon, and it is called ________________________. Page 31513. Titan is probably a rocky core, surrounded by _________________. The atmosphere is probably mostly ______________________. Page 31714. Saturn’s gravity is so strong, that the nearest five “medium” moons are all ______________________ with Jupiter. So only the faces face the planet. Page 31915. 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 know2. Saturn is hidden by clouds of ____Ammonia Ice___________. Page 3053. Saturn has weaker __Gravity__ so it has thicker clouds. Page 3054. Saturn’s atmosphere has less __Helium__ than Jupiter has. Page 3035. The equatorial winds on Saturn can reach about _1500__ kph. Page 3056. Saturn gives off almost _3X__ as much energy as it takes in from the Sun. Page 3077. Jupiter’s excess energy is from what was left over from its creation. The excess energy of Saturn is from _Helium Rain_. Page 3088. 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 31010. The largest gap in the rings is called the __Cassini divisino___. Page 31311. 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 31412. Saturn has one large moon, and it is called _Titan__. Page 31513. Titan is probably a rocky core, surrounded by _Water Ice__. The atmosphere is probably mostly _Nitrogen and Argon__. Page 31714. 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 31915. 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.