Western Australia's Astronomy & Space Science Community


The Sky Tonight

Here you can find an overview for what you might see in the WA skies this month, plus some more information for those with small telescopes and monthly feature info pieces thanks to our resident astronomer - Jacquie Milner.

August 2012


12th – Moon and Jupiter close together, morning sky.

14th – Mars and Saturn together with the bright star Spica in Virgo, evening sky.

14th – Moon and Venus close together, morning sky.

16th – A very thin crescent Moon above Mercury, low in morning sky.

22nd – Moon and Mars together, evening sky.

31st – Blue Moon (second Full Moon in the calendar month)

Moon Phases

Full Moon: 2nd

Last Quarter:  10th

New Moon:  18th

First Quarter: 24th

Full Moon: 31st




Planets to look for

Mars and Saturn meet up during August, high in the western evening sky.  Yellowish Saturn is to the right of white Spica, the brightest star in Virgo.  Orange-coloured Mars will slide between the two over several weeks.  On August 14th they will be in a line: Spica-Mars-Saturn.  But keep an eye on them either side of this date as the configuration changes before and after closest approach.solarsys

In the morning sky Jupiter and Venus start to drift apart after their July meeting. 

Brilliant Venus will stay near the eastern horizon and the Sun but Jupiter will continue on and upwards with the stars of Taurus towards the north. 

Swift Mercury also makes a morning appearance this month but it won’t be an easy apparition this time round. 

Look for it low to the east about half an hour before sunrise during the middle weeks of the month.  A very thin crescent Moon will be above it on the morning of August 16th.

Featured Constellation

Ophiuchus the Serpent Holder

Ophiuchus (Oh-few-kus) lies to the north of Scorpius and is a large constellation that is not always easy to make out.ophiuchus 

None of its stars are particularly bright but it does cover a large area of sky and part of the Milky Way runs through it. 

Ophuichus is said to represent the great healer Aesculepius from Greek mythology.  He reputably knew the secret of how to raise people from the dead, knowledge he gained after watching one snake heal another, and that is why he is always drawn holding a snake up there in the sky. 

Hippocrates the famous Greek healer was said to have been descended from him, too. 

Within the boundaries of this constellation lies Barnard’s Star, a faint red dwarf star that has the largest known proper motion in the sky. 

Proper motion is the speed that a star appears to be travelling through the sky as seen from Earth.  While most stars won’t change their position noticeably within a century or so, Barnard’s star is charging along, covering the apparent diameter of the moon in the sky every 180 years. 

At that speed you could chart its course in your own lifetime.



Objects for the small telescope

Messier 7

If you are lucky enough to be somewhere dark enough to see the Milky Way shining brightly in the sky, take a closer look at the stars under the sting of Scorpius the Scorpion. Do you notice that there seems to be a bright area of stars here?  This is an open cluster of stars known as Messier 7 (M7).

How M7 might appear at a moderate magnification. Image: N.A.Sharp, REU program/NOAO/AURA/NSF

An open cluster of stars is a group of several hundred to several thousand stars that all formed together from the same cloud of dust and gas. 

The dust and gas was blown away from M7 a long time ago and all we see now are the stars that formed.

M7 is an old cluster, estimated to be around 220 million years old.  If you have telescope, you might notice a lot of the stars look a little yellow, or even orange. 

These are signs that the stars here are starting to age and head towards the end of their life cycles. 

M7 looks large in the sky because it is only 800 light years away – that’s pretty close in galactic terms! 

It is large enough that you might enjoy this cluster in a low power view through binoculars, as well as through a telescope at a higher magnification (about x50 is all that is needed).

Please also check out For Casual Observers and Featured Article

For Casual Observers

During July the two brightest planets, Jupiter and Venus, came close together with the Hyades, the star cluster than makes the V-shaped face of Taurus, in the north-eastern sky before dawn.bluemoon 

With so many clear mornings they made an eye-catching sight as they emerged from the twilight together.  They’ve been travelling together for a while now but during August they will gradually drift apart. 

Jupiter will continue towards the northern sky with the Hyades and orange coloured Aldebaran, the eye of the Bull, but Venus will stay low to the east near the Sun.

There are two Full Moons this calendar month, on the 2nd and 31st of the month.  The second moon in a calendar month has come to be known as a blue moon in modern times.

Featured article

Curiosity arrives at Mars

Curiosity, the Mars Science Laboratory, arrives at Mars in early August.  The landing should attract intense interest due to its novel method of delivering the newest robotic probe to the red planet.Rover

Curiosity is much larger than the two preceding rovers, Spirit and Opportunity.  While the rovers are roughly the size of an average person, Curiosity is the size of a small car. 

With more mass to land in Mars’ thin atmosphere, a parachute is of limited use and the airbags used to successfully land the rovers too flimsy to handle the increase in weight so a new method was devised.

Curiosity’s descent will start with a parachute, but then rockets will take over to slow the descent further.  At a certain height from the surface the sky crane should deploy, gently dropping the robotic probe onto Martian soil on long wires before the rockets fire again to take the delivery shell away from the vicinity of the probe.

It all happens at 1.31pm WST (Perth time, or 05.31 UT time) on Monday August 6th if you would like to follow the progress of Curiosity.  The Mars Odyssey orbiter will be watching Curiosity too and will hopefully send back confirmation of a successful landing as soon as it occurs.