Venus is set to move across the face of the Sun as viewed from Earth in a more than six-and-a-half-hour transit, which starts just after 22.00 GMT on Tuesday.
The transit is a very rare astronomical phenomenon that will not be witnessed again until 2117.
Observers will position themselves in northwest America, the Pacific, and East Asia to catch the whole event.
• Times for the start of Venus transit will vary by a few minutes depending on one’s location
• The timings given here are calculated for a viewing position at the Earth’s centre
• Venus is seen to first touch (1) the edge of the Sun’s disc at 22:09 GMT (23:09 BST)
• It is completely on the disc (2) by 22:27 GMT (23:27 BST). The transit lasts over six hours
• Come Wednesday by 04:31 GMT (05:31 BST), Venus is touching the disc’s far side (3)
• At 04:49 GMT (05:49 BST), Venus has left the disc (4). The next transit is on 11 December 2117