Comet tails can stretch out for more than 10 million kilometers. Yet they contain so few particles in total that the material in a com- et tail could easily fit into an average suitcase and leave enough room for a change of clothes.
Comet Tail
A tail is made up of dust and gas from a comet's coma. A tail forms when the solar wind separates dust and gas from the coma, pushing it outward and away from the Sun in either a slightly curved path (for dust) or a straight path (for gas).
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Two types of comet tails may be distinguished. The ion tails are approximately straight, often made up of glowing, linear streamers like those seen in Figure 14.8(a).
Dust Tail - A comet tail that is luminous because it contains dust that reflects sunlight. The dust in a comet tail is expelled from the nucleus of the comet
Dwarf - A main sequence star ...
comet tails (Comet Glossary - JPL) The comet's tail is its most distinctive feature. Generally pointing away from the Sun, these appendages come in a variety of shapes and lengths.
The brilliance of comet tails comes largely from water vapor. On approach to the sun, the ice many comets carry sublimates to vapor, which absorbs and reemits light from the sun.
Comas, Trails and Comet Tails Comets are the "dirty snowballs" of space. They are bodies of ice, rock, gas and dust. The dirty snowball is the nucleus -- the solid center of the comet.
Careful observations of comet tails--for example, of comet Hale-Bopp in 1997-- often show two tails with slightly different directions and slightly different colors, too.
Eugene Parker realised that the heat flowing from the sun in Chapman's model and the comet tail blowing away from the sun in Biermann's hypothesis had to be the result of the same phenomenon, which he termed the "solar wind".
The solar wind can be measured by spacecraft, and it has a large effect on comet tails. It also has a measurable effect on the motion of spacecraft.
The characteristic that a comet tail always points away from the sun is explained by the pressure of the wind pushing it out.
Because of the broom-like appearance of comet tails, the Chinese associated comets with ``sweeping away the old order of things.
Solar wind : aurora, comet tails pushed back
Solar activity, sunspots, magnetic fields, cooler
Sunspot cycle, magnetic field cycle, differential rotation
Prominences, flares, coronal mass ejections ...
Deep Impact waits five minutes as it passes debris in the comet tail, then turns to observe the departing comet for 24 hours.
Data is sent to NASA's 210-ft. Deep Space Network antennas during impact and to 112-ft. antennas for one more week.
A comet tail always points away from the Sun. So the tail (or tails) stream behind the comet as it looms towards the Sun, but when the same comet is retreating back out into the solar system, the tail actually leads the way.
This comet tail also contains a combination of water vapor and dust. The tail usually appears as two tails: a bluish tail of gas, and a whitish tail of dust particles. The tail only exists when a comet is close to the Sun.
And Akasofu recounted that: "The view that interplanetary space is a vacuum into which the Sun intermittently emitted corpuscular streams was changed radically by Ludwig Biermann (1951, 1953) who proposed on the basis of comet tails, ...
Comet tails can stream out up to 100 million km in length! However, the density of material in the tail is not very large.
It has a visible effect on comet tails, blowing the charged-particle component of the comet's tail out away from the Sun as if they were wind socks.
The force of light from the sun pushes dust and gas away from the comet to make the tail. Light from the sun makes the tail glow. The longest comet tail ever measured was recorded in1843. It was 330 million kilometres long.
In this image the orbits are drawn to scale, but the sizes of the planet and comet images (and the length and orientation of the comet tail) are not realistic.
Comet
A body of the solar system, composed of ices and rocks. The frozen material evaporates as the comet approaches the sun and, driven away by the solar wind, forms the comet tail.
(More information can be found here.) ...
Applications of Alfvén's research in space science include: : Van Allen radiation belt theory: Reduction of the Earth's magnetic field during magnetic storms : Magnetosphere (protective plasma covering the earth): Formation of comet tails: Formation ...
The astronomers noted the date, type, constellation in which it was first observed, motion, color, apparent length, and duration in the sky of the comets. They were the first to discover that comet tails always point away from the sun.
Dust tails are usually driven by radiation pressure; ionic (gas) tails are driven by the solar wind. Comet tails do not usually appear until the comet is inside the orbit of Mars. [H76]
Tangential Velocity ...
Type I Tails are straight (ionic tails): Type II Tails are curved (dust tails, little or no charge). Dust tails are usually driven by radiation pressure; ionic (gas) tails are driven by the solar wind. Comet tails do not usually appear ...
Comet comas can extend up to a million miles from the nucleus and comet tails can be millions of miles long.
forces of one of the gas giant planets, causing it to approach , which sometimes propels the small object into a new, very elliptical solar orbit, where it may eventually approach the Sun (and near the Sun, the characteristic comet tail is visible).
to the Sun, the solar wind (charged particles ejected from the Sun) and the Sun's radiation pressure (See Chapter 11.) push the dust and gases of the comets away, this will result in a beautiful long tail. From this, we know why the comet tail is ...
While that may sound small, it is 10 million times the rate lost in the solar wind, which is powerful enough to produce aurorae and comet tails.
 See also: Comet, Sun, Solar, Earth, Solar System
  
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