What is a comet?

Answer 1

A comet is a cellestial body, comprised of mainly ice and dust, there may be heavier metals present eg Iron, nickel, sodium - you may need to undertake some addional reseach.
http://en.wikipedia.org/wiki/Comets

Comets have eccentric orbits - there are two types

Eliptical - which are in permanent orbit of the sun and return at a fixed (short) period - the most famous being Halleys Comet, which visits every 76 years last time 1986 next time 2061.
http://en.wikipedia.org/wiki/Haleys_comet
http://en.wikipedia.org/wiki/List_of_periodic_comets

Hale Bopp visited in 1997 and is due back in 4380 - guess i'll miss it, but saw it in 1997, is a long period comet
http://en.wikipedia.org/wiki/Comet_hale_bop

Parabolic / Hyperbolic - which are drawn into / towards the sun from deep space, make one visit to our solar system before returning to deep space,
http://en.wikipedia.org/wiki/List_of_non-periodic_comets

All comets exhibit a growing tail as they approach perhelion (nearest point to the sun) and the tail always points away from the sun.

Comets are invoved in all sorts of stuff, superstitions, even mass suicides (hale bopp in '97), 1066 and all that (now known to be halleys comet)

Answer 2

A comet is a small body in the solar system that orbits the Sun and (at least occasionally) exhibits a coma (or atmosphere) and/or a tail — both primarily from the effects of solar radiation upon the comet's nucleus, which itself is a minor body composed of rock, dust, and ices. Comets' orbits are constantly changing: their origins are in the outer solar system, and they have a propensity to be highly affected (or perturbed) by relatively close approaches to the major planets. Some are moved into sungrazing orbits that destroy the comets when they near the Sun, while others are thrown out of the solar system forever.

Comets are usually discovered visually or photographically using a wide-field telescope or other optical means of magnification, such as binoculars. However, even without access to optical equipment, it is still possible to discover a sungrazing comet online with a computer and an Internet connection. In recent years, Dave's Virtual Sungrazing Observatory DVSO has enabled many amateur astronomers world-wide to discover a new comet online (often in real time) using the latest SOHO Space Telescope images.

Most comets are believed to originate in a cloud (the Oort cloud) at large distances from the Sun consisting of debris left over from the condensation of the solar nebula; the outer edges of such nebulae are cool enough that water exists in a solid (rather than gaseous) state. Asteroids originate via a different process, but very old comets which have lost all their volatile materials may come to resemble asteroids.

The word comet came to the English language through Latin cometes. From the Greek word komē, meaning "hair of the head," Aristotle first used the derivation komētēs to depict comets as "stars with hair."

Answer 3

Comets are large dirty snowballs made of frozen water and gas, mixed with rock and dust. Like Earth, comets circle around the sun, following a path or orbit. A comet's orbit is egg-shaped, or elliptical.

It is believed that most comets lay frozen in a region of space known as the Oort Cloud, located around 2000 times the distance that Pluto is from the sun. These large chunks of ice and rock just orbit around the sun in this area until one of them gets bumped towards the sun. As it nears the sun it begins to warm up and the ice and rock begin to melt and evaportate, which produces the comets tail. Once this has occured it becomes locked up in that same orbit untill all of its material is used up.

Hope this was useful

Answer 4

Comets orbit the sun just like planets, and return on schedule. Halley's Comet comes close to Earth roughly every 77 years.Earliest reported comet : 600s BC. Halley's Comet was recorded in the Bayeux Tapestry in 1064.

Answer 5

A comet is a small astronomical object similar to an asteroid but composed largely of ice. Comets typically move in highly elliptical orbits, the aphelia of which may be many times more distant than Pluto's orbit. Often described as "dirty snowballs", comets are composed largely of frozen carbon dioxide, methane and water with dust and various mineral aggregates mixed in.

Answer 6

Comets are small, fragile, irregularly shaped bodies composed of a mixture of non-volatile grains and frozen gases. They have highly elliptical orbits that bring them very close to the Sun and swing them deeply into space, often beyond the orbit of Pluto.
Comet structures are diverse and very dynamic, but they all develop a surrounding cloud of diffuse material, called a coma, that usually grows in size and brightness as the comet approaches the Sun. Usually a small, bright nucleus (less than 10 km in diameter) is visible in the middle of the coma. The coma and the nucleus together constitute the head of the comet.



As comets approach the Sun they develop enormous tails of luminous material that extend for millions of kilometers from the head, away from the Sun. When far from the Sun, the nucleus is very cold and its material is frozen solid within the nucleus. In this state comets are sometimes referred to as a "dirty iceberg" or "dirty snowball," since over half of their material is ice. When a comet approaches within a few AU of the Sun, the surface of the nucleus begins to warm, and volatiles evaporate. The evaporated molecules boil off and carry small solid particles with them, forming the comet's coma of gas and dust.

When the nucleus is frozen, it can be seen only by reflected sunlight. However, when a coma develops, dust reflects still more sunlight, and gas in the coma absorbs ultraviolet radiation and begins to fluoresce. At about 5 AU from the Sun, fluorescence usually becomes more intense than reflected light.

As the comet absorbs ultraviolet light, chemical processes release hydrogen, which escapes the comet's gravity, and forms a hydrogen envelope. This envelope cannot be seen from Earth because its light is absorbed by our atmosphere, but it has been detected by spacecraft.

The Sun's radiation pressure and solar wind accelerate materials away from the comet's head at differing velocities according to the size and mass of the materials. Thus, relatively massive dust tails are accelerated slowly and tend to be curved. The ion tail is much less massive, and is accelerated so greatly that it appears as a nearly straight line extending away from the comet opposite the Sun. The following view of Comet West shows two distinct tails. The thin blue plasma tail is made up of gases and the broad white tail is made up of microscopic dust particles.

Answer 7

A celestial body that is composed of a mass of ice and dust and has a long luminous tail produced by vapourisation when its orbit passes close to the sun
"Hale-bott" is a nice example

Answer 8

a celestial body moving about the sun, usually in a highly eccentric orbit, consisting of a central mass surrounded by an envelope of dust and gas that may form a tail that streams away from the sun.

Answer 9

i agree with cheekylegs its like a dixions

Answer 10

one of santas reindeer