Eyes Up - September 2009
The monthly guide to what's in the sky over Perth for September 2009, written for the Scouts WA newsletter.
During September the days continue to get longer. By the 30th, the Sun rises at 5.56am and sets at 6.18pm. The Moon is full on the 5th and new on the 19th. Jupiter continues to be the most obvious of the planets, rising before dark and clearly visible high in the sky all evening, setting in the early hours of the morning. During the first half of the month Mercury is visible in the western sky for an hour or so after sunset; it will be faint so look carefully! Venus continues to be a morning object, visible in the east before sunrise.
A rare event happens this month: for a short time, the rings of Saturn will apparently disappear! The rings are 280,000km across but only 20km in thickness and are not solid but are made up of lumps of ice and rock. While they might appear to vanish, the rings do still exist, but they are so thin that when they are viewed exactly edge-on from Earth they cannot be seen. Imagine how hard it would be to see a CD held edge-on from several kilometres away! This phenomenon happens roughly every 14 or 15 years and only lasts a short time. If you have access to a telescope, try and take a look at Saturn - you can find it low in the western sky in the early evening. The rings will disappear on September 4th, and reappear on the 5th.
August saw one of the best meteor showers in the Northern hemisphere, the Perseids. The next good shower visible from the Southern hemisphere is known as the Orionids, so-named because they appear to travel outwards from the constellation of Orion. This shower peaks in October, but begins at the very end of September, so keep your eyes peeled for shooting stars if you are camping towards the end of the month.
The timings are correct for metro areas and will be slightly different for country observers and those in other states.