Total solar eclipse on August 12: Which countries will be able to see it?

Day will briefly turn into night across a swathe of northern Spain on August 12, when the Moon will completely cover the Sun during a rare total solar eclipse.

Here is what you need to know about the total eclipse, which is the first visible in mainland Europe since 2006.

Eclipses happen when the Moon passes directly between the Sun and Earth, casting a narrow band of shadow across our planet.

It creates a strange twilight during which temperatures drop, shadows appear at strange angles and some animals go to sleep.

These odd phenomena convinced ancient cultures that eclipses were signs of the apocalypse — or messages from the gods.

"Even though the Sun is about 400 times bigger than the Moon, it is also about 400 times farther away," the US space agency says.

This means that for people standing in the right spot, the Moon totally covers the Sun -- revealing its outer atmosphere called the corona.

The "path of totality", as it is known, will then cross over Greenland, Iceland, Spain and the northeastern tip of Portugal.

The eclipse will cross over areas that have been hit by devastating fires in Spain, which scientists say were made more likely by human-driven climate change.

Nasa will be live-streaming the event on August 12, starting at 1:15pm ET (1715 UTC), so you can watch the eclipse from anywhere.

The northern city of Burgos, for example, will be plunged into darkness for exactly one minute and 48 seconds.

It will last slightly longer in parts of Russia and Greenland, though still under two-and-a-half minutes.

However, partial eclipses — which occur as the Moon starts and finishes crossing the Sun — will last around one hour and 45 minutes.

Partial eclipses will also be visible in most of Europe, Canada, the northern United States and northwest Africa.

One or two solar eclipses occur roughly every year. However the small band of totality means that the same area may wait 400 years before seeing another one.