Stargazers all over the world are setting up special telescopes and passing out cardboard eclipse glasses to view a once-in-a-lifetime celestial cameo - Venus passing in front of the sun.
The transit of Venus is a planetary spectacle that will not occur again until 2117.
Earth's second nearest neighbour will not significantly block the sun's light, but it will give our closest star a moving beauty mark.
The transit is happening during a six-hour, 40-minute span starting after 10pm in the UK.
The show can be seen in its entirety from the western Pacific, eastern Asia and eastern Australia. Other parts of the globe will catch portions of the transit.
Sunny spots in Hawaii, Alaska, eastern Australia and eastern Asia will get the whole show while viewers in the UK could part of it around sunrise.
If clouds spoil your view or if you are shut out, there is always the Internet. Nasa plans a live webcast from Mauna Kea, Hawaii. Slooh.com and the Exploratorium in San Francisco are among others that will the sky show broadcast online.