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Posted: July 29, 2008 On 1 August there will be a total eclipse of the Sun visible from Canada, northern Greenland, Svalbard, the Barents Sea, Russia, Mongolia and China, but you don’t need to travel miles to see a partial eclipse because one-third to one-tenth of the Sun will be obscured from view right across Great Britain. Total solar eclipses take place when the Earth, Moon and Sun are perfectly aligned and the shadow of the Moon falls upon the surface of the Earth. At mid-eclipse, observers within the lunar shadow see totality, where the silhouette of the Moon completely covers the Sun for several minutes, revealing the outer solar atmosphere or corona. Away from the path of the total eclipse the Sun is only partly obscured by the Moon, but still offers a fantastic observing opportunity.
Overview of the 2008 solar eclipse path. The dark blue strip shows locations where totality will be experienced and the red dot is where the eclipse will be of greatest duration (2 minutes and 27 seconds). Areas covered by the light blue grid will experience a partial solar eclipse. Image: NASA/ Fred Espenak. At its broadest, the lunar shadow is only 237 kilometres wide but the shadow describes a path thousands of kilometres long, traced out as the Earth rotates, allowing observers all over the world from Canada to China to observe the eclipse. For observers within this 237 kilometre wide corridoor, totality will last for around two minutes, but observers away from the centre of the track and at either end will see a significantly shorter event.
The start, mid-point and end times of the partial solar eclipse from a selection of UK cities, along with the area of the Sun that will be obscured. All times are BST. Although eclipses of the Sun are spectacular events you should NEVER look directly at the Sun with your naked eye or through a telescope as this can cause permanent damage to your eyes. There are a number of ways to safely observe the Sun, such as buying purpose designed solar eclipse glasses, or solar filters from reputable astronomy outlets that can be attached to your telescope. The only other safe ways to observe the Sun is to use a pin hole or telescope to project the Sun’s image onto card. To do this you will need a small refractor mounted on a tripod with a low power eyepiece, and a white screen set at about 45 degrees from the ground to project the image onto. To find the Sun DO NOT try to observe it through your telescope or finderscope. Instead, look at the where the shadow of the telescope tube falls onto the white screen; where it forms the smallest possible circle the solar disc will shine on the card. If you then put a shield (i.e. another piece of card) around the telescope tube you can create a dark shadow onto which the bright solar disc is projected.
To safely observe the partial solar eclipse this Friday, use a small refracting telescope to project the solar disc onto a piece of white card. Image: Martin Mobberley. For more information about the solar eclipse, and also the lunar eclipse occuring on the 16 August, see the current issue of Astronomy Now magazine. There is also detailed information at the NASA Eclipse Website, which will include live coverage of the solar eclipse on 1 August. |
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