For thousands of years the night sky has been a place of entertainment and guidance.
It was also the foundation of myths and superstitions. Bright comets were deemed
to be messengers of impending doom such as drought, disease, famine, war, etc. Located
in the outer reaches of our solar system, comets are mountains of rock and ice that
are sometimes nudged toward the inner solar system and round the sun. The outflow
of gas and dust caused by solar heating generates a green fog around the comet and
most times a dust tail and/or ion tail.
For the most part, comets are faint and only seen with a telescope. But such is
not the case with the appearance of Comet 46P/Wirtanen now visible in the southern
sky. Throughout December the comet grows larger and brighter as it races northward.
Closest approach to Earth occurs on December 16 at a safe distance of 11.5 million
kilometres. On the nights of the 15th and 16th, Comet Wirtanen passes between the
Pleiades and Hyades star cluster. The comet could become bright enough to be seen
without optical aid (naked eye) from the dark countryside without the moon present.
As if this bright comet was not enough to enjoy, the annual Geminid meteor shower
peaks on the night of Dec 13/14. The moon sets around 10:30 pm local time allowing
a dark sky for the rest of the night. Best time to see the maximum number of meteors
is after midnight towards dawn when the constellation is highest in the sky. This
shower products 120 meteors per hour as sand size particles from asteroid 3200 Phaethon
(a possible dead comet) completely vapourize as they strike our atmosphere at 35
km/sec. The Geminids also produce occasional fireballs that can light up the ground.
This is a must see event.
Known as “The Backyard Astronomer”, Gary Boyle is an astronomy educator, guest speaker
and monthly columnist for the Royal Astronomical Society of Canada. He has been
interviewed on more than 50 Canadian radio stations and local Ottawa TV. He is now
honoured with renaming of Asteroid (22406) Garyboyle. Follow him on Twitter: @astroeducator
or his website:
The Backyard Astronomer