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24 November 2011

Cape Town to see solar eclipse

On Friday 25 November, a solar eclipse will sweep across the southern part of the world. Only viewers close enough to Antarctica such as those living in Cape Town will see the sun eclipsed.

On Friday, November 25, a solar eclipse will sweep across the southern part of the world, with the Moon covering about 80% of the Sun at the south pole. Only viewers close enough to Antarctica - in Cape Town, South Africa, near sunrise, and in the Australian island of Tasmania and the South Island of New Zealand near sunset - will be able to see the Sun eclipsed. Even at its maximum on Earth, the eclipse will be only partial, with some of the everyday sun always visible. The central part of the shadow will pass 330 km below the south pole; 90% of the Sun will be covered at the part of Antarctica south of Patagonia, South America. Because the everyday sun is too bright to look at safely, special solar filters or projection methods should always be used to protect the eyes.

Prof. Jay Pasachoff of Williams College in the United States, the Chair of the International Astronomical Union's Working Group on Eclipses, will be viewing his 54th solar eclipse. He reports that "eclipses have inspired many astronomers and scientists as children, so it is wonderful when students and people of all ages have a chance to see an eclipse. But it is important to view it safely. Whenever the ordinary Sun is visible, even only part of it, you should not stare at it. Special solar filters are available cheaply, or dense welders' glass will do. Another method of seeing that the Sun is eclipsed is to punch a hole a few millimeters across in a piece of cardboard and hold it up to the Sun while you face away from the Sun and see the Sun's image projected on the ground or onto another piece of cardboard. This method is called projection with a pinhole camera. It is rare that haze or clouds are sufficient to reduce the Sun's intensity enough that one can see a partially covered Sun safely."

On November 25, the Moon will gradually cover the Sun. In Cape Town, South Africa, the eclipse will take place over a period of about 80 min about an hour after sunrise, from 4:28 to 5:18 UT (6:28 to 7:18 local time), with a maximum coverage of 10% of the Sun's diameter, and with the Sun rising from 10° to 20° above the horizon. Amanda Gulbis of the South African Astronomical Observatory and Williams College alumnus Darik Velez will be observing from Cape Town. In Invercargill, New Zealand, the eclipse will take place over a period of 73 minutes, from 7:03 UT to 8:17 UT (8:03 pm to 9:17 pm), with a maximum coverage of 30%, and with the Sun descending from 9% above the horizon to 1% below the horizon, though the atmosphere may bend the sunlight enough to make the end of the eclipse visible at the horizon. In Lauceston, Tasmania, the eclipse will take place over a period of about 24 minutes, from 7:39 to 8:03 UT (6:39 to 7:03 pm), with a maximum coverage of only 2% of the Sun's diameter, and with the Sun moving lower in the sky from 17° to 12° above the horizon. In Hobart, Tasmania, the eclipse will take place over a period of about 38 minutes, from 7:30 to 8:08 UT, with a maximum coverage of almost 6% of the Sun's diameter, and with the Sun moving lower in the sky from 19° to 12° above the horizon.

- Gadget