Comets are composed mostly of various kinds of ice (which is to say, frozen liquids and gases, not just water ice) and when they approach the sun parts of them will boil away, which produces the distinctive comet's tail. Farther from the sun they have no tail, and remain frozen.
comets are more clearly visible when they approach the sun because they release vast clouds of gas and dust as they approach the sun, causing them to heat up and form a bright and long tails, often millions of kilometers long...
When comets gets closer to the heat of the Sun, they start to evaporate. gas and dust form long tails that point in the direction of the strongest gravity field. we can see the suns light reflect from the matter that makes up the tail. These tails can be millions of miles long and don't travel in the wake of the comet.
We can see comets because of their long glowing tail and bright fuzzy head. But the glowing tail and fuzzy head are actually just a little bit of scattered dust, carried away from the coal-black head of the comet by the melting of the frozen gasses that it is made of.
Far from the Sun, the gas stays frozen, and the comet is invisible. It is only as it begins to approach the Sun (and "approach" only relatively, since many comets become visible beyond the orbit of Jupiter!) that the frozen gas begins to sublimate away and carry the dust out into space. This is when it begins to reflect the Sun's light, becoming visible to astronomers and (hopefully) to us here on Earth.
This also means that every periodic comet will eventually burn out; the supply of gassy ices that stream away from the head of the comet is finite, and is never replenished. When the supply of ice is all melted, the dust and rocks from the comet's head will become just another bunch of meteoroids invisibly falling through space.
The orbit of most comets is significantly elliptical.
It seems that as the comet nears the sun, the attraction between the two bodies greatly increases, and therefore, acceleration occurs such that the speed of the comet's approach to the sun greatly increases. Nevertheless, being quite small, it quickly rounds the sun while at close distance and is flung like the recoiling of an elastic band back out into space (possibly assisted by some other external attraction in space).
It would seem that, nevertheless, the attraction of gravity between the sun and comet causes the inertial departure to eventually slow down: 'escape inertia' is overcome, and the body commences on its acceleratory path back towards the sun again.
Bad premise; MOST comets are invisibly dim, often just barely reaching a threshold of visibility. It's the rare and unusual comet that is so spectacularly bright. There were over a dozen comets seen in 2010; did you see any of them? I believe that the brightest barely reached 6th magnitude.
Comets glow by reflected sunlight. The nucleus of the comet isn't very spectacular, but the heat from the Sun will cause frozen gasses to sublimate (become vapor again) and carry dust away from the nucleus. This spreads out a lot in the "solar wind", and the Sun's light reflects from that. To become a major comet, it must be fairly big or fairly close, or both.
Comets don't face anything. The comet's tail, however, will go away from the Sun, because that's the direction the solar wind blows: away from the Sun.
Comets don't face anything. The comet's tail, however, will go away from the Sun, because that's the direction the solar wind blows: away from the Sun.
Comets don't face anything. The comet's tail, however, will go away from the Sun, because that's the direction the solar wind blows: away from the Sun.
Comets don't face anything. The comet's tail, however, will go away from the Sun, because that's the direction the solar wind blows: away from the Sun.
The closer it gets to the sun, the stronger the sun's gravitational pull on the comet.
Comets become more visible when they are closer to the sun because the sun's heat is actually melting/ripping apart the ice and dust off the comet giving it that familiar bluish color.
The closer to the sun, the larger the tail. The further a comet gets from the sun, the shorter the tail is.
None. Comets have a tail, but that's not "usually", only when they are close to the Sun (which is when we see them, of course). Most of the time, when they are far away from the Sun, they have no tail. The tail is caused by the solar wind.
The nucleus is the bulk of the comet, this is present all the time until it eventually breaks up after many orbits. close to the sun, it gives of two tails as the sun heats the comets surface. Far from the sun it would just look like a rock that also contains a high proportion of ice.
Comets have been compared to "dirty snowballs", made of rocks and dust held together with frozen gasses. When a comet starts to come near the Sun, the sunlight begins to heat it up, vaporizing some of the frozen gasses. The dust in the ice is carried away with the vapor, and the light pressure from the Sun pushes the very light dust and vapor away from the comet's nucleus. The light illuminates the dusty vapor, and we see the comet's tail begin to grow as the comet comes closer to the Sun.The length of the tail is dependent on the nature of the frozen gasses, and on how much dust the tail carries away, and on how close the comet comes to the Sun. Some comets don't come especially close to the Sun, while some come VERY close. And some comets fall into the Sun completely. (The size of any comet is so tiny compared to the size of the Sun that a comet-Sun collision has no effect on the Sun at all. It would have less impact than the force of a mosquito hitting the windshield of a train.)
"Down" is the direction of the greatest mass, which, in the Solar System, is the Sun. The reason ALL comets haven't fallen into the Sun is that there also have angular momentum, which results in them falling AROUND the Sun.
The comets with long periods of revolution around the Sun.
No. Mercury has nothing to do with comets. Comets are objects that orbit the sun independent of the planets.
Earth
when it gets close to the atmosphere
As close as they want - including crashing into it. Gravity and inertia control their orbits.
They get two close to the sun and some breaks off.
comets orbit the sun
Comets have their own orbits in our solar system around the sun. They don't come close to the earth.
Comets orbit the Sun.
Comets are balls of ice and dust in orbit around the Sun. The orbits of comets are different from those of planets - they are elliptical. A comet's orbit takes it very close to the Sun and then far away again.
The sun's gravity holds comets in their orbits.The sun's radiation heats comets causing vaporization of their ices.The sun's solar wind blows vaporized ice and dust particles away from the comets forming the tail.The sun's visible light reflects from the comet and its tail, making them visible.The sun's magnetic field deflects ions in the tail, causing separation into two tails - the dust tail and the ion tail.If a comet comes too close to the sun, the comet will hit the sun and be destroyed.
No. Comets orbit the sun.
Those astronomical objects are called comets.