The Solar System formed 4. 6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority of the system’s mass is in the Sun, with the majority of the remaining mass contained in Jupiter. The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being primarily composed of rock and metal. The four outer planets are giant planets, being substantially more massive than the terrestrials. The two largest, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called volatiles, such as water, ammonia and methane. All eight planets have almost circular orbits that lie within a nearly flat disc called the ecliptic.
The need to comprehend and explain our origins--the world of natural phenomena--cannot be properly viewed as exclusively scientific. Instead, it should be viewed as something generally human. Through enchanting, magical narratives involving super-human heroes and heroines, as well as anthropomorphic gods and goddesses, ancient pre-scientific societies attempted to explain and make some order out of the mysterious complexities of the Cosmos. Earth's Moon has always held a place of special fascination for our species, inspiring our human imagination to escape its troubling limitations and--as we search beyond our Earthbound lives--help us to move towards an understanding of who we are, in all our human complexity. Therefore, ancient gods and goddesses mimic our bewitching Moon's unending, gentle tug on the forces of life. In this sense, it may be detrimental to completely dismiss these ancient myths--ascribing them to an unsophisticated and archaic past.
In the Eastern world, such as in China and India, the moon is actually the primary consideration in studies of astrology. The moon signs and cycles are used to determine the best time for activities, and is a part of daily life. This may seem backward to some, but actually results in more accurate predictions in many cases than Western astrology can ascertain.
After a long and dangerous journey through the space between planets, the Cassini/Huygens Spacecraft reached Saturn on July 1, 2004. On December 25, 2004, the Huygens Probe was purposely liberated from the Cassini Orbiter. Huygens then began its historic descent through the dense blanket of golden-orange fog to at last lift the veil hiding Titan's long-hidden face.