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Wednesday, October 23, 2013


The Sky This Week - Thursday October 24 to Thursday October 31

The Last Quarter Moon is Sunday October 27. Mars and Jupiter are prominent in the early morning. The Moon visits Jupiter on the 26th and the crescent Moon is near Mars on the 30th. Venus is easily visible in the western evening sky above  the bright star Antares. Mercury and Saturn are low in the evening sky. Comet C/2012 S1 ISON visible in telescopes not far from Mars.

The Last Quarter Moon is Sunday October 27. Moon is at apogee on the 25th.

Evening sky looking west as seen from Adelaide at 20:15 pm ACDST  on Saturday October 26. Venus is quite high in the evening sky above Antares. Saturn and Mercury are low on the horizon. The insets shows the telescopic view of Venus and Mercury at this time. Similar views will be seen elsewhere at the equivalent local times.  Click to embiggen.

Venus  climbs higher in the evening twilight. It can easily be seen shortly after sunset (indeed, with a little effort you can see it before sunset). The brightest (spectacularly so) object above the western horizon it is visible up to three hours or more after sunset (depending on how flat your western horizon is).

Venus starts the week close  to the bright star Antares and continues its journey up the body of the Scorpion into the constellation Ophiuchus. It is a distinct half moon shape in even small telescopes

Mercury  is still easily visible in the evening twilight. Mercury is lower in the evening sky this week heading towards the horizon, but remains reasonably visible for the rest of the week.Mercury is a crescent in telescopes.

Saturn is still visible above the western horizon in the early evening twilight in the constellation of Virgo. It is now too low in the twilight for telescopic views, and will be effectively lost to sight by the end of the week.

Morning sky on Saturday October 26. looking north-east as seen from Adelaide at 5:30 am ACST in South Australia. Comet C/2012 S1 ISON is to the right of Mars, and visible in amateur telescopes. The inset shows the view of Jupiter through a telescope at this time. Similar views will be seen elsewhere at the equivalent local time (click to embiggen).

Jupiter is in the constellation Gemini. Mars is is in the constellation of Leo.

Mars rises still higher in the morning twilight, and is visible well before twilight.  Mars starts the week not far from the bright star Regulus and continues to draw away during the week. Mars is also not far from comet C/2012 S1 ISON.

The crescent Moon is near Mars on the 30th.

Jupiter is now well above the north-eastern horizon near the bright stars Castor and Pollux, the twins of Gemini. It is quite easy to see in the morning sky well into the twilight.  Jupiter's Moons are now readily visible in binoculars.

The Moon visits Jupiter on the 26th.

Comet C/2012 S1 ISON is continuing to brighten. Currently it is visible in modest amateur instruments such as  8" reflecting telescopes and has been imaged with DSLR cameras at high ISO values.

The image to the left shows a high power view of the region around Mars with ISON (expanded from the unaided eye view above).

While the comet is somewhere around magnitude 9-10, the bright Moonlight making magnitude estimation hard. It is never very high at Astronomical twilight (5 and 7 degrees above the horizon in most of Australia). While the comet should be visible in smaller telescopes such as 4" reflectors and strong binoculars, the proximity of the bright Moon makes spotting the comet difficult. You can get a PDF map suitable for printing here.

The comet is  to the right of Mars, theoretically making finding it relatively easy, but the Moon interference (see above) makes it hard to distinguish.

There are lots of interesting things in the sky to view with a telescope. Especially with Venus so prominent in the sky.  If you don't have a telescope, now is a good time to visit one of your local astronomical societies open nights or the local planetariums

Printable PDF maps of the Eastern sky at 10 pm AEST, Western sky at 10 pm AEST. For further details and more information on what's up in the sky, see Southern Skywatch.


The unfortunate circumstance of the Blue Mountains fires had a fortunate side effect last night. The sunset at Lake Macquarie was so heavily filtered by the smoke that I got out the binoculars just before sunset and could directly see the sunspots on the sun ! It looked just like the picture on Space Weather.

Don't try this unless you're certain almost all of the sun's energy has been filtered out !
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