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Tuesday, August 07, 2012


The Sky This Week - Thursday August 9 to Thursday August 16

The Last Quarter Moon is Friday August 10. Mars, Saturn and the star Spica form a line in the north-western sky on August 14. In the morning skies Jupiter and Venus can be seen not far from each other. On Sunday August 12 Darwin sees the Moon occult Jupiter. On August 14 the crescent Moon is near Venus. See Jupiter and Venus in the daylight. Perseid Meteor shower on 12-12 August.

Morning sky on Sunday August 12 looking north-east as seen from Darwin at 4:00 am local time in the Northern Territory. Jupiter is in the Hyades with the Pleiades cluster is close by.  The Moon is just about to cover Jupiter. The right inset shows the telescopic view of Jupiter and the Moon just before Jupiter is covered. Similar views will be seen elsewhere at the equivalent local time, except viewers south of Darwin will not see Jupiter covered by the Moon (click to embiggen).

The Last Quarter Moon is Friday August 10.

Jupiter climbs higher in the morning sky and is now easy to see. Jupiter moves through the Hyades over the week.

The crescent Moon will occult the planet Jupiter in the early morning hours of August 12 as seen from Darwin. All other cities and locations south of Darwin will see Jupiter very close (less than half a fingerwidth) to the Moon. While this event is easily seen with the unaided eye, binoculars (best mounted on a tripod) or a small telescope will make this a spectacular sight, and you can watch the Moons being occulted as well.

Jupiter will disappear behind the bright limb of the Moon at 4:07 am local time, followed by Ganymede. Io and Europa reappear from behind the dark limb at 4:40 am, followed by Jupiter at 4:41, then Callisto and Ganymede (4:47 and 4:51 respectively). Astronomical twilight begins at 5:50 am in Darwin, so it should be sufficiently dark for good viewing.

With the Pleiades cluster and the constellation of Orion close by, this is a beautiful morning sight. 

Jupiter's Moons are a delight anytime, but on the morning of the 12th, as well as Jupiter being close to the Moon, Jupiter's satellites play hide and seek with a transits of Io and Europa. Well worth a look in even a small telescope.

As the sun rises on the 12, this is also an excellent time to try and see Jupiter in the daylight, using the crescent Moon as your guide.

Bright white Venus climbs higher above the horizon this week. Venus looks like the waxing Moon when seen through even a small telescope. On the 13th the crescent Moon is directly between Jupiter and Venus, and on the 14th the crescent Moon is just above Venus. This is also an excellent opportunity to see Venus in the daylight.

Mercury is lost in the twilight.

Mars is in the constellation of Virgo. It's brightest object in the north-western sky, and its distinctive red colour makes it easy to spot. Mars sets shortly after 10:30 pm local time.

Mars was at opposition on March 4, when it was biggest and brightest as seen from Earth. Sadly, this is a poor opposition and Mars will be fairly small in modest telescopes.

Evening sky looking west as seen from Adelaide at 8:00 pm local time on Tuesday August 14. Mars, Venus and the bright star Spica form a straight line. Similar views will be seen elsewhere at the equivalent local time.  Click to embiggen.

Saturn is above the north-western horizon, not far from the bright star Spica. Saturn is still high enough in the northern sky for telescopic observation in the early evening. Saturn was at opposition, when it is biggest and brightest as seen from Earth, on the 16th of April, but now is still a good time for telescopic views of this ringed world in the early evening.

Mars, Saturn and the bright white star Spica from an attractive triangle in the evening sky at the beginning of the week. Over the week, the triangle becomes smaller as Mars closes in on Saturn and Spica and becomes a straight line on the evening of the 14th.

The Perseid Meteor showere peaks on the 12-13 of August. The Perseids are very low on the horizon in Australia and for all of us south of Brisbane, the radiant (where the meteors appear to originate in the sky) will be below the horizon.

While the ZHR is around 100, Australian observers in the North should expect to see 6-7 meteors per hour under clear conditions. For those north of Brisbane, on August the 12th and 13th, between around 3.30 am and 5.30 am , go out and face North. The meteor shower will be between two to three handspans from the horizon.

A map showing the location of the meteor radiant as seen facing north from Brisbane at 4.00 am is here. (Also useful for Alice Springs and Darwin, Townsville etc. where the radiant is higher). The waning Moon is in the north-western horizon, and this will reduce meteor rates. In Alice Springs there is a 2 hour viewing window, with a maximum of 10 meteors per hour.

With Saturn still reasonably high in the sky, there are lots of interesting things in the sky to view with a telescope. 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.

Cloud cover predictions can be found at SkippySky.


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