Observers catch rare glimpse of Mercury passing the Sun

Astronomers and space enthusiasts have watched as Mercury made a rare transit of the Sun.

The smallest planet in the solar system could be seen as a tiny black disc moving across the glowing orb, starting at just after 12.35pm today.

Members of the public were urged to join Astronomy Ireland at its headquarters in Blanchardstown, Dublin, to witness the occasion safely.

They had set up special telescopes and streamed the transit from observatories around the world.

The last time Mercury passed the Sun this way was in 2016, but the next is not due until 2032.

That's all, folks! Mercury has left the disk of the Sun, completing the transit. The next Mercury transit is in 2032 — so in the meantime, you can read up on @NASAUniverse's TESS mission, which uses transits in other star systems to look for exoplanets! https://t.co/2NlnHKzBFn pic.twitter.com/zRLdYnHiaz

— ARCHIVED - NASA Sun & Space (@NASASun) November 11, 2019

Nasa revealed some of the first images of the transit, taken from its satellite monitoring the sun.

The entire event was visible from the eastern United States and Canada, the south-western tip of Greenland, most of the Caribbean, Central America, the whole of South America and some of west Africa.

Happening Now: The planet Mercury passes directly in front of the Sun! ✨

This view from Washington, DC this morning. See more #MercuryTransit views: https://t.co/qESVj1SnPO

(for this image on Flickr: https://t.co/ED2WRybens ) pic.twitter.com/VNhrx9YQ9g

— NASA HQ PHOTO (@nasahqphoto) November 11, 2019

In Europe, the Middle East and most of Africa, the Sun set before the transit ended, so the latter part of the event was not visible.

Every 88 years Mercury completes each orbit around the Sun, and it passes between the Earth and sun every 116 days.

Because the planet’s orbit around the Sun is tilted, it normally appears to pass above or below our nearest star.

These views of the #MercuryTransit, now in progress, came from @NASASun’s Solar Dynamics Observatory. See the latest images as they come down from space: https://t.co/DbwwQc3SUO pic.twitter.com/bA3Uvxe0jD

— Cassini (@CassiniSaturn) November 11, 2019

A transit can only take place when the Earth, Mercury and the Sun are exactly in line in three dimensions.

Looking at the Sun without appropriate protection, either during the transit or at any other time, can cause serious and permanent damage to the eyes.