Comets

When Halley's Comet passed in the early XXth Century, there was just enough science to analyze the chemical content of the tail, but not enough scientific familiarity in the general population to make sound evaluations about scientific findings.

It happened that spectrography showed the comet's tail, through which the Earth would pass, contained hydrogen cyanide, which everybody knew was a poison. What they failed to appreciate was the extremely low concentration of it.

Of course, there's a long history of comets scaring people, as folks are used to a very steady and unchanging sky and anything that goes "wrong," such as a comet or an eclipse, simply MUST be cause for concern.

Comets are celestial bodies that orbit the sun. They are composed of ice and dust.

A meteor is an object (perhaps a comet or a piece of one) that has struck the atmosphere and become superheated so that it leaves a fiery trail. When it has struck the ground, it is a meteorite.

The distance of a comet from the sun varies greatly. Much more so than for any of the planets, in fact. Comets orbit the sun in long, long eliptical orbits. The orbits of comets can take them from the inner planets outward to space far beyond the orbits of the outer most planets.

The average size of a comet can vary greatly, ranging from a few hundred meters to tens of kilometers in diameter. The nucleus of a comet is typically smaller than a few kilometers, while the coma and tail can extend over much larger distances due to the interaction with the solar wind and radiation pressure.

i believe in superstition because it helps us to be learn more but i think with scientific basis......

The tail of a comet is made up of a combination of frozen rock, and ice particles coming off the comet and is lit up by the sun. If you were to be in this tail, you would face: subzero temperatures and constant pummeling by SOLID ice and rock.

This is because as they approach the Sun, gravity acts more on them and they speed up. They then have enough momentum to "sling" themselves back out of the solar system. Gravity will slow them down again as they travel away from the Sun and so on it goes.

The famous writer Mark Twain- Samuel Langhorne Clemens was born in the year of Halley"s appearance and died, also in the year of it"s appearance in l9l0. No major world crisis was ( Keyed) to the Comet, the Titanic disaster came in 4.l4-l5.l2 two years down the pike.

All comets (there are over 3,500 known) have different time-scales for their appearances.

These depend on the length of their orbits - some comets have extremely large orbits which take them from being 'close' to the earth to almost going out of our solar system.

They appear because they come close enough to the Earth to be seen, and then they may take anything from a few years to hundreds of thousands of years beore they come back.

The best-known comet is Halley's Comet which has a period of between 75 and 76 years between appearances.

Comets originate in the 'Oort Cloud' - a cloud of ice and debris surrounding the solar system far out beyond the orbits of the planets. If one of these pieces of debris manages to succumb to the sun's gravitaional pull rather than hat of the surrounding bits of debris, it will begin an orbital path round the sun, in an elongated elipse (like a cigar-shape). This is what we call a comet. As the comet is in orbit round the sun, it will reappear near earth at intervals.Some comets have a relatively short reappearance time - the most famous being Halley's Comet at 76 years. Some comets take 3000 years to reappear or even more. When it approaches the sun at distance it is simply a block of ice and rock. However, when it gets near the sun, the solar wind ( a stream of radiation from the sun) and radiation melt the surface of the comet so that a tail emerges. (actually two tails form - but the reasons need not be explored here). The characteristic tail is what we see when looking at a comet. The tail always faces away from the sun (not behind the comet in the direction of travel, which is commonly, but wrongly believed) because of the solar wind pushing away debris in a direction opposite to the sun. After its orbit the comet will return to the Oort cloud as its tail disappears (as the solar wind has less effect) to begin its journey round the sun again. After several journeys, the comet will lose more and more material (that forms the tail) because of the Solar wind. There will come a time when the comet eventually dies out like an icecube melting on a hotplate.

Yes, meteors (meteoroids entering Earth's atmosphere) do not have tails. However, when a meteoroid vaporizes upon entry, it can create a glowing trail of light behind it known as a meteor train, which can appear as a temporary tail.

It rather depends on the path of the comet. Some comets (such as Encke's comet) return in as little as 20 years - others might not return to our solar system for centuries (Comet McNaught has an orbital period of over 92,000 years !) It's possible to see at least one comet per year if the weather conditions ar favourable.

Some meteor showers are caused by Earth passing through the remnants of an old comet or parts of the trail of debris left by comets. The Leonid meteor shower is caused by Earth passing through the trail of comet Temple-Tuttle.

The comet's tail forms as it approaches the Sun because the Sun warms the comet up and it starts to sublimate. That cloud of gas that forms the tail points away from the Sun because of the force of the Solar Winds that are generated by the Sun's emmisions into space.

They come from the outer reaches of space.

Yes, it was last seen in 1986. The next time it will be visible from planet Earth is the 28th July in the year 2061.

I made a wish, I was 16 years old when my father drove us up to the top of a mountain in S. Phoenix to admire the comet. I for some reason decided to make a wish, that my boy crush at the time would one day fall in love with me. I was madly in love with him and my mother said its just a crush and its impossible for me to be in love at such a young age. She was wrong over the next few years my love for him deepened as our friendship had grown. I finally had the courage to tell him how I felt when I was in college but I told him too late he was engaged to be married. That marriage failed and over the years we both were in other relationships but remained friends and stayed in contact via emails. It was not until recently he told me that he realized how much he loved me and recognized me as his soul mate. My wish had come true but it took nearly 30 years.

when a comet gets close to the sun the frozen liquid in the Nucleus starts to vaporize and turn into gas and the rock particles are released and turn to dust so somtimes you can see 2 tails one that's blue which is the gases and one that's yellow-white which is the dust.

[hope this information helps out]

by the way im only 12 and i knew this stuff off by heart

Rocky asteroids. Icy comets often live in and come from the Kuiper Belt.

It takes roughly 75 years for Halley's comet to come by the earth. All comets orbit the sun, but they do not all originate from the same place, which accounts for their paths and how long their individual orbit takes.

The "coma".

A comet has a long tail (hence the name comet meaning long-haired star) while a meteor is only a beam of light.

This is a chronological list of known human sightings of the Halley comet.

* 25 May, 240 BC * 12 November, 164 BC * 6 August, 87 BC * 10 October, 12 BC * 25 January, 66 AD * 22 March, 141 * 17 May, 218 * 20 April, 295 * 16 February, 374 * 28 June, 451 * 27 September, 530 * 15 March, 607 * 2 October, 684 * 20 May, 760 * 28 February, 837 * 18 July, 912 * 5 September, 989 * 20 March, 1066 * 18 April, 1145 * 28 September, 1222 * 25 October, 1301 * 10 November, 1378 * 9 June, 1456 * 27 October, 1607 * 15 September, 1682 * 13 March, 1759 * 16 November, 1835 * 20 April, 1910 * 9 February, 1986