(or more accurately, 55P/Tempel-Tuttle)
was discovered independently
by William Tempel
in December 1865 and by
in January 1866.
It was calculated that the comet had an
elliptic orbit with a 33-year period.
This information was then used to prove that
Tempel-Tuttle was the same comet that had been
observed by early astronomers in the
year 1366 and again in 1699.
Most people consider
Tempel-Tuttle to be an
inherently faint and typically
unspectacular comet that has only been observed on a
few apparitions over the past 600 years. Its most
recent apparition was in 1998, when it reached
perihelion on February 28. As expected, it showed
little activity, and only a small tail.
However, further inspection showed
that this comet is
more interesting than the first glance would suggest.
Its orbit is oriented in such a way
that the comet makes a relatively
close approach to the Earth every few
apparitions. And more importantly,
the dust trail that the comet leaves behind
is the origin of the annual
Leonid meteor shower.