Astronomy

John Michael Handrop
Summer 2009

Astronomy:

         Astronomy is the science of celestial objects, such as stars, planets, comets, and galaxies, and phenomena that originate outside the Earth's atmosphere such as auroras and cosmic background radiation. It is related to the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the formation and development of the universe. The word astronomy literally means law of the stars and is derived from a Greek, which I forgot.
         Astronomy is one of the oldest sciences. Astronomers of early civilizations observed the night sky, and astronomical artifacts have been found from much earlier periods.
         Since the 20th century, the field of professional astronomy split into observational astronomy and theoretical astrophysics. Observational astronomy is concerned with acquiring data, which involves building and maintaining instruments, as well as processing the results. Theoretical astrophysics is focused upon finding the observational developments of computer or theoretic models. The two fields complement each other, with theoretical astrophysics seeking to explain the observational results. Astronomical observations can be used to test fundamental theories in physics, such as general relativity.

         Kepler's three laws are:
                   1) The orbit of every planet is an ellipse with the sun at one of the foci. An ellipse is characterized by its two focal points; see illustration.
                   2) A line joining a planet and the sun sweeps out equal areas during equal intervals of time as the planet travels along its orbit. This means that the planet travels faster while close to the sun.
                   3) The squares of the orbital periods of planets are directly proportional to the cubes of the major axis of the orbits. This means not only that larger orbits have longer periods, but also that the speed of a planet in a larger orbit is lower than in a smaller orbit.

         Newton’s theories Philosophiae Naturalis Principia Mathematica, published in 1687, described universal gravitation and the three laws of motion, laying the groundwork for classical mechanics. By demonstrating consistency between Kepler's laws of planetary motion and this system, he was the first to show that the motion of objects on Earth and of celestial bodies are governed by the same set of natural laws.

Comets And Asteroids:

         A comet is a small body in the solar system that orbits the Sun, has an atmosphere, and tail. Both from the effects of solar radiation upon the comet's nucleus, which itself is a minor body composed of rock, dust, and ice. Comets orbit constantly change their origins, but are in the outer solar system, and they are highly affected by close approaches to the major planets. Some are moved into the sun grazing the orbit that destroys the comets when they get near the Sun, while others are thrown out of the solar system forever.

         Most comets are believed to originate in a cloud, at large distances from the Sun consisting of debris left over from the condensation of the solar nebula. Asteroids originate a different process, but very old comets which have lost all their volatile materials may come to resemble asteroids.

         Asteroids, also called minor planets or planetoids, are a class of astronomical objects. The term asteroid is generally used to indicate a diverse group of small celestial bodies that drift in the solar system in orbit around the Sun. Asteroid is the word used most in the English literature for minor planets, which has been the term preferred by the International Astronomical Union (IAU). In late August 2006, the IAU introduced the term small solar system bodies, which includes most objects classified as minor planets, as well as comets. At the same time they introduced the term dwarf planet for the largest minor planets.

Conclusion:

         Astronomy is important to use, because it strives us to constantly upgrade our technology, as well as explain the knowledge of how we came to be, or even if there are other planets we can live on, or extraterritorial life. Astronomy is also important to the survival of this race, because if something bad happens to this solar system hopefully we will have humans on another solar system or even another galaxy.