Our universe is filled with amazing things. Mankind has managed to explore and understand only a fraction of the whole universe. One of things that we human understand for sure is a comet. Having said that, it is also important to say that despite our better understanding of comets, we are still pretty much in darkness when it comes to answering a few questions like, did comets bring water molecules to planet earth or did they bring the primordial life forms? There is much of speculation and debate around these questions and we are pretty sure that this debate is going to continue for some time! So, instead of pondering over those question, let us get back to what we already know and explore 30 interesting comet facts. You may already know them but consider this article as a brush up course!
Interesting Comet Facts: 1-10
1. What is a comet? An icy body releasing dust and/or gas is known as comet. Comets were usually considered as dirty snowballs but recent studies on comets have led scientists to call them as snowy dirtballs.
2. Creation of comets: According to scientists, comets are actually celestial objects that have been created from the leftovers of rocks, dust, ice and gas that were formed some 4.6 billion years ago when the universe was formed. So if that’s true, comets are one of the oldest objects of universe.
3. Comet’s structure: A comet’s main body is known as nucleus. It is also called as the core. NASA says that the core or the nucleus is made of dust with dark organic material coating and ice.
4. Structure of nucleus: NASA further explains that the ice present in the nucleus is made of frozen water, carbon dioxide, ammonia, carbon monoxide and methane.
5. Inside nucleus: The nucleus of a comet in turn has a small core which is usually rocky.
6. Coma – the gas cloud: When a comet gets close to the sun, it gives birth to what is known as coma. Coma is actually the cloud that is formed when the ice on nucleus of the comet turns into gas because of the heat.
7. The dust tail: This coma contains dust particles. These dust particles are pushed away from the coma by the radiations from the sun. These pushed away dust particles then form the dust tail that we see when a comet passes by. The dust tail always and always points away from the sun.
8. The ion tail: Apart from the dust tail, a comet has something called ion tail. As the comet gets closer to the sun, some of the gases in the coma gets converted into ions. These ions are also pushed out by the sun’s radiations, forming the ion tail. The ion tail is not visible to naked eyes. Similar to dust tail, the ion tail always points away from the sun.
9. Is it an asteroid? An advancing comet may sometimes be confused as an asteroid. This may happen because the tail may not be visible at first. To differentiate between a comet and an asteroid, astronomers will always look for the dust tail and the ion tail. Presence of at least one of the tails will mean that the advancing body is a comet and not an asteroid.
10. Size of comets: Comets generally do not have nuclei greater than 16 kilometers or 10 miles wide.
Interesting Comet Facts: 11-20
11. Size of coma: The coma of a comet can extend up to 1.6 million kilometers or 1 million miles.
12. Size of tail: The tail of a comet can extend all the way up to 100 million miles or 160 million kilometers.
13. Why do comets glow? It is the glow of the coma and the dust tail that makes a comet visible to naked eyes. Without the glow, the comets will not be visible to naked eyes. But why do they glow? They glow because of two reasons. First, they reflect sunlight and second, they absorb energy from sun rays. The absorbed energy is then radiated out in form of visible light.
14. Do comets cause meteor shower? Yes they do! A comet almost always leaves behind a debris trail, which lead to meteor shower. For instance, when earth travels through the Swift-Tuttle comet’s orbit every year, she receives the Perseid meteor shower between 9th of August and 13th of August.
15. Short and Long period comets: A short-period comet is one that takes 200 years or less to complete one orbit. Long-period comets on the other hand are those that take more than 200 years to complete one orbital rotation.
16. Single-apparition comets: These are the comets that are by no means bound to the sun. In fact, their orbit is such that they just move out of the solar system.
17. Sun-gazers: Now these are comets that end up smashing right into the sun or they simply get so close to the sun that they break up and eventually evaporate.
18. Where do the comets come from? According to scientists short-period comets that are also known by the name periodic comets originate from Kuiper Belt while the long-period comets originate from the Oort Cloud.
19. Main asteroid belt comets: Scientists say that the main asteroid belt of our solar system (it is a belt of asteroids hanging between the orbits of Mars and Jupiter) is also a source of several comets. Scientists think that the comets originating from this belt are key water sources for inner terrestrial planets.
20. Naming of comets: Comets are usually named named after their discoverers. For instance, Halley’s comet was discovered by Edmond Halley. Sometimes, since space probes also spot comets, those comets have the names of the missions incorporated in them.
Interesting Comet Facts: 21-30
22. Comets and Romans: Even the Romans looked upon comets as bad omen so much that Emperor Nero executed all possible successors of throne just to protect himself from the so-called “curse of the comet”.
23. The omen of Halley’s comet: The Swiss people once blames the famed Halley’s comet for everything bad that happened in Switzerland. They blamed the comet for illness, earthquake, birth of 2-headed animals and red rain.
24. England and Halley’s comet: Even the English people did not leave Halley’s comet. They blamed it for Black Death.
25. Excommunication of Halley’s comet: Sounds ridiculous but that’s true. The tales of comets and disasters were so much intertwined that Pope Calixtus III went to the extent of excommunicating the Halley’s comet.
26. Chinese people and comets: Chinese people were meticulous record keepers of comets. Several comet atlases have been recovered from the ancient Han Dynasty era where records of appearances of comets, their paths and even their disappearances have been recorded very precisely. People from Han Dynasty described comets as “broom stars or long-tailed pheasant stars”. They even associated different forms of comets with different types of disasters.
27. Orbits: Comets usually follow an elliptical orbit around the sun. This is why there is a significant difference between perihelion (the closest distance of a comet from sun) and aphelion (the farthest distance of a comet from sun).
28. Comets can hit earth: Yes, that’s true. Comets can actually hit earth. Scientists say that 28 million years ago, a comet actually crashed into the Sahara Desert. Scientists have actually found in Sahara, a tiny pebble that they call Hypatia. According to scientists, the Hypatia came from the nucleus of a comet.
29. There are many comets: Scientists have actually discovered some 4,000 comets so far and they say that there are actually trillions of them out there in the space.
30. Impact with Jupiter: One comet named Shoemaker-Levy 9 went on to spectacularly collide with Jupiter in 1994. The gravitational tug of the planet ripped the comet into pieces and 21 visible impacts were recorded. A massive fireball rising to the height of 1,800 miles was the result of the largest collision. The collision also left a giant dark spot extending up to 12,000 kilometers across. Scientists estimate that the collision had a force of 6,000 gigatons of TNT!