The Scorpion and the Archer
Look now in the southern sky not far from the horizon. Here we have
two splendid Zodiacal constellations Scorpius, the Scorpion, and
Sagittarius, the Archer. The leading star of Scorpius is Antares, a huge
red supergiant which is a lovely sight even in binoculars. Like Alpha
Herculis it has a faint companion which looks greenish by contrast
with its red primary. Scorpius itself is marked by a line of bright stars
of which the leader is Antares. Unfortunately it is never at its best seen
from British latitudes because it is low down and the Scorpion’s sting is
very difficult to see. This whole area is worth sweeping with binoculars
because the Milky Way is rich here and there are many clusters.
Ajoining Scorpius is Sagittarius, the Archer, which contains the
lovely star clouds that block our views of the centre of the Galaxy. They
are never well seen from Britain, but from southern countries they can
cast shadows.The Perseid Meteor Shower
The best, but by no means the only, summer meteor shower is that of
the Perseids which begins at the end of July and reaches a maximum
around 12/13 August. This is the most reliable shower of the year.
If you wait for a dark sky you are almost certain to see a number of
bright meteors. They are not difficult to photograph but you do need
considerable luck in having the camera pointing in the right place at
the right time.Vega is now very near the zenith, which means that Capella is low
down and grazing the horizon. Deneb in Cygnus is a particularly
powerful star, but very distant, and if it were as close as Sirius it
would cast strong shadows. Cygnus, often called the Northern
Cross, contains many interesting objects and is very rich, because
it is crossed by a particularly bright area of the Milky Way. Of the five
stars making up the cross of Cygnus, the southernmost and faintest,
Albireo, Beta Cygni, is a glorious double star, with a golden yellow
primary and azure blue companion. A small telescope will show the
pair well and there is little doubt it is the loveliest colour double in the
entire sky. Between it and Sadr, the central star of the Cross, there
is a well known variable star, Chi Cygni which can rise to the third
magnitude but becomes very faint at minimum. It is a star of the Mira
type and has an exceptionally long period.Altair
The third member of the Summer Triangle, Altair, is identifiable not
only by its brightness but because it is flanked by prominent stars on
either side of it. Below it is a line of stars, of which the middle member,
Eta Aquilae, is the brightest Cepheid variable in the sky apart from
Delta Cephei itself. Its period is seven days, whereas Delta Cephei has
a period of five days. This shows that of the two, Eta Aquilae is the
more luminous.
As we have noted, Ursa Major is high up, and the region between it
and the Twins is filled mainly by the large dim Lynx. Hercules, roughly
between Vega and Arcturus, is also high up and contains the globular
M13. Note also Alpha Herculis, a red supergiant which varies between
magnitudes three and four. It has a small companion star, which
looks green mainly because of contrast. Close by, we find the large
constellation of Ophiuchus, the Serpent Bearer, with one bright star,
Rasalhague, intertwined with Ophiuchus in Serpens the Serpent. The
two are presumably struggling and the Serpent has come off worse
since it has been pulled in half and there are two separate parts of the
constellation – the head (Caput) and the Tail (Cauda). One star worth
looking at in the tail is Theta Serpentis, which is a fine double whose
components appear to be virtually identical.[1] Albireo, viewed with the naked eye appears as a single star, but with a small
telescope it can be seen to be a beautiful double star. It is the fifth brightest star in
the sky.[2] The Summer Triangle: Deneb, the brightest star in Cygnus in the top left quarter
of the image, makes up the triangle with Vega, in Lyra, at right, and Altair in Aquila
dow towards the horizon.SUMMER (NORTHERN HEMISPHERE)
By the time that the stars of summer are prominent in the sky, Orion and its
retinue have left us. We do have the so-called "Summer Triangle" made up of
three bright stars, Vega in Lyra the Lyre or harp, Deneb in Cygnus the Swan
and Altair in Aquila the Eagle. In fact, the stars of the Summer Triangle are
unrelated and are in different constellations. In a Sky at Night programme
many years ago Patrick Moore referred to these stars as the Summer
Triangle and for some reason the name caught on and is now used widely.1Astronomer Book