Astronomers and space enthusiasts watched as Mercury made a rare transit of the sun yesterday.

The smallest planet in the solar system could be seen as a tiny black disc moving across the glowing orb.

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

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 southwestern tip of Greenland, most of the Caribbean, central America, the whole of South America and some of west Africa.

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

Every 88 days Mercury completes each orbit around the sun, and 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.

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