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NATURAL SATELLITES |
| The majority of the planets in our solar system have natural satellites, also referred to as moons. Mercury and Venus, the two planets closest to the Sun, are the only planets which to this day have no known satellites. |
EARTH'S moon is large. Its moon orbits 384,440 km from Earth and is 3,476 km in diameter with a mass of 7.35e22 kg; however, many of us may not be aware that the moon we gaze upon may not be the only natural satellite that our Earth possesses. In 1986 Cruithne was discovered and is now known as Earth's second satellite. Cruithne takes a horseshoe path around our planet and is thrown about by the Earth's and Moon's gravity. In a more recent discovery, in September 2002, an amateur astronomer observed an unknown object from his Arizona observatory. Bill Yeung, believed he may have come upon another moon. This moon was designated J002E3 after he contacted the Minor Planet Center in Massachusetts. Controversy surrounds this discovery. Experts are not sure what this object is, and speculations are that this “moon,” is perhaps nothing more than space junk. If experts conclude that Yeung's discovery does in fact have characteristics of a moon then it will be known as Earth's third satellite. |
| Our neighbor MARS has two minor satellites. Minor satellites are small moons that are actually chunks of rock that orbit a planet. Phobos and Deimos are Mars's moons. Phobos is 27 km long in its longest dimension and Deimos is 15km long in its longest dimension. Unlike the Earth's moon, these moons were formed differently. They are more than likely fragments that broke off a much larger object during a collision. These fragments are then captured by the planets gravitation. Mars is not the only planet to have such satellites. |
| Oh so many moons. There are now 57 moons that have been discovered to float around JUPITER. Its largest and most talked about moons are known as the Galilean satellites. Ganymede, Callisto, Europa, and Io were named so because they were the only four moons that were visible to Galileo. |
Ganymede could be considered as planet, if it were bounded to Jupiter that is. Ganymede is larger than |
| Callisto is the outermost Galilean moon. It is almost Mercury's twin in size and appearance. This moon has no distinct characteristics aside from the craters that cover every square mile or so. |
| Europa is closer to Jupiter. It is the smoothest natural body in the solar system and when viewed closely has dark, deep narrow cracks. Geologists speculate that Europa may have liquid underneath its icy surface. And where there is water....there may be life! |
| Io has volcanoes that make it the most active in the solar system. These volcanoes burst with sulfuric acid which contribute to Io's many colors. They also make Io one of three moons to have an atmosphere in the solar system. Saturn's Titan and Neptune's Triton are the other two. |
| The following are some of Jupiter's other moons: Metis, Adrastea, Amalthea (the largest non-Galilean moon at 262 km wide in diameter), Thebe, Themisto, Leda, Himalia, Lysithea, Elara, Ananke, Carme, Pasiphae and Sinope. |
| SATURN has many moons as well, 48 natural satellites to date. Titan, although, is its largest at 5,140 km in diameter, meaning Titan is bigger than our Earth's moon. Titan was discovered in 1655 by C. Huygens and has its own thick atmosphere. All of Saturn's 48 moons are as follows: Aegir, Albiorix, Atlas, Bebhionn, Bergelmir, Bestla, Calypso, Daphnis, Dione, Enceladus, Epimetheaus, Erriapo, Farbauti, Fenrir, Fornjot, Hati, Helene, Hyperion, Hyrokkin, Iapetus, Ijirag, Janus, Kari, Kiviug, Loge, Methone, Mimas, Mundilfari, Narvi, Paaliag, Pallene, Pan, Pandora, Phoebe, Polydeuces, Prometheus, Rhea, Siarnag, Skadi, Skoll, Surtur, Suttung, Tarvos, Telesto, Thethys, Thrym, Titan and Ymir. |
| Although that list was long, astronomers are still finding more moons that Saturn may have. |
| Still a lot of moons, but not as many as Jupiter or Saturn, URANUS possesses 27 known satellites. Titania is its largest moon at about have the size of our Earth's moon. Uranus's moons are mostly composed of ice and rock. Its remaining 26 moons are: Miranda, Ariel, Umbriel,Oberon, Cordelia, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Cupid, Belinda, Puck, Mab, Caliban, Stephano, Sycorax, Margaret, Prospero, Setebos, Trinculo, S/1986U10, S/2001U2, and S/2001U3. A lot of these moons seem to be minor satellites due to their size and orbit. They also appear to be normal with the exception of Miranda and Ariel who may have had violent past. |
| NEPTUNE has seven small moons and Triton makes eight. Triton is 2,700 km wide in diameter and was the first discovered by Lassell in 1846. Naiad, Thalassa, Despina, Galatea, Larissa, Proteus and Nereid are the smaller moons. |
