Mercury has passed directly between the Earth and Sun for the first time in a decade. The smallest planet in our solar system could be seen as a tiny black dot slowly inching its way across the face of the glowing star.
The celestial event is rare – it happens only about 13 times a century.
The next transit won’t happen until 2019 – and then in 2032 after that.
The entire seven-and-a-half-hour trek was visible from eastern US and Canada, as well as Western Europe, West Africa and most of South America.
In Eastern Europe, the Middle East, central Asia and most of Africa, sunset meant the show finished early.
Australia, New Zealand and Papua New Guinea missed out altogether.
But many stargazers watched Monday’s event on various live streams, such as those from the European Space Agency or NASA.
It was also broadcast on screens at a number of public locations across the world, including at the Royal Observatory Greenwich.
Astronomers also gathered at the Observatory to take advantage of the 28 inch-wide Great Equatorial Telescope, which is the largest lensed telescope in the UK.
The last time it was turned towards the Sun was 1927. It used a new solar filter to make the viewing possible.
At one time the passing of Mercury in front of the Sun was a useful scientific opportunity because it allowed astronomers to measure distances in the solar system.
Jim Green, director of NASA’s planetary science division, viewed his first transit of Mercury 46 years ago.
“What happens during a transit is really all about perspective,” said
He said scientists used Monday’s transit to learn more about Mercury’s very thin atmosphere.