What is an eclipse?

An eclipse in astronomy happens when a body comes between us and a light emitter, so that we can no longer see the source.

For example, when the Moon aligns between us and the Sun, it blocks out sunlight and casts a shadow over part of the Earth.

An eclipse can also occur when a body comes between a light source and the body that the light is illuminating, so that we no longer see the illuminated body.

What is a total solar eclipse?

An eclipse of the Sun occurs when the Moon comes directly between the Sun and the Earth so that the Earth lies in the shadow of the Moon.

Because the Moon is much smaller than the Earth, its shadow only covers a small part of the Earth's surface. That means that a solar eclipse can only be seen from a certain region of the Earth.

A total solar eclipse can be viewed from the darkest part of the Moon's shadow (its umbra); areas covered by partial shade (its penumbra) witness a partial eclipse.

Watch more in this film series

What is an annular eclipse?

When the Moon is not at its closest to the Earth, its apparent diameter is less than that of the Sun. Even where the Moon's disk obscures the Sun centrally, the outer ring of the Sun's disk is still visible. This is called an annular eclipse.

What is a lunar eclipse?

An eclipse of the Moon occurs when the Earth lies directly between the Sun and the Moon and the Moon lies in the shadow of the Earth. During a total eclipse, the Moon does not disappear entirely but turns a deep, dark red. The Moon is illuminated by light that has passed through the Earth's atmosphere and has been bent back towards the Moon by refraction.

Find out more about lunar eclipses

When is the next solar eclipse in the UK?

There are between two and five solar eclipses each year with a total eclipse taking place every 18 months or so.

Total solar eclipses are seen every 400 years from any one place on the surface of the Earth.

The Royal Observatory will be broadcasting the next solar eclipse in the UK live on Facebook and YouTube.

Solar eclipses in the UK

Date Eclipse type
10 June 2021 Partial
25 October 2022 Partial
23 September 2090 Total

Solar eclipses worldwide

Date Eclipse type Location
10 June 2021 Annular Much of Europe, Asia, North and West of Africa, much of North America, the Atlantic and the Arctic
4 December 2021 Total Antarctica. Partial eclipse may be visible in parts of southern Africa, Australia and South America

When was the last total solar eclipse in the UK?

The last time the path of an eclipse's totality went over the UK was in 1999. This was one of the most viewed total solar eclipses due to its path falling on areas of high population density.

However, many areas of Western Europe were affected by poor visibility due to clouds. In some places, the clouds frustratingly parted after the eclipse had passed, but others were luckier with the clouds parting just in time.

Many people went to view the eclipse in Cornwall, the only place in the UK to witness totality, with the BBC broadcasting from Cornwall's western end where the eclipse would come first.

How can I see an eclipse?

As always, with any observing event involving the Sun, it should never be looked at directly without the appropriate filters.

The Royal Observatory will be live streaming the next solar eclipse in the UK on YouTube and Facebook, featuring state-of-the-art telescopes and expert commentary from Observatory astronomers.

Find out more

If you want to look at an eclipse directly and safely there are a couple of options.

  1. Check and see if your local astronomical society is hosting a solar eclipse event as they will have many instruments specifically for solar viewing or telescopes that have been fitted with the right filters.
  2. If you can’t get out to these events and still want to look at the eclipse directly, you can purchase solar eclipse viewing glasses. These must be the real deal, not 3D glasses or anything similar.
  3. The safest, cheapest and arguably the most convenient way to view the event is by pinhole projection. This is extremely safe as there is no need to look directly at the Sun and the display can be shared by a few people together.

How to make a pinhole projector

  • Make a hole in a piece of card.
  • Hold the card up to the Sun, and hold a piece of paper behind the card.
  • See the shape of the Sun projected onto the paper - a small version of the event!

Eclipses in myth and history

Ancient myths from many cultures around the world have explained eclipses as a time when an animal or demon eats the Sun or Moon.

Even today, modern superstitions exist surrounding eclipses, with some believing that they could harm pregnant women. Scientists have debunked these modern superstitions; the only precaution you need to take is protecting your eyes when viewing the Sun.

Christopher Columbus's voyage. The Indians astonished at the Eclipse of the Moon foretold by Columbus. Engraved for Drake's Voyages
  • For the Ancient Greeks, an eclipse was a bad omen, spelling death and destruction caused by an angry god.

  • The Pomo, an indigenous people from the north western United States, tell a story of a bear who started a fight with the Sun and took a bite out of it.

  • When on an island northeast of Cuba, Christopher Columbus correctly foretold a total lunar eclipse, using his knowledge to play on the native people’s superstitions and persuade them to give him and his men food.

  • Eclipse has been a popular name for ships in the Royal Navy, with eight in total taking the HMS Eclipse title. The first of these ships was a 12-gun, 169-ton gunboat launched at Blackwall on 29 March 1797. The most recent was an E-class destroyer launched at Denny on 12 April 1934 and sunk by a mine in the Aegean Sea on 24 October 1943. This is its boat badge, held in our collection at the National Maritime Museum. 

Official boat badge of HMS Eclipse 1934
Royal Observatory

Visit the Royal Observatory

Discover the home of Greenwich Mean Time and find out more about the history of astronomy