 Looking for a comet is called comet sweeping. Astronomers
know that comets often come out of certain areas of space.
They check these sections of the sky every night. Astronomers
are so familiar with the stars in these areas that they
immediately recognize when a new object appears.
Comet sweepers look for rapidly moving, fuzzy
objects. Comets are closer than stars and move very
fast. Their positions seem to change rapidly, often in
just a night or two.
The eighteenth century astronomer Charles Messier
published a catalog of more than one hundred
fuzzy objects observable with a small telescope. As it
turned out, Messier’s fuzzy objects are not comets.
But comet sweepers have to eliminate known
nebulae from consideration. If we’re going to hunt comets, we need
a copy of Messier’s catalog. Then, we use the telescope to locate
each of Meisser’s fuzzies, and memorize its location. Once we’re
familiar with those common fuzzy objects, we’re ready to hunt.
Comets are easier to see if they are close to the Sun. We begin a
sweep by aiming the telescope at an area close to where the Sun
went down. Then we scan a small area at a time, looking for fuzzy
objects. If we find a fuzzy that we know is not in Messier’s catalog,
we’ll check a star atlas and see if it identifi es our fuzzy. If the object
is not in current catalogs, it may be a comet.
Astronomers who think they have discovered a comet should
contact the Central Bureau for Astronomical Telegrams. |
