The almost seven-hour "transit" of Venus across the face of the sun was set to conclude in the early hours of Wednesday morning, not to reoccur until 2117.

People around much of the world - with much of South America, Western Africa and Portugal among the unlucky areas to miss out - were able to see a small black circle moving across the face of the sun. Venus appears to be about one fortieth the size of the sun itself.

Venus, the second planet from the sun in our solar system, "crosses" the sun - from our vantage point - roughly twice a century, in pairs about eight years apart. The last transit took place in 2004; the next is over 100 years away.

People in the southern hemisphere would see Venus moving across the lower half of the sun, while those in the northern hemisphere would perceive it to cross the top half.

Various web sites and smartphone Apps sought to stream the passage live, while scientists and health experts repeatedly issued their standard appeal to people not to look directly at the sun, something which can seriously damage your eyes.

msh/av (AP, dpa)