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Comets
are small bodies which orbit the sun in a region beyond Pluto. Several groups
of comets are known, the most famous are those of the Oort Cloud. Here, comets
composed of frozen gases, water ice, and dust left over from the solar system,
lay dormant.
Collisions between comets or interactions with other planets or stars can knock
a comet out of its normal orbit, sending it on a path toward the Sun. When the
comet approaches the inner solar system, the surface ices are heated and evaporate
causing the coma to form. The coma is the "fuzzy" atmosphere that surrounds
the nucleus of all active comets. The gas and dust of the coma are then pushed
away by the solar wind, producing the long, dramatic tails that comets are most
known for.
The distinction between asteroids and comets is somewhat controversial. The main
difference is that comets have considerably more ice and gases in their makeup,
and their orbits are more elliptical than those of asteroids.
Comets and asteroids are primitive bodies, that is, they have been minimally altered
chemically or physically since the formation of the solar system. Meteorites and
other bits of cosmic debris that fall to the Earth are fragments from comets and
asteroids that we can study directly in our laboratories, thus aiding scientists
in their study of the birth of planets.
When
was Hale-Bopp Discovered, and How was it Named? Hale-Bopp
was discovered on July 23, 1995. The discovery was made independently by two amateur
astronomers, Alan Hale, and Thomas Bopp. Both astronomers first detected the new
comet in a region outside Jupiter's orbit. Comets are traditionally named for
their discoverers, thus the comet has been designated Hale-Bopp.
The numerical designation C/1995 01 contains pertinent information about the object.
The "C" indicates that Hale-Bopp is a long period comet (one with a
solar orbiting period of more than 200 years), and 1995 is the year of discovery.
The "01" means that this was the first comet found in the second half
of the month of July. Each half month through the year is given a letter designation,
thus the letter "A" covers Jan. 1-15, "B" represents Jan.
16-31, etc.
What
is Special About Comet Hale-Bopp?
Hale-Bopp is unusual because of its
brightness and its location at the time of its discovery. No comet has ever been
discovered so far out in the solar system by amateur astronomers. Hale-Bopp appeared
1,000 times brighter at its discovery beyond Jupiter's orbit than Comet Halley
(Hale-Bopp's most famous cousin) did when it was at that same distance from the
Earth. Most astronomers say we should not be surprised if Hale-Bopp becomes the
brightest comet on record.
How
Can I See Hale-Bopp?
Hale-Bopp is already visible to the naked eye and
will become spectacular by the end of March. Hale-Bopp's closest approach to Earth
will occur on March 22, 1997 at which point it will be 120 million miles away.
During the period between March 28 and April 12, it is expected to be near peak
brightness (0 to 0.5 magnitude). The comet will be visible in the northwest shortly
after sunset. By this time, the comet will be displaying a noticeable tail. A
comet's tail can stretch to millions of miles in length.
For inexperienced comet watchers, Hale-Bopp will appear to the naked eye as a
bright star with a tail in the northwest. When viewing the comet, a good pair
of binoculars is often preferable to a telescope. Binoculars with a strength of
8 x 50 or 10 x 50 will work quite well. Comets can often be disappointing when
viewed through a backyard telescope. They are inherently "fuzzy" objects
and telescopes only increase this effect. Another advantage of binoculars is their
wider field of view, allowing you to bring the entire comet into focus. They also
offer portability and ease of use for first-time observers.
Check
the following sources for the latest information on Hale-Bopp: Check
the following sources for more information on asteroids: Back
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