There are stray objects in our galaxy that astronomers have identified, named, categorized, and researched; or they have hypothesized these objects’ impacts on earth or on other objects in galaxy. Since these roaming around objects, with known chemical components, are mostly recognized, I would like to call them identified flying objects. Three of the most well known of these objects are: comets, asteroids, and meteoroids.
Asteroid Asteroids are referred to as minor planets. They are smaller than planets but larger than meteoroids. 10,000 of meteor debris fall into earth every year. The largest ones are comets and asteroids.
Learning about the origin of earth started 400 years ago by the help of Galileo, Kepler, and Newton. Tollmanns, the husband and wife astronomers, proposed that around 7,640 BC some asteroids or comets hit the earth, followed by some more strikes in 3,150 BC. According to Tollmanns, Noah's flood actually happened as a result of the first strike. The universe was supposed to be very different in the old time. Through passing of time, changes have occurred as a result of such impacts.
Old civilizations of 3,000 to 6,000 years ago could have suffered tremendous impacts by the objects falling from sky. Disappearance of such civilizations as Minoan around 1,450BC and Mycenaean around 1,200BC are blamed on such impacts. It is also proposed that biodiversity and extinction events may be as a result of cyclic processes. A hypothesis by Raup and Sepkoski suggests an extinction event by a cyclic process of 26 million to 30 million year cycle.
Following is a picture of Primordial Quasar, with this explanation (from Illinois Department of Astronomy): "What did the first quasars look like? The nearest quasars are now known to be supermassive black holes in the centers of galaxies. Gas and dust that falls toward a quasar glows brightly, sometimes outglowing the entire home galaxy. The quasars that formed in the first billion years of the universe are more mysterious, though, with even the nature of the surrounding gas still unknown. Above [below], an artist's impression shows a primordial quasar as it might have been, surrounded by sheets of gas, dust, stars, and early star clusters. Exacting observations of three distant quasars now indicate emission of very specific colors of the element iron. These Hubble Space Telescope observations, which bolster recent results from the WMAP mission, indicate that a whole complete cycle of stars was born, created this iron, and died within the first few hundred million years of the universe." Each day, a new picture is printed on the site where this picture is borrowed from, for interested visitors. The site address is: http://www.astro.illinois.edu/
Comets The origin of the word comet is from the Greek word “Kome” which means “hair”, or the Latin word “Cometes”. It is a small icy object with dust and rocky particles in the solar system which has three hair-like tails. Most famous comets are: Halley, Shoemaker, Hale-Bopp, Encke, Kohoutek. The comet object exploded in 6/30/1908 flattened trees and killed reindeers for 20KM. The first collision of two solar system bodies was observed from July 16 through July 22, 1994, when comet Shoemaker-Levy 9 collided with Jupiter. Comet Shoemaker-Levy 9 consisted of at least 21 discernable fragments with diameters estimated at up to 2 kilometers.
Meteoroid The word meteoroid is taken from the Greek “meteoros” meaning “high in the air. It is a sand or rock particle in the solar system. When it enters the earth’s atmosphere it is called meteor, and meteor shower is when a group of them are seen in the sky. The part that hits the ground is called meteorite. Since the planets were formed 4.5B year ago, the debris which have been left over called "meteoroid" have been scattered around. The smaller ones "meteor" burn up in the atmosphere with a fiery trail which we call shooting star.
Asteroid Asteroids are referred to as minor planets. They are smaller than planets but larger than meteoroids. 10,000 of meteor debris fall into earth every year. The largest ones are comets and asteroids.
Learning about the origin of earth started 400 years ago by the help of Galileo, Kepler, and Newton. Tollmanns, the husband and wife astronomers, proposed that around 7,640 BC some asteroids or comets hit the earth, followed by some more strikes in 3,150 BC. According to Tollmanns, Noah's flood actually happened as a result of the first strike. The universe was supposed to be very different in the old time. Through passing of time, changes have occurred as a result of such impacts.
A big bang occurred about 13.7 billion years ago. Since then, universe has been expanding, noticing that further away galaxies are moving away from us faster than the closer ones. After many exchange of chemicals as a result of cooling and turning, Milky Way was formed. Our planet earth was born at the edge of the Milky Way about 4.5 billion years ago. After an impact with another planet it became tilted, as it is now, and without it life the way we know it could not form. The debris from this impact created moon which was caught in earth's orbit. The moon stabilized revolution of earth which created the climate necessary for the living organisms. All the craters in the moon were as a result of an impact with an asteroid, a comet or a meteoroid. Comets continued impacting earth and they brought with them some materials (such as carbon) which were essential for foundation of life.
Following is a picture of Primordial Quasar, with this explanation (from Illinois Department of Astronomy): "What did the first quasars look like? The nearest quasars are now known to be supermassive black holes in the centers of galaxies. Gas and dust that falls toward a quasar glows brightly, sometimes outglowing the entire home galaxy. The quasars that formed in the first billion years of the universe are more mysterious, though, with even the nature of the surrounding gas still unknown. Above [below], an artist's impression shows a primordial quasar as it might have been, surrounded by sheets of gas, dust, stars, and early star clusters. Exacting observations of three distant quasars now indicate emission of very specific colors of the element iron. These Hubble Space Telescope observations, which bolster recent results from the WMAP mission, indicate that a whole complete cycle of stars was born, created this iron, and died within the first few hundred million years of the universe." Each day, a new picture is printed on the site where this picture is borrowed from, for interested visitors. The site address is: http://www.astro.illinois.edu/
