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Tuesday, April 21, 2015


The Sky This Week - Thursday April 23 to Thursday April 30

This is Global Astronomy Month. The First Quarter Moon is Sunday April 26. Venus is prominent in the twilight evening sky. Mars is lost in the twilight. Jupiter is the brightest object in the evening sky once Venus has set. The Moon visits Jupiter on the 26th. Saturn is in the head of the Scorpion and now visible in the evening. Mercury is lost to view. Lyrid Meteor shower morning 23rd.

The First Quarter Moon is Sunday April 26. The Moon is at apogee, when it is furthest from Earth, on the 29th.

Evening sky on  Saturday April 21 looking west as seen from Adelaide at 18:30 (6:30 pm) ACST in South Australia.  Venus is obvious in the early evening sky in line with the bright star Aldebaran. Similar views will be seen elsewhere at the equivalent local time (click to embiggen).

Venus is easy to see above the western horizon in the twilight. At nautical twilight, an hour after sunset, it is around two hand-spans above the horizon, and still visible at astronomical twilight.

During the week Venus heads away from the Hyades cluster and Aldebaran towards the stars Castor and Pollux, heading for a meeting with Jupiter later next month..

Mars  is lost in the twilight.

Evening sky on Sunday April 26 looking north-west as seen from Adelaide at 20:00 ACST showing Jupiter and the Moon.  The inset shows Jupiter's Moons at this time. Jupiter is the brightest object above the north-western horizon once Venus has set. (click to embiggen).

 Jupiter  is easily seen  in the evening sky. It is the brightest object above the northern horizon when twilight ends, and continues into the north-western sky as the night goes on. It is between the bright star Regulus in the sickle of Leo (this forms the head of the constellation of the  Lion) and Pollux in Cancer. It is also not far from the rather nice Beehive cluster in Cancer, and looks very good in binoculars.

Jupiter was  at opposition, when it is biggest and brightest in our sky, on 7 February, but it will be an excellent object for many weeks to come.  Jupiter is visible for most of the night, setting just after midnight, and is high enough for telescopic observation once twilight is over. Jupiter's Moons will be putting on a good display in both binoculars and small telescopes.

Evening sky on Saturday April 25 looking east as seen from Adelaide at 22:00 ACST.  Saturn is now easily visible above the horizon. The inset shows the telescopic view of Saturn at this time. (click to embiggen).

Saturn is now easily visible around 9 pm near the head of the constellation of the Scorpion not far from the bright red star Antares. The sight of the distinctive constellation of the Scorpion curled above the horizon, with bright Saturn in its head, is very nice indeed.

While Saturn is  readily visible from around 21:00, it is best for telescope observation from around 22:00 into the morning hours.

Mercury is low in the western evening sky, but is difficult to see in the twilight.

The morning sky looking north as seen from Brisbane at 5:00 am AEST on April 23. The Lyrid radiant is marked with a yellow cross. Similar views will be seen elsewhere at an equivalent local time the radiant will be higher in northern Australia, and lower in southern Australia (click to embiggen). 

The Lyrids, the debris of comet C/1861 G1 (Thatcher) are a weak but reliable shower that occurs every year between April 16- April 25, with the peak this year around 24 hrs UT on April 22 .

That's  around 10 am 23 April in east coast Australia, but as the radiant doesn't rise until 1 am, the best time to view the Lyrids in Australia is from 4 am on the 23rd. 

The predicted ZHR this year is 18 meteors per hour. This means that under ideal conditions, you will see a meteor on average about once every three minutes. This can be as interesting as watching paint dry. Also, while that meteor every three minutes is the average, meteors are like buses, you wait for ages and then a whole bunch turn up. In Australia, the rate is even less, around 6 meteors an hour in Northern Australia. For southern Australia, the rate is even lower.

This is Global Astronomy Month. See the Astronomers Without Borders site for a rundown of what's on. 
There are lots of interesting things in the sky to view with a telescope. Especially with Jupiter just past opposition and Saturn rising. 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 AEDST. 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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