52 | New Scientist | 30 October 2021
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newscientist.com/makerWhat you need
Clear, dark skies
Binoculars (optional)IN NOVEMBER – at least in the part
of the northern hemisphere I call
home – the nights begin to get
darker, the leaves turn all sorts
of shades of orange and my dogs’
paws seem to get muddier on
every walk. But the one thing that
really signals to me that winter is
on its way is when Orion appears
in the early evening sky.
Orion the hunter is an iconic
part of the night sky. Stargazers
anywhere in the world can find
the constellation using the three
stars in the asterism Orion’s belt
(pictured). But Orion can also be
used to navigate to other parts
of the sky. This week, in honour
of my two dogs, Peanut and Jack,
we will be using Orion to find two
constellations named after dogs,
Canis Major and Canis Minor. I like
to imagine them running along
faithfully behind Orion.
From the northern hemisphere,
Orion appears with the red giant
Betelgeuse above and left of the
belt, and the blue star Rigel below
to the right. The dog constellations
are to the left of Orion from this
orientation. In the southern
hemisphere, Orion is the other
way up and the dogs are to its right.
Let’s start with Canis Major.
This contains the brightest star
in the night sky, Sirius. To find
Sirius – which is actually a binary
star system, not a single star –
draw a line along Orion’s belt. In
the northern hemisphere, this line
goes from right to left, and it is the
opposite way in the south. Keep
going until you come across a star
that appears to twinkle brightly,
and you have found Sirius.Use Orion as a starting point to find its faithful companions,
Canis Major and Canis Minor, says Abigail BeallStargazing at home
Sniff out the dogs
All stars seem to twinkle
because of the turbulence in
Earth’s atmosphere affecting the
path of light reaching our eyes.
Sirius is the clearest example of
this effect. This is partly because
it is so bright, but also because it
appears low on the horizon in the
northern hemisphere, so there
is more of the atmosphere for
its light to travel through.
Twinkly Sirius makes up the
neck of the dog in Canis Major.
To find the rest, look below Sirius
in the northern hemisphere. You
will find a triangle of three stars,
which make up the dog’s tail and
the top of its back legs.
While Canis Major is quite
clearly shaped like a dog, the
constellation of Canis Minor
requires a lot more imagination.
The pattern is made up of twobright stars. To find Canis Minor,
you need to use Betelgeuse, Rigel
and Sirius. Imagine these stars
make up three of the four corners
of a parallelogram. Where you
imagine the fourth would be,
look around that part of the sky
for a bright star. That’s Procyon,
and once you have it, you have
found Canis Minor.
Like Sirius, Procyon is a
binary star, comprised of a main
sequence star orbited by a white
dwarf. Procyon is the eighth
brightest star in the night sky
because it is quite close to us at
only 11.5 light years away, although
it isn’t as bright as Sirius, which
Stargazing at home is “only” 8.6 light years away. ❚
appears every four weeksNext week
Science of gardeningAbigail Beall is a feature editor
at New Scientist and author of
The Art of Urban Astronomy
@abbybeallFeedback
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