About Astronomy
Astronomy is the scientific study of the universe--its components, its behaviors, its history and its future. Planets, stars, galaxies and everything else in between are its subjects of inquiry.
The study of astronomy gives us essential information about the universe that is used for practical and scientific applications. Discoveries within the field of astronomy have contributed to the fields of navigation, solar radiation, image-processing techniques used in medicine and parallel computing.
History of
The history of astronomy is divided into three periods--the Geocentric period, the Galactic period and the Universal period.
The Geocentric dates back to ancient times and extends all the way to the 16th century. The earth was believed to be the center of the universe, with the sun, the moon and the stars revolving around it. Scientific methodologies were nonexistent during this time, and the purpose of the astronomer was to search the skies for clues to good and evil omens.
The Galactic period ranged from the sixteenth to the nineteenth centuries and is where modern astronomy began. With the invention of the telescope, astronomy entered the realm of the scientific method, albeit on a much larger scale.
The Universal period marks our present stage in the history of astronomy. The existence of many more galaxies than our own has become known. Astronomers now focus on discovering and understanding these unknown worlds in an effort to better understand the complete universe.
Function
The positions and movements of the stars, the sun, the moons and the planets serve as a dynamic map of the universe. The study of astronomy has given us the guidelines for time-keeping and calendar maintenance, both of which underlie the workings of the fields of natural science and physics.
In fact, modern astronomy is so tightly interwoven with the field of physics that astronomers are also identified as astrophysicists. What distinguishes the two disciplines is astronomy focuses on the universe beyond the earth's atmosphere, whereas astrophysics is concerned with the physical processes associated with celestial bodies and space.
Features
The major components of our own Milky Way Galaxy all revolve around a single star, the sun. The sun, while appearing large to us, is similar in size to many other stars that we see in the sky. It appears so large because it is the closest star to our planet.
Other major components of our solar system are plants, planetoids, satellites, comets, meteoroids, stars and nebulae. Planets are large, solid and nearly spherical masses that revolve around the sun in circular orbits.
Planetoids are small, solid bodies of different shapes that revolve about the sun. They're also known as asteroids, or minor planets.
Satellites are the moons, which belong to six of the nine major planets.
Comets are large, solid and uniquely shaped. A comet is made up of a luminous sphere connected to a long tail.
Meteoroids are tiny, small objects that move through space; some of which enter the earth's atmosphere. Once inside the earth's atmosphere, meteoroids disintegrate into dust. We know them as meteors, or shooting stars.
Stars are large globes of hot gas that generate their own light.
Nebulae are large clouds made of dust and gas.
Size
Because the expanse of the universe is so much greater than any measurable distances on earth, astronomers use the unit of a light year when measuring or calculating celestial properties. When measured in miles, a light year equals 5,880,000,000,000 miles.
The length of our galaxy is around 100,000 light years. It's maximum depth is 15,000 light years. The average distance between galaxies is one million light years. In comparison, our sun is only eight light minutes away from the earth which figures out to be 93 million miles.
Astronomy's use of light as a measurement incorporates the speed of light within these calculations. As such, earth's distance of eight light minutes from the sun means it takes a sunbeam eight minutes to reach the earth's surface.
Type
The field of astronomy is made up of several different approaches. Each approach focuses on a specific method of study. They are Cosmologoy, a theory or myth of the origin of the universe with special emphasis on stars and nebulae; Astrometry, the measurement and movement of angular distances between celestial objects; Planetology, the study of the planets and stars within our solar system; Radio Astronomy, the specific use of radio frequencies to study and gather data on the celestial bodies; and Mathematical Astronomy, the study of the universe using statistics and calculations.
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