Look out for an odd eclipse

Autumn starts this year with a brief glimpse of an unusual type of solar eclipse. This Saturday, the sun will rise with the moon partly covering the sun's face.

All parts of New Zealand will see a partial solar eclipse but further to the east over the Pacific and in the northern parts of South America it will be seen as a hybrid annular-total eclipse.

An annular eclipse occurs when the moon's apparent diameter is just a little less than that of the sun, leaving a bright annular ring of light. A total eclipse occurs when the sun's light is completely blocked by the moon.

A solar eclipse is usually either annular or total but this one will actually be a combination of the two. Along the narrow path of totality, the eclipse will change from being annular to total and finally back to being annular again.

New Zealand is close to the start of the eclipse path. In Auckland the sun will rise at 6.45am with the moon obscuring 57 per cent of its face. By 7.50am the eclipse will be all over with the sun still just 12 degrees above the horizon. Therefore, in order to view this eclipse, a clear eastern horizon is required - preferably with a clear sea view.

Warning: Remember that it is extremely dangerous to view the sun directly with any optical instrument. Severe damage to the eyes will result.

Of the bright planets, Saturn is in Gemini and due north at sunset but it will become increasing difficult to see as the month proceeds.

Jupiter is at opposition on April 4 and therefore rises in the east at sunset. This date corresponds to the closest distance between Earth and Jupiter (668 million kms) so it is the best time of the year to view the planet through a telescope. Jupiter appears as a brilliant yellow object, much brighter than any star. It will remain well-placed for viewing over the next few months and it will be one of the most popular attractions at the Stardome. Mars is in Capricornus and rises at about 2am. The other naked-eye planets, Venus and Mercury, are too close to the Sun to be seen.

The prominent summer constellations of Orion, Taurus and Gemini are being replaced by the autumn constellations of Leo and Virgo. In the south, Crux (The Southern Cross) is rising through the early evening and reaches its highest point due south at midnight. This is definitely the time of year to explore this rich region of the Milky Way with binoculars before the cold winter evenings arrive.

* Dr Grant Christie is an astronomical researcher and former chairman of the Auckland Observatory and Planetarium Trust Board.

* The Stardome observatory is open Wednesday to Saturday. Phone (09) 624-1246.