Dirty Snowballs Of Doom
Throughout history, comets have fascinated human beings, inspiring both awe and fear, and they have often been omens of doom, or curse, or at the very best, thought of as a supernatural force with terrifying abilities. This was true, not only in the ancient times, but also in recent history, in 1910 to be exact, when citizens of Chicago sealed their windows in panic, to protect themselves from inhaling the vapors from the comet’s tail, which they thought were toxic.
Volumes could be written about comets, and there’s still so much we don’t know about them, but for now, we’re gonna give you a quick round-up of the most interesting facts. Comets are a mix of gas, dust and rocks, often called dirty snowballs, or snowy dirtballs by scientists, because they contain ice and water, as well dust particles and rocks. According to research conducted by astronomers, comets were formed about 4,6 billions of years ago, when the Solar System came into existence. They were made up of residual gas and dust that didn’t get pulled into other objects, such as planets, moons or asteroids, by their gravitational force. Most comets have very elongated and unusual orbital paths, reaching far beyond Pluto in some cases, and are often not visible to our eyes unless they are close to the sun.
Comets have three parts: the nucleus, the coma, and the tail. The nucleus is solid, and consist of ice and dust covered in dark organic matter, with ice containing frozen water, but also some other substances, such as frozen ammonia, carbon monoxide, carbon dioxide and methane. As comet’s orbit brings it closer to the Sun, the ice on the surface of the nucleus begins to turn into gas, and forms a cloud know as the coma. The tail is formed when Sun’s radiation forces the dust away from the coma, forming a dust tail, and the charged particles from the Sun convert some of the gases into ions, forming an ionic tail. The tail always point in a direction that is opposite of the Sun.
Astronomers classify comets based on their orbits around the Sun. Short-term comets need less than 200 years to complete a single revolution, while long term comets take more than 200 years to achieve such a feat. Single-apparition comets are comets whose orbit is not bound to the Sun, and their orbits take them outside the Solar System. It is believed that comets originate from Kuiper’s belt, located beyond Neptune. They can differ drastically in size, the smallest one measuring 1 kilometer in diameter, and the largest measuring over 300 kilometers diameter. Comets are usually named after their discoverers, with Halley’s comet probably being the most famous of them all, visible to the naked eye every 76 years. It flew by Earth in 1986, which allowed for more in-depth research of its nucleus, which is normally shrouded by the comet’s coma. Comets disappear when they use of all of their materials, leaving behind only the rocky part. Some scientist suggest that comets brought water, and even organic life, to Earth.