Total Solar Eclipse to Occur on August 1, 2008

Those who have been waiting two years for a total solar eclipse of the sun can rejoice when the next one occurs on August 1, 2008. The path of the moon's umbral shadow begins in Canada and extends across northern Greenland, the Arctic region, central Russia, Mongolia, and China. A partial eclipse will be seen within the broader path of the moon's penumbral (partially shaded outer region) shadow, which includes northeastern North America, most of Europe, the Middle East and western parts of Asia.

This illustration is not to scale and shows a general total solar eclipse, not the August 2008 eclipse.

The longest duration of the solar eclipse’s totality will occur in Russia and last for about two minutes and 27 seconds at about 10:22 Coordinated Universal Time (UTC) on this day. Total solar eclipses happen about once every 1.5 years. Shadow bands are often seen on the ground as totality approaches.

Traveling with the Solar Eclipse in August 2008

According to Philip Harrington, the author of Eclipse! The What, Where, When, Why & How Guide to Watching Solar and Lunar Eclipses, the total solar eclipse will begin in Canada and finish in north-central China. An umbra refers to the fully shaded inner region of a shadow, especially the area on the earth or moon experiencing totality in an eclipse. The moon’s umbra is first cast on earth in the far northern corner of the Northwest Territories in Canada. Though the central shadow narrowly misses Cambridge Bay on Victoria Island and Resolute on Cornwallis Island, its edge just nips the town of Alert on Ellesmere Island, giving residents 40 seconds of early morning totality.

Cross the Atlantic north, the eclipse’s path skips across Greenland’s northernmost coast and comes within about 720 kilometers (450 miles) of the North Pole before heading southward toward more moderate climes. Totality of the eclipse passes by Svalbard in Norway and touches Russia’s Franz Josef Land island group before cutting across Novaya Zemlya on its way to mainland Asia.

The umbra first touches the Russian coast of the Yamal Peninsula. The solar eclipse occurs closer to the inland, producing about two minutes and 27 seconds of totality and reaches near the town of Nadym, inland from the boot shaped Gulf of Obskaja. Continuing to hook towards the southeast, the central path passes near Novosibirsk where totality lasts about two minutes and 18 seconds. The path then enters western Mongolia, with the towns of Olgij and Bulgan seeing about two minutes of a total eclipse. A total eclipse then occurs in north-central China before leaving earth just north of the cities of Lanzhou and Xian. A partial eclipse will be seen throughout northeastern North America, most of Europe, the Middle East and western parts of Asia.

The above image shows a general total solar eclipse. ©iStockphoto.com/Simon Podgorsek

How Does a Total Solar Eclipse Work?

A total solar eclipse occurs when the moon completely covers the sun, as seen from earth. Total solar eclipses happen because the sun is near one of the nodes of the lunar orbit, and the moon is at perigee (the point in the orbit of the moon or a satellite at which it is nearest to the earth) at this node at the same time.

During totality the photosphere, a blindingly bright surface of the sun that is visible on a sunny day, is hidden and allows other normally invisible features of the sun to be seen. Surrounding the photosphere is a thin, deep red layer of the sun called the chromosphere. Measuring a few thousand kilometers thick, the chromosphere is seen for only a few seconds at the beginning and end of totality. Flame-like prominences from behind the moon’s silhouette stretch for thousands of kilometers into space. The white corona encircles the eclipsed sun and extends the sun’s diameter several times.

Timing and location are important to view a total solar eclipse. By the time it reaches earth, the moon’s umbra is about 270 kilometers (170 miles) across at its widest so a chance that the umbral shadow passes over at a particular spot is slim. A total solar eclipse at one given point on earth occurs on average only once in about 360 years.

The sun’s diameter is about 1,392,000 kilometers (844,900 miles) and the moon’s diameter is about 3476 kilometers (2160 miles) in comparison. This works out to be a ratio of approximately 400 to one – the sun is about 400 times larger in diameter than the moon. At the same time, the sun is about 149,600,000 kilometers (93,000,000 miles) from earth while the moon is 384,500 kilometers (240,000 miles) away. As a result, the moon and sun each appear the same size in the sky – about half a degree. When a solar eclipse occurs, the moon appears to cover the sun’s surface while exposing the sun’s normally invisible chromospheres. An eclipse’s duration is longer if the moon-to-sun ratio is greater.

Interesting Fact

Totality of a solar eclipse can last about seven minutes and 31 seconds but these eclipses are rare. It is predicted that totality during the solar eclipse will last for seven minutes and 14 seconds in the year 2150, which is longer than any total solar eclipse since the ninth century AD. A period of totality is normally shorter than five minutes.