Nepali Times
Star Gazing
September sky


KEDAR S BADU


In September we have the autumn equinox and the Harvest Moon, while mighty Jupiter dominates the evening skies. But before that, let's talk about the stars.

In September, the sky moves to its autumn phase, revealing another set of stars and constellations that were hidden for some time behind the glare of the Sun. In the evening, a couple of hours after sunset, you will be able to see the constellations of Pisces, Aquarius, Capricornus, Sagittarius and Scorpius from east to west along the Zodiac. The brightest of these are Sagittarius and Scorpius, which are easily identifiable in the south and south-western skies.

Can you see the bright, star-like object in Sagittarius the Archer? This is Jupiter, the largest planet. If you have at least a four-inch telescope, you can see its four main moons?the Galilean satellites. Sagittarius lies towards the centre of the Milky Way, so with a telescope you can find many other colourful nebulae and star clusters nearby.

Just west of Sagittarius is the brilliant constellation of Scorpius the Scorpion with the red supergiant Antares at its centre (see star chart), 400 times the size of the Sun. In the evening, the Summer Triangle marked by Vega, Deneb and Altair lies directly overhead.

This year the autumnal equinox, signalling the end of summer, occurs on 22 September at 2131 hours Universal Time. At that point, night and day are of equal length. After this the Sun moves into the southern half of the sky and for the next six months the nights are longer than the days.

Early in the month, Mercury will be setting soon after sunset and will reach its greatest eastern elongation on 11 September. Using binoculars, look out for the gathering of Mars, Venus and Mercury on the western horizon an hour after sunset on 11 September. Jupiter, high in the southern sky during the month will be easy to spot. On 9 September, the Moon and Jupiter come close together and should fit into the same field of view of a pair of binoculars.

Saturn is directly behind the Sun on 4 September but by the end of the month should be emerging into the dawn sky. Look for it in the east just as the sky is beginning to brighten around 6AM.

The Harvest Moon occurs on 15 September. It is so named because its light helps farmers to continue harvesting their fields after sunset. Another attraction in September is the meeting of the Pleiades star cluster (the Seven Sisters) with the waxing gibbous Moon in the early hours of 20 September.

There are no major meteor showers in September, though there are various minor showers producing a few meteors an hour from radiants in Cassiopeia, Auriga, Aquarius and Pisces. But this is generally a good time of year for seeing sporadic meteors, which may appear at any time, in any part of the sky.



LATEST ISSUE
638
(11 JAN 2013 - 17 JAN 2013)


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