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Observers catch rare glimpse of Mercury passing the sun

Mercury starting its transit of the sun (Nasa/SDO)
Mercury starting its transit of the sun (Nasa/SDO)

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

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

Members of the public wishing to see the special event were urged to join amateur astronomical societies and public observatories across the country to witness the occasion safely.

However, poor weather conditions hampered some efforts to catch the occasion.

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 is 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.

Mercury passing the sun
(Nasa/SDO/PA)

In Europe – including the UK – the Middle East and most of Africa, the sun will set before the transit ends, and so the latter part of the event will not be visible.

Every 88 years 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.

Mercury transits the sun
(PA Graphics)

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.