| Charon is PLUTO'S most famous moon. This moon has people wondering if whether or not it may be a dwarf planet. Charon's diameter is about 1,207 km in diameter and is just over half the size of its planet, Pluto. Unlike Pluto, which is covered by nitrogen and methane ices, Charon has a surface that appears to be dominated by a less volatile water ice and also appears to have no atmosphere. Pluto and Charon are gravitationally locked; therefore, they keep the same face towards each other. Pluto has two less talked about moons named Hydra and Nix. Their discovery was announced in October 2005. Hydra orbits Pluto at a distance of 65,000 km, taking about 38 days to complete an orbit. The sizes of the two moons are not yet known, although, they are expected to be no smaller than 44 km in diameter and no larger than 130 km, with Nix thought to be the smaller of the two. Nix orbits at a distance of an estimated 42,000 km. Taking almost 25 days to complete an orbit. |
| Big or small. Many or none. One thing is to be said about a planet's natural satellite and that is they are beautiful sights. |
RINGS
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| Saturn, Jupiter, Uranus, and Neptune all share an interesting and beautiful characteristic, they all have rings in their orbit. |
| SATURN'S ring's were discovered by Galileo in 1610. Galileo was fascinated by his new discovery which he first thought was a triple-bodied star. He later became perplexed by the disappearance of the rings two years after he first gaze upon them; however, they were not gone, just not visible. What Galileo did not know was that the Earth had passed through Saturn's ring plane and the rings were edge on and could not be resolved by his 20x telescope. Galileo's discovery did, although, begin the scientific process of solving the mystery we call Saturn's rings. |
| In 1655, Christan Huyges proposed that Saturn was surrounded by a solid ring: “A thin, flat ring, nowhere touching, and inclined to the ecliptic.” Throughout time theories came and went and finally in the mid 1800's it was proposed that the rings were not solid but instead made of small particles. Those small particles are primarily water ice and range from microns to meters in size. |
| Today we know that the rings are actually thousands of individual ringlets and are then divided into five major components: the G, F, A, B, and C rings, listed from the outside in with the newly discovered D ring being closet to the plant. The “Cassini Division” refers to the large gap between Rings A and B which are more broad and visible. Rings F and G are the opposite, being rather thin and difficult to see. The rings show tremendous amount of structure on all scales; some of this structure being related to gravitational perturbations by Saturn's moons; however, it is now nearly 400 years after the rings were discovered and astronomers are still pondering solutions to the unexplained. |
| In 1980,Voyager 1 revealed that Saturn wasn't alone when it came to rings. JUPITER'S faint, dark and narrow rings composed not of water ice like Saturn's, but of tiny rock fragments and dust. These rings are continuously losing material and being resupplied with new dust from mircometeors hitting Metis, Adrastea, Amalthea and Thebe, Jupiter's inner moons. Voyager 2 further investigated these rings bringing back a more complete set images. the rings is now known to be composed of three major components: The Halo Ring is faint and wide, 22,800 wide and about 20,000 km thick. This ring orbits closest to Jupiter and merges from its outer edges to the Main Ring. The Main Ring is about 7,000 km wide and has an abrupt outer boundary at 128,940 km from the center of the planet. The main ring encompasses the orbits of Adrastea and Metis. As we travel just outside the main ring we find a pair of broad and exceedingly faint rings called the Gossomer Rings. One is bounded by the orbit of the moon Amalthea and the other by the orbit of Thebe. Jupiter's rings are not easily visible because they do not reflect much of the light they receive. |
| Everyone knows Saturn has these magnificent rings in its orbit, and many may even know about Jupiter's, but URANUS' and NEPTUNE'S rings are hardly ever mentioned in people other than astronomers. Uranus' nine rings were discovered 1977. When the Voyager returned home with photographs, two new ringlets were visible and measurements of all 11 were then made. Now in 2005 the ring count stands at 13 rings. Uranus' rings are distinctly different from Saturn's and Jupiter's. The outermost epsilon ring is composed mostly of ice boulders several feet across. A very tenuous distribution of fine dust also seems to be spread throughout the ring system. Neptune is circled by a system of very thin, dark rings located in clumps. These rings are are composed of small rocks and dust. They almost circular (unlike Uranus' elliptical ring system). There are three distinct rings, named Adams, Le Verrier and Galle (after the discovers of Neptune) plus a wide plateau of dust adjacent to the Le Verrier ring (this wide sheet of orbiting dust is co-orbital with the moon Galatea). |
| These rings have been very difficult to detect because they are not uniform in thickness and density. The thicker part of the rings are called ring arcs; these are the parts of the rings that are more easily detected. The Adams ring has three prominent arcs (named Liberty, Equality and Fraternity). The gravitational pull of Neptune's moons may cause the unevenness of the rings. |
| Thin, broad, light, dark even unevenness, no matter their physical appearance, these rings continue to be fascinating and breathe taking. |
REFERENCES
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https://bobthealien.com |
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