Orion’s Belt in December
by Paul Downing
are creeping slowly into winter, and as promised last time we are going to have
a closer look at one of the most interesting constellations in the sky – Orion
the Hunter. If you look in the east
around at the beginning of December you
will see Orion rising. Use the attached
chart to recognise it, and be aware that it will be tilted over on it’s side as it rises.
As it rises higher in the sky during the night it will become more
upright, and this is because objects move across the sky in arcs, not straight
lines. When we look in the direction of
Orion we are looking into one of the spiral arms of our Milky Way galaxy which
is why there are so many bright stars in the area. In fact the brightest star in our skies – Sirius
– is located below and to the left of Orion.
See if you can find it. The top
left star in Orion is called Betelgeuse, often pronounced "beetle juice"
and it is one of the largest stars known.
Shining 60,000 times brighter than our sun it is one of only a dozen or
so stars large enough to show as a disc in our telescopes. If it was located where our sun is, it would
swallow the Earth and extend out to the orbit of Jupiter! Now find the three bright "belt" stars
in Orion and travel downwards until you see some stars and a misty area, which
is known as the Hunter’s sword. This
area, located 1,500 light years from Earth, is of great interest to astronomers
because it is one of the best known examples of what we call nebulae. Nebulae are clouds of gas and dust from which
new stars are formed, and we know that star formation is currently taking place
in this area. Attached is a long
exposure photograph of the nebula, but you don’t need
a telescope to enjoy this object. Find a
pair of binoculars and take a look, you will be amazed
at what you can see.
This article was printed in December 2006
Send your astronomy questions to email@example.com