THE SOUTHERN HEMISPHERE
BBC Sky at Night Magazine August 2021
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When to use this chart
The chart accurately matches the sky on the
dates and times shown for Sydney, Australia.
The sky is different at other times as the stars
crossing it set four minutes earlier each night.
At first glance the multiple star Xi
(j) Scorpii (RA 16h 04.4m, dec. -11° 22’)
shows only two stars, mag. +5.0 and +7.3,
comfortably separated by 7.9 arcseconds.
A closer look shows the brighter
component consists of two nearly matched
5th magnitude stars at 1 arcsecond apart.
Being binaries (orbital period 46 years),
you are fortunate to catch them at their
maximum separation. Only 4 arcminutes
south of Xi Scorpii is another double of
mag. +7.6 and +8.0 stars, 12 arcseconds
apart – an attractive eyepiece field!
Move eastward by 7° to cross into
Ophiuchus and discover M107 (RA
16h 32.5m, dec. –13° 03’). This 8th magnitude
globular cluster has a dense 2-arcminute
core with a loosely packed halo of stars
reaching to about 6 arcminutes in
diameter. A pair of 8th magnitude stars
(2 arcminutes apart) are 0.4° to the west.
DEEP-SKY OBJECTS
The evenings in August display six of
the seven planets with the exception
being Uranus, which doesn’t rise until
midnight (mid-month). Mars continues its
slow decent in the western twilight glow
and Mercury returns to the evening, making
a close approach to Mars (0.2° apart) as it
passes on the 19th. Mercury is the brighter,
but neither can hold a candle to Venus,
above. The eastern evening sky belongs
to Saturn and Jupiter, with both visible all
night, and Neptune arrives early evening.
THE PLANETS
GALAXY
OPEN CLUSTER
GLOBULAR
CLUSTER
PLANETARY
NEBULA
DIFFUSE
NEBULOSITY
DOUBLE STAR
VARIABLE STAR
COMET TRACK
ASTEROID
TRACK
METEOR
RADIANT
QUASAR
STAR
BRIGHTNESS:
MAG. 0
& BRIGHTER
MAG. +1
MAG. +2
MAG. +3
MAG. +4
PLANET & FAINTER
Chart key
1 Aug at 00:00 AEST (14:00 UT)
15 Aug at 23:00 AEST (13:00 UT)
31 Aug at 22:00 AEST (12:00 UT)
AUGUST HIGHLIGHTS
Jupiter and Saturn are spectacularly
displayed this month with both
planets reaching opposition. Crossing
the meridian close to midnight, these gas
giants dominate the northern sky in a
region devoid of bright stars. Both planets
are at their brightest with Jupiter only
outshone by Venus. Being closest to
Earth, the planets present impressively
larger images than normal. This is an ideal
time to look for features on Jupiter such
as the Great Red Spot and Saturn’s rings.
STARS AND CONSTELLATIONS
In the northern evening sky lies the
Summer Triangle, composed of three
stars. The bottom two are Vega (Alpha ()
Lyrae) in Lyra (left) and Deneb (Alpha ()
Cygni) in Cygnus (right). At the top is Altair
(Alpha () Aquilae) in Aquila, with the names
relating to eagles. However, Altair, along
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also part of the Tarazed asterism, from the
Persian ‘the beam of the scale’. Tarazed
(Gamma (a) Aquilae) is now the name of
the group’s (lower) northern member.
With Glenn Dawes
Enjoy the Summer Triangle in the northern
sky and Jupiter and Saturn at their brightest