August 18, 2017

Get ready! On Monday, August 21, if you live in the United States from Oregon to South Carolina, you will be able to experience one of nature’s most impressive sights–a total eclipse of the sun. Across the United States, large crowds are expected in towns, cities, and campsites along the path of totality for the spectacular celestial show. The path of totality is the narrow swath, about 70 miles (110 kilometers) wide, along which the moon will completely blot out the sun.

A solar eclipse occurs when the moon passes between Earth and the sun, blotting out the sun’s light. This photograph shows a total eclipse, in which the moon completely covers the face of the sun. The sun’s outer atmosphere, called the corona, appears as an irregularly shaped halo of light. Credit:

A total solar eclipse occurs when the Earth, sun, and moon are in nearly a straight line and the moon’s shadow sweeps across the face of Earth. The dark moon appears on the edge of the sun and moves slowly across. At the moment of totality, a brilliant halo flashes into view around the darkened sun. This halo is the sun’s outer atmosphere, the corona. The sky remains blue but darkens dramatically. Some bright stars and planets will become visible and the temperature will noticeably drop. After a few minutes, the sun reappears as the moon continues on its orbit. The period when the sun is totally darkened may be as long as 7 minutes 40 seconds, but it averages about 2 1/2 minutes.

A total eclipse of the sun, as shown here, starts at the left. The moon gradually covers the sun, shown photographed through a filter. At the time of the total eclipse, photographed without a filter, the sun’s corona (outer atmosphere) flashes into view. The sun reappears as the moon moves on. Credit: © Atlas Photo Bank/ Photo Researchers

In the United States, the path of totality will cross 14 states: Oregon, Idaho, Wyoming, Montana, Nebraska, Iowa, Kansas, Missouri, Illinois, Kentucky, Tennessee, Georgia, North Carolina, and South Carolina. This will be the first total solar eclipse to cross the United States from coast-to-coast since June 8, 1918, when a total solar eclipse darkened skies from Washington to Florida. The last total solar eclipse to be seen anywhere in the continental United States was in 1979.

Makanda, a village in southern Illinois just south of Carbondale, will see the longest duration of totality for the eclipse–about 2 minutes and 40 seconds. If you miss out, though, don’t worry. Another total solar eclipse will cross the same area in 2024!

If you are going to view the eclipse, be careful! Looking directly at the sun, even during an eclipse, can severely damage your eyes, even if you are wearing sunglasses. If you wish to look directly at the eclipse you will need “eclipse glasses” which have special solar filters. Make sure that your eclipse glasses are undamaged and meet safety standards. Be careful to look away from the sun when you put your eclipse glasses on and take them off. A total solar eclipse can be viewed safely without protection in the path of totality only during the brief time when the disk of the sun is completely hidden.

More on this story next week!

March 20, 2015

On the first day of spring, darkness crept over much of Europe and parts of Africa and Asia in the middle of the day, and then retreated as quickly as it had come. The moon had briefly blocked out the sun, resulting in a spectacular solar eclipse.

The moon blocks part of the sun during a solar eclipse, as seen over a statue in Saint Petersburg, Russia. Credit: AP Photo

A solar eclipse happens when the moon’s shadow sweeps across the face of Earth. The shadow usually moves from west to east across Earth, and at a speed of about 2,000 miles (3,200 kilometers) per hour. The dark moon appears on the western edge of the sun and moves slowly across the sun.

Most people in Europe and Africa experienced a partial solar eclipse, with the moon only covering part of the sun. A total solar eclipse, wherein the moon covers the entire sun, can be seen only in the path of totality, the path along which the moon’s shadow passes across Earth. The path of totality is never wider than about 170 miles (274 kilometers). For today’s solar eclipse, the Faroe Islands and Svalbard in the North Atlantic Ocean were in the path of totality, treating locals and visitors in those areas to a total solar eclipse.

This solar eclipse was particularly special because it occurred on the same day as the vernal equinox in the Northern Hemisphere. An equinox is either of two moments each year when the sun is directly above Earth’s equator. Because cycles in astronomy often act within other cycles, the next eclipse on an equinox will come relatively soon: March 20, 2034.

Other articles:

• NASA: Solar Eclipse page

• Reading the Sky: Early Places of Astronomy (a Special report)

November 15, 2012

Sky watchers along the northern coast of Australia lined up this week for Earth’s last total solar eclipse until 2015. The eclipse began on November 14 just after dawn (local time there). The event was visible from slivers of Australia’s Northern Territory and state of Queensland, as well as a large, empty stretch of the Pacific Ocean, including the Coral Sea.

The path of the eclipse was far from any large cities. However, tens of thousands of people set up along the Australian coast to get a glimpse of the rare and beautiful event. Still more people took to the ocean on boats and ships to view the spectacle. The last total eclipse on Earth was about two years ago. A partial eclipse was visible across much of the South Pacific, including New Guinea and New Zealand, and parts of South America.

The moon moves to cover the sun during a solar eclipse, above the Blue Mosque in Istanbul, Turkey. (AP/Wide World)

An eclipse is created when the moon passes in front of the sun, blocking the sun’s light from reaching Earth. The event occurs rarely in any given area of Earth. But it occurs someplace on Earth every few years. During an eclipse, the outer atmosphere of the sun, called the corona, can be seen. The corona is hundreds of times as hot as the surface of the sun. An eclipse is beautiful to witness but can be dangerous. Direct sunlight is very powerful and can damage the eyes if viewed for any amount of time.

The next total solar eclipse will occur in March 2015 and will be visible in the North Atlantic region, including Norway’s Svalbard islands. A partial eclipse will occur in parts of Africa and the Atlantic Ocean in November 2013.

Additional articles in World Book:

• Baily’s beads
• Astronomy (1923) (a Back in Time article)
• Astronomy (1955) (a Back in Time article)
• Reading the Sky: Early Places of Astronomy (a Special Report)