The Leonids is a
meteor shower
that occurs every year in mid-
November
(typically between the 13th and 20th).
The
meteors are called Leonids because
they seem to
radiate out of
the
constellation Leo (making Leo
their "
radiant").
Most meteors are produced by comets,
and the Leonids are no exception.
Every year, the Earth passes through
the ice- and dust-trail of the comet Tempel-Tuttle
(which can be seen every 33 years),
resulting in a sometimes spectacular
meteor shower.
In some cases, when the Earth travels through fresh
cometary matter rates increase drastically,
and if we're lucky we will see
a meteor storm with up to several
thousand meteors per hour, even
several per second in short bursts.
The Leonids are fast meteors, causing them
to leave bright trails, which can last
from a few seconds to several minutes.
The particles, usually between 1 mm
and 1 cm in diameter,
enter our atmosphere in speeds
exceeding 158,000 mph.
The best way to observe the show is to dress
warm, and lie down with your feet pointing
east, towards Leo. Looking directly at
the radiant isn't necessarily the best
way to observe. Instead, look around
and above it.