The solar eclipse of 4 January 2011

21 December 2010

On the morning of Tuesday, 4 January 2011, an eclipse of the Sun will be widely visible across Europe and as far east as India. People in Western Europe will find the Sun already eclipsed as the day begins, with the eclipse lasting about 80 minutes more. Even at a maximum, the eclipse will be only partial, with some of the Sun always visible. Because the 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, 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 millimetres 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 4 January, the Moon will gradually cover the Sun, over a period of about 3 hours. At maximum, the eclipse will be at the horizon at sunrise in England, with 75% of the Sun's diameter covered, and then gradually emerge over the next hour and 20 minutes. In Paris or Berlin, 80% of the Sun will be covered near sunrise. Farther east, the Sun will be a bit higher in the sky at maximum, 22° high with 67% covered in Athens. In Israel and Egypt, the Sun will be 33° high with over 55% coverage at maximum.



Prof. Jay M. Pasachoff (

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