Information AboutPlanet |
| CATEGORIES ABOUT PLANET | |
| planets | |
|
A planet, as Defined by the International Astronomical Union (IAU), is a celestial body Orbit ing a Star or Stellar Remnant that is massive enough to be rounded by its own Gravity , not massive enough to cause Thermonuclear Fusion in its core, and has Cleared Its Neighbouring Region of Planetesimals . The term ''planet'' is an ancient one, with ties to history, science, myth and religion. The planets were originally seen as a divine presence; as emissaries of the gods. As scientific knowledge improved, the human perception of the planets changed over time, incorporating A Number Of Disperate Objects . Even now there is no unconstested definition of what a planet is. In 2006, the IAU officially adopted a resolution Defining Planets within the Solar System . This definition has been both praised and criticised, and remains disputed by some scientists. When astronomers first gazed up at these strange objects that moved through the night sky, they noted that they appeared to Orbit the Earth in circular motions. With the development of the telescope, the planets, which now included Earth, were found to orbit the Sun, and rather than circular motions, their orbits were elliptical. As observational tools improved, astronomers saw that, like Earth, the planets rotated around tilted axes and shared such features as ice-caps and seasons. Since the dawn of the Space Age , probes have been sent to every planet in the Solar System , and the discoveries they have made have shifted Planetary Science from the realm of astronomy to the realms of Geography and Geology . The planets have been found to share characteristics such as volcanism, hurricanes, tectonics and even hydrology, previously only known on Earth. Since 1992, and the discovery of hundreds of Extrasolar Planets , scientists are beginning to observe similar features across the galaxy. Under IAU definitions, there are eight planets in the Solar System (s and smaller, rocky Terrestrials . Dwarf planets, a separate category, can either be terrestrials or frozen Ice Dwarf s. ETYMOLOGY , after whom the Solar System's planets are named]] In ancient times, astronomers noted how certain lights moved across the sky in relation to the other stars. The lights were first called "πλανήται" (''planētai''),See Romanization Of Greek for the transcription scheme. meaning "wanderers", by the ancient Greeks, and it is from this that the word "planet" was derived.23 The Greeks gave the planets names: the farthest was called ''Phainon'', the shiner, while below it was ''Phaethon'', the bright one. The red planet was known as ''Pyroeis'', "fiery", while the brightest was known as ''Phosphoros'', the light bringer, and the fleeting final planet was called ''Stilbon'', the gleamer. However, the Greeks also made each planet sacred to one of their pantheon of gods, the , the Titan who fathered the Olympians, while Phaethon was sacred to Zeus , his son who deposed him as king. Ares , son of Zeus and god of war, was given dominion over Pyroeis, while Aphrodite , goddess of love, ruled over bright Phosphoros, and Hermes ruled over Stilbon.4 The Greek practice of grafting of their gods' names onto the planets was almost certainly borrowed from the Babylonians , a contemporary civilisation in what is now Iraq , from whom they had begun to absorb astronomical learning, including constellations and the zodiac, by 600 BCE.5 The Babylonians had in turn inherited the practice from their predecessors, the Sumerians , who flourished around 2500 years before. The Babylonians named Phosphoros after their goddess of love, Ishtar, Pyroeis after their god of war, Nergal, and Phaethon after their chief god, Marduk.6 There are too many concordances between Greek and Babylonian naming conventions for them to have arisen separately. There does, however, appear to have been some confusion in translation. For instance, the Babylonian Nergal was a god of war, and the Greeks, seeing this aspect of Nergal's persona, identified him with Ares , their god of war. However, Nergal, unlike Ares, was also a god of the dead and a god of pestilence. Today, most people in the western world know the planets by names derived from the Olympian Pantheon of gods; however, because of the influence of the Roman Empire and, later, the Catholic Church , they are known by their Roman (or Latin) names, rather than the Greek. The Romans, who, like the Greeks, were Indo-Europeans , shared with them a Common Pantheon under different names but lacked the rich narrative traditions that Greek poetic culture had given Their Gods . During the later period of the Roman Republic , Roman writers borrowed much of the Greek narratives and applied them to their own pantheon, to the point where they became virtually indistinguishable.7 When the Romans studied Greek astronomy, they gave the planets their own gods' names.
|
|
|