A solar eclipse is one of nature's most jaw-dropping spectacles: the Moon slides directly between Earth and the Sun, and for a few surreal minutes, day turns to twilight.
With a total solar eclipse crossing Iceland and Spain on August 12, 2026, here are the fact-checked essentials — including how to watch one safely.
A solar eclipse happens when the Moon passes directly between the Earth and the Sun, casting its shadow onto Earth's surface.
There are four types: total, partial, annular (a 'ring of fire'), and the rare hybrid eclipse that shifts between total and annular along its path.
Total solar eclipses are possible because of a cosmic coincidence: the Sun is about 400 times wider than the Moon but also about 400 times farther away, so the two appear nearly the same size in our sky.
During totality, the Sun's faint outer atmosphere — the corona — becomes visible as a shimmering halo, something normally impossible to see.
The next total solar eclipse, on August 12, 2026, will be the first visible from mainland Europe since 1999, with a path of totality crossing Siberia, eastern Greenland, western Iceland, and northern Spain.
The maximum totality for the August 12, 2026 eclipse lasts about 2 minutes and 18 seconds, and in Spain and Portugal it occurs low in the sky near sunset.
Totality is only ever visible along a narrow path, typically about 100 miles wide, while a much larger region sees a partial eclipse.
It is never safe to look at a partial or annular eclipse with the naked eye — you must use certified eclipse glasses meeting the ISO 12312-2 standard, not regular sunglasses.
The only time it is safe to look without eye protection is during the brief total phase, when the Sun's bright disk is completely covered.
Just before and after totality, sunlight streaming through valleys on the Moon's edge creates sparkling points called Baily's beads, and a single bright flash known as the 'diamond ring.'
During totality, temperatures can drop noticeably, stars and planets appear, and confused animals may behave as if night has fallen.
A solar eclipse can only occur at a new moon, when the Moon is between Earth and the Sun.
Eclipses don't happen every month because the Moon's orbit is tilted about 5 degrees relative to Earth's orbit around the Sun.
Every place on Earth sees a total solar eclipse only about once every 375 years on average, which is why eclipse chasers travel the globe.
The 2017 'Great American Eclipse' was watched by an estimated 215 million U.S. adults, and the April 2024 eclipse crossed Mexico, the U.S., and Canada.
Ancient cultures often saw eclipses as omens; a solar eclipse in 585 BC reportedly halted a battle between the Lydians and Medes, one of the earliest datable historical events.
Studying the Sun's corona during the 1868 total eclipse led to the discovery of helium — an element found in the Sun before it was found on Earth.
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