Northern Spain will briefly turn dark Wednesday as the Moon completely blocks the Sun in a rare total solar eclipse — the first visible from mainland Europe since 2006.

The eclipse's "path of totality" will cross parts of Russia, Greenland, Iceland, Spain and northeastern Portugal.

Where to see it

In Spain, the eclipse will move roughly from Oviedo in the north to Mallorca. The total eclipse will occur shortly before sunset and last less than two minutes.

In Burgos, darkness will last one minute and 48 seconds.

A partial eclipse lasting about one hour and 45 minutes will be visible across much of Europe, Canada, the northern United States and northwest Africa.

Why it happens

A solar eclipse occurs when the Moon passes directly between the Sun and Earth, casting a narrow shadow over Earth.

The Moon appears large enough to completely cover the Sun because it is about 400 times smaller than the Sun but also about 400 times closer to Earth.

How rare is it?

Solar eclipses occur roughly once or twice a year, but the narrow path of totality means a particular location may wait centuries to experience one.

The next total solar eclipse will cross southern Spain, northern Africa and the Arabian Peninsula on Aug. 2, 2027, lasting up to six minutes and 23 seconds.

Protect your eyes

Never look directly at the Sun during an eclipse. Experts recommend eclipse glasses meeting the ISO 12312-2:2015 standard.

Even during a partial eclipse, sunlight can cause serious and potentially permanent eye damage.