to do some serious star recognition, because Orion is so well
placed – and the stars become much more interesting when
you know which is which.
Let us begin with the sky as seen from northern-
hemisphere observers, with Orion high in the south.
Remember that because its stars are so bright, they can be
seen even in strong moonlight; they are far more brilliant
than those of the Plough.
Downward, the three stars of the Belt show the way to
Sirius in Canis Major (the Great Dog), which is much the
brightest of all the stars even though it cannot compete with
Venus, Jupiter, or Mars at its best. It stands out at once; its
magnitude is – 1.5, which means that it is more than 1.5 mag-
nitudes brighter than Rigel (though as so often in astronomy,
appearances are deceptive; Sirius owes its eminence to the
fact that at a mere 8.6 light-years, it is one of the very nearest
of all our stellar neighbours). In the opposite direction –
upward – the Belt shows the way to Aldebaran in Taurus
(the Bull), of magnitude 0.8; Aldebaran, like Betelgeux, is
orange-red, though it is not nearly so large or so powerful.
Continue the line from the Belt through Aldebaran, and you
will come to the lovely star-cluster of the Pleiades or Seven
Sisters, which looks at first sight like a misty glow, though
more careful inspection shows that it is made up of stars.
Next, take a line from Bellatrix through Betelgeux and
curve it slightly; it will lead to Procyon in Canis Minor (the
Little Dog), which is of magnitude 0.4. Procyon is white, and
like Sirius is a relatively near neighbour; its distance from us
is 11.4 light-years.
A line from Rigel through Betelgeux, and extended, will
reach Castor and Pollux, the Heavenly Twins, which are close
together; Pollux (magnitude 1.1) is appreciably brighter than
Castor (1.6), and is orange, while Castor is white.
Almost overhead during winter evenings is the very bril-
liant Capella, in Auriga (the Charioteer); its magnitude is 0.1,
and it is only marginally brighter than Rigel but as seen from
Britain it is far more prominent simply because it is higher
up. It is yellow, like the Sun; close beside it is a small triangle
of stars, known collectively as the Hædi or Kids – two
members of which are very remarkable objects, as we will see
later. Capella is one of only two first-magnitude stars which
can reach the zenith as seen from Britain; Vega is the other.
From the southern hemisphere the patterns of the stars are
the same, but now the Belt points upward to Sirius and
downward to Aldebaran, while Capella is always very low;
from the southernmost part of New Zealand it does not rise
at all. However, the brilliant Canopus, inferior in brilliance
only to Sirius, is not far from the overhead point. Finally,
take note of the Milky Way, which can be seen from either
hemisphere and which runs across the sky from one horizon
to the other. City-dwellers, alas, will not see it, because it is so
overpowered by artificial lights, but when the sky is dark the
Milky Way is truly magnificent.
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