Astronomy
Saturn, observed through a telescope, is an incredible and beautiful sight that fires imagination, evoking a sense of space and time and giving an appreciation of universe and the diversity of our solar system.
Saturn is the sixth planet from the Sun and the second largest in the solar system
with an equatorial diameter of 119,300 kilometres (74,130 miles). At more than 888 million miles from the Sun, Saturn
completes an orbit (a Saturnian year) every 29.46 years. It is 95 times more massive than Earth, and is a gas giant
primarily composed of hydrogen with some helium and methane. It is the only planet in the solar system that is less dense
than water (about 30% less). Saturn’s poles are visibly flattened due to a very fast rotation of the planetary axis with its
day of 10 hours and 39 minutes.
Saturn's most famous feature, its rings, were discovered in 1610 by Galileo and
contribute to the planet being one of the most amazing objects in our skies. The rings are classified by letter, divided
into different bands each of differing brightness. Outermost is the A ring, observed clearly through a telescope along with
the middle and brightest B ring. Between the two there is a gap named Cassini`s Division (named after a 17th century
astronomer who observed the planet) with a width equal to the Atlantic Ocean. Closer to the planet, the C ring is fainter,
and only under certain conditions can the other rings be seen. When the Pioneer 11 spacecraft flew by Saturn in 1979, it
revealed that Saturn's rings are composed of thousands of small ringlets, each circling the planet. The rings measure
270,000 kilometres (170,000 miles) from side to side, more than twice the width of the planet, but are no more than a couple
of hundred metres thick.
Saturn has numerous (30+) small satellites, mostly composed of ice and rock, orbiting
it and one large moon with a magnitude of 8 named Titan. At 5,150 kilometres in diameter, and larger than Mercury, Titan is
the second largest moon in the solar system (after Jupiter’s Ganymede) and has a nitrogen atmosphere with traces of other
gases. It is the only known moon to have a thick atmosphere; composed mainly of nitrogen with some methane, which give it
an orange appearance. Because its surface temperature is about –182ºC, methane may be present in the form of snow, rain,
ice and vapour as water is on Earth. Titan is visible in small telescopes orbiting outside of the ring system at 1.22
million kilometres from Saturn. Each orbit of Titan takes 15.9 days.
Saturn has three 10th magnitude moons, Tethys, Dione and Rhea and an oddity Iapetus.
Iapetus is Saturn`s third largest moon with a diameter of 1,400 kilometres. It is 10th magnitude when it lies west of
Saturn and a paler 12th magnitude when it lies to the east showing the opposite hemisphere. On December 31st 2004, NASA`s
Cassini spacecraft flew past Iapetus taking photographs that highlighted strange topographical features. One of these
features is a long narrow ridge (1,300 kilometres long and 20 kilometres high – approximately three times the height of
Mount Everest) that lies almost exactly on the equator. This feature has contributed to a notion held by a few that
Iapetus is an artificial moon. The Cassini spacecraft will next encounter Iapetus during September 2007 with a mission that
includes taking higher resolution photographs and determining whether Iapetus has been volcanically active.
Saturn crossed the equator into the northern hemisphere in 1996 where it will remain
until 2010 with the southern side of the ring system facing the Earth. Because of its distance, its brightness varies little
between opposition and conjunction but is affected by the huge ring system. Seen edge on the rings contribute little or no
light.
Every 15 years the plane of Saturn's rings passes through the Sun, illuminating first
the north and then the south side. For a few days the rings are edge on to the Sun. About the same time the Earth passes
through the ring plane and, depending on the Earth's position, this may happen just once or 3 times. During 1995/96 there
was a triple crossing and the next will be 2038/39. The next single crossings will be in 2009 and 2025.
Mythology
In Roman mythology, Saturn was initially a god of agriculture. Later he became associated with the Greek god Cronus who was dethroned by his son Jupiter. Saturn fathered Neptune, god of the sea, and Pluto, god of the underworld.
Astrology
In terms of astrology, Saturn is the planet of responsibility, self-control and maturity. Expressed in its positive form, Saturn instils self-discipline, patience, trustworthiness, integrity and the sense of responsibility and fortitude to overcome obstacles and hardship. In its negative form Saturn's influence results in reckless ambition, selfishness, pessimism, inflexibility, close-mindedness and even cruelty.
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