While the path of totality will be limited to a narrow corridor, millions of people across the Northern Hemisphere will also be able to see a partial eclipse.
According to NASA, the total solar eclipse will pass over Greenland, Iceland, northern Russia, the Atlantic Ocean, Spain and a small part of Portugal. Partial phases of the eclipse will be visible across much of Europe, Canada, northwestern Africa and parts of the northern United States.
For many observers in mainland Europe and Africa, the eclipse will coincide with sunset, creating the rare spectacle of a sunset eclipse.
NASA to livestream the eclipse
Those unable to witness the eclipse in person can watch it online. NASA will livestream the total solar eclipse beginning at 1:15 pm EDT (10:45 pm IST) on August 12 at https://www.nasa.gov/live.
Where will the eclipse be visible?
According to NASA, the path of totality on August 12 will pass over Greenland, Iceland, northern Russia, the Atlantic Ocean, Spain and a small part of Portugal. In northern Russia, totality will occur around midday, while observers in Greenland and Iceland will witness it during the late afternoon or early evening.
In Spain and the northwestern tip of Portugal, the Sun will be completely eclipsed shortly before sunset, creating a rare total solar eclipse.
For many places along the path of totality, the Moon will completely cover the Sun for less than two minutes. Those near the centre of the eclipse path in Greenland, Russia and parts of the North Atlantic may experience a slightly longer totality, though it will still last under two-and-a-half minutes.
What about the rest of the world?
Outside the path of totality, millions of people will witness only a partial solar eclipse. NASA says the partial eclipse will be visible across parts of the northern United States, Canada, Europe and northwestern Africa, with the extent of coverage varying by location.
In the United States and southern Canada, the Moon will appear to take only a small ‘bite’ out of the Sun. Areas closer to the path of totality, including much of Europe and parts of northwestern Africa, will see a much larger portion of the Sun covered.
How to watch it safely
NASA says viewers can remove their eclipse glasses only during the brief period of totality, when the Moon completely blocks the Sun’s bright face. Before and after totality, and throughout the event for everyone viewing a partial eclipse, proper eye protection must be worn.
Observers should use ISO 12312-2 certified eclipse glasses, a handheld solar viewer or a properly fitted solar filter for telescopes, binoculars and cameras. Regular sunglasses are not safe for viewing the Sun. Those without eclipse glasses can safely watch the event using an indirect viewing method, such as a pinhole projector.
What is a total solar eclipse?
A total solar eclipse occurs when the Moon passes between the Sun and Earth, completely blocking the Sun’s face. People located in the centre of the Moon’s shadow experience totality, during which the sky darkens as though it were dawn or dusk.
If weather conditions are favourable, observers can also see the Sun’s corona, its outer atmosphere, which is usually hidden by the Sun’s bright surface.
What are the stages of a total solar eclipse?
According to NASA, a total solar eclipse unfolds in several stages, each marked by a distinct visual phenomenon.
The eclipse begins with the partial phase, when the Moon starts moving across the Sun, making it appear as a crescent. Just before and after totality, observers may also notice shadow bands, fast-moving dark bands separated by white spaces that can appear on the ground or the sides of buildings. According to NASA, these bands are often difficult to photograph.
As the Moon covers more of the Sun, Baily’s Beads become visible. These are light rays from the sun shining through valleys along the Moon’s edge. They are followed by the Diamond Ring effect, when only a single bright point of sunlight remains, creating the appearance of a sparkling diamond set against a ring.
The most dramatic stage is totality, when the Moon completely blocks the Sun’s bright face. During totality, observers may also see the chromosphere, which appears as a thin pink rim around the Moon, and the corona, the Sun’s outer atmosphere, visible as streams of white light. Once totality ends, the eclipse progresses in reverse.