Astronomyobservation and study of the planets, stars, galaxies, and other visible and invisible objects found in space. Astronomy is one of humanity's oldest science. It dates to well before the time of recorded history.
The early astronomers were the traders and sailors who depended on the stars to guide them at night. They were the farmers who knew by the rising and setting of certain constellations that planting time, flooding time, or harvesting time were near. They were also the ancient civilizations who built such places as Stonehenge and the native North American medicine wheels for unknown but probably sacred reasons, and needed precise knowledge of the phases of the moon, the northernmost and southernmost seasonal points of the sun, and other information for their purposes. Other observers believed the future could be predicted by where the planets were in the sky when a person was born. Even though the study of stars and planets for this reason is not usually thought of as a science today, these astrologers kept careful records of their observations. These observations were of great importance to astronomers in the past two centuries in trying to make sense of the universe.
Not only is astronomy a very old science, it is also one that can be practiced today with no special equipment, or very inexpensive equipment. Amateur astronomers have contributed a lot of new and useful information, usually about new asteroids or comets, but sometimes about events such as the births or deaths of stars. While some astronomy research does take a great deal of money, such as a project like the Hubble Space Telescope, good astronomy can be done with a simple pair of binoculars.
For the new astronomer, the best tool is, in fact, just a pair of binoculars. Many new astronomers buy expensive or poorly made telescopes, but do not know how to use them, do not know what they are looking at, and soon become frustrated and go on to another hobby. Astronomy is like mountain climbing âÀÔ it is best to start with foothills before challenging Mount Everest. Successful amateurs will buy books or charts showing the constellations and the important stars they contain. They will take time to learn and understand the motions of the Earth, the moon, and the planets. They will spend some time working and learning with only their eyes and a simple recording tool such as a notebook. Binoculars are an excellent tool for a beginner, because they are not expensive, they do not need to be set up or taken down, they are easy to use, and they let the user see interesting things such as the moon's craters, double stars, star clusters such as the Pleiades, and the moons of other planets. They are even better than telescopes for looking at things such as the closer galaxies or very bright comets. When an amateur astronomer has taken some time to learn and understand the night sky, then it is time to buy a telescope.
Astronomy has become a very large science in the past few hundred years, and has many branches. Lunar astronomers study only the moon, while planetary astronomers focus their attention on the planets of the sun, but also the planets discovered around other suns. Some astronomers specialize in particular types of stars, such as binary stars or pulsars. Others study only distant galaxies. There are also astronomers who never look at the sky at all. These theoretical astronomers use the laws of physics and mathematics in combination with [[computers to create models of how the universe behaves, then they compare their models to what is observed. Their goal is to understand and predict the events which happen in the universe.
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