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All About Astronomy: Definition and Meaning

written by: Darlene Zagata•edited by: RC Davison•updated: 7/29/2010

Astronomy is the study of celestial objects in the universe. It is a natural science that is concerned with the physics, chemistry, motion and evolution of such objects as well as the universe itself. Astronomy is considered the oldest science.

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    A Description Of Astronomy

    600px-Deepest View Ever of the Universe You now know that astronomy is the scientific study of the Universe but what does that mean exactly? Astronomy means - "law of the stars" in Greek. It is the science that searches for objects such as stars and planets and seeks to understand their origin, evolution, composition and movements. Astronomy uses many other disciplines such as physics, mathematics and chemistry in the study of the Universe in order to understand the composition of these objects, and their location in the cosmos.

    Astronomy has evolved just as the Universe continues to evolve. Although amateur astronomers may still gaze at the night sky through a telescope in their backyards, there are observatories that use sophisticated equipment to study the Universe, and its many celestial objects. Long ago, astronomers could only observe objects that were visible to the naked eye. Now, through technological advancements they can observe distant parts of the universe and a vast array of objects.

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    Early astronomers mapped the position of the planets and stars that they could observe with the naked eye. Long ago, people developed calendars by studying the heavens, and sailors navigated the seas by the stars. The Earth was believed to be the center of the Universe. It wasn't until the Renaissance period that the idea of the Earth revolving around the Sun began to grow in popularity. Early astronomy was mostly theory, but the invention of the telescope opened a new doorway for astronomy, and the science has continued to evolve throughout its history.

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    Branches of Astronomy

    481px-Whirpool Galaxy Modern astronomy has branched out into specific fields and subfields of study such as celestial mechanics, stellar astronomy, cosmology and theoretical astronomy to name a few. These different fields define the various aspects and goals of the overall science of astronomy.

    • Celestial mechanics measures the positions of celestial objects.
    • Stellar astronomy studies stars and their evolution.
    • Cosmology is the study of the universe as a whole.
    • Theoretical astronomy uses analytical models and simulations to gain better insight into the workings of the universe.

    All of the various branches of astronomy are important in obtaining knowledge of the cosmos.

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    Discoveries and Discoverers in Astronomy

    There have been many significant contributions in the field of astronomy, each propelling the science forward with new awe and understanding.

    • Nicolas Copernicus developed a heliocentric model of the Universe that explained the retrograde motion of the planets. Simply put, the notion that the Earth revolves around the Sun rather than the opposite.
    • Galileo Galilei observed craters and mountains on the Moon, the four largest satellites of Jupiter and the phases of Venus.
    • Johannes Kepler established the three laws of planetary motion.
    • Giovanni Cassini discovered four satellites of Saturn and the gap in Saturn's rings now known as "Cassini's Division."
    • Sir Issac Newton developed the theory of gravity.
    • William Herschel discovered several celestial objects including Uranus and two of its moons.

    The list goes on and discoveries continue to be made. After all, the Universe is a very large place with much to learn through the fascinating science of astronomy.

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    Ghana Science Project: What is Astronomy?

    What is Astronomy?

    Guide to Space: What is Astronomy?

    The Astro Pages: What is Astronomy?

    Famous Astronomers and Astrophysicists

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