Taurus, Gemini
T
aurusis a large and conspicuous Zodiacal constellation,
representing the bull into which Jupiter once changed
himself for thoroughly discreditable reasons. It has no
well-defined pattern, but it does contain several objects of
special interest.
·(Aldebaran), in line with Orion’s Belt, is an orange-
red star of type K0, 65 light-years away and 140 times as
luminous as the Sun. It looks very similar to Betelgeux,
though it is not nearly so remote or powerful; it makes a
good comparison for Betelgeux, though generally it is
considerably the fainter of the two. The stars of the
Hyades cluster extend from it in a sort of V-formation, but
there is no true association; Aldebaran is not a cluster
member, and merely happens to lie about halfway between
the Hyades and ourselves – which is rather a pity, since
its brilliant orange light tends to drown the fainter stars.
The leading Hyades are Á(3.63), Â(3.54), ‰(3.76) and ı
(3.42). The cluster was not listed by Messier, presumably
because there was not the slightest chance of confusing it
with a comet.
Because the Hyades are so scattered, they are best seen
with binoculars. Ûconsists of two dim stars close to
Aldebaran; ‰makes up a wide pair with the fainter star
64 Tauri, of magnitude 4.8; and ıis a naked-eye double,
made up of a white star of magnitude 3.4 and a K-type
orange companion of magnitude 3.8. The colour contrast
is striking in binoculars. Here, too, we are dealing with a
line-of-sight effect; the white star is the closer to us by 15
light-years, though undoubtedly the two have condensed
out of the same nebula which produced all the rest of the
Hyades.
Messier did include the Pleiades in his catalogue, and
gave them the number 45. Of course, they have been
known since very early times; they are referred to by
Homer and Hesiod, and are mentioned three times in the
Bible. The leader, ËTauri or Alcyone, is of the third mag-
nitude; then follow Electra, Atlas, Merope, Maia, Taygete,Celaeno, Pleione and Asterope. This makes nine, though
the cluster is always nicknamed the Seven Sisters.
However, Pleione is close to Atlas, and is an unstable shell
star which varies in light, while Celaeno (magnitude 5.4)
and Asterope (5.6) are easy to overlook. On the next clear
night, see how many separate stars you can see in the
cluster without optical aid; if you can manage a dozen,
you are doing very well indeed. Binoculars show many
more, and the total membership of the cluster amounts to
several hundreds. The average distance of the stars is just
over 400 light-years.
The Pleiades are at their best when viewed under very
low magnification. The leading stars are hot and bluish-
white, and the cluster – unlike the Hyades – is certainly
very young; there is considerable nebulosity, so that star
formation is presumably still going on. This nebulosity is
very difficult to see through a telescope, but is surprisingly
easy to photograph.
The other nebular object is M1, the Crab, which is
the remnant of the supernova of 1054. It can be glimpsed
with powerful binoculars, close to the third-magnitude ̇;
a telescope shows its form, but photography is needed to
bring out its intricate structure. It is expanding, and inside
is a pulsar which powerful equipment can record as a
faint, flickering object – one of the few pulsars to be
optically identified.
ÏTauri is an Algol variable, easy to follow with the
naked eye; good comparison stars are Á, Ô, Íand Ì. The real
separation of the components is of the order of 14 million
kilometres (nearly 9 million miles), so that they cannot
be seen separately; eclipses of the primary are 40 per cent
total. The distance is 326 light-years; Ïis much more
luminous than Algol, but is also much further away. The
only other Algol stars to exceed magnitude 5 at maximum
are Algol itself, ‰Librae and the far-southern ̇Phoenicis.
Of the other leading stars in Taurus, ̇(Alheka) is a
highly luminous B-type giant, 490 light-years away andATLAS OF THE UNIVERSE
These two large,
important Zodiacal
constellations form part
of Orion’s retinue, and
are thus best seen during
evenings in northern
winter (southern summer).
Taurus contains the two
most famous open clusters
in the sky, the Pleiades
and the Hyades, while the
‘Twins’, Castor and Pollux,
make an unmistakable
pair. The Milky Way flows
through Gemini, and there
are many rich star fields.
Canis Minor is shown here,
but is described with Map 16.AURIGA
GEMINI
CANIS MINOR
TAURUS
CETUS
ORION
ARIES
PERSEUS
AlgolCastorPolluxProcyon BetelgeuxAldebaranHyadesPleiadesRigelM35
M42
M1
·
Û
‚ ÓÙıÈΉ ̇ÂÌ Ë1ÓÁÍ‚Ù ̆
Î
̇
·Â
‰ıÁÏ
90
88
Ì5
ÍÓ10‚·2392
M45
MONOCEROS ERIDANUS
LYNX
CANCER
ÏÁ Ë Û‰ ıÎ^2 Î^1ÍÓÌ Ï
· Á
 ‰
̇ËÎ ‚‚‰Á
·Ì‰Â‚
Ú̇ ÔÂÓÈ̇Â
ËıË^1920
17
27 23ÔMagnitudesVariable starGalaxyPlanetary nebulaGaseous nebulaGlobular clusterOpen cluster–1
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