Transit of Venus: What happens?

When Venus passes directly between earth and the sun on Wednesday, the distant planet will be seen as a small dot gliding slowly across the face of the sun. Photo / File

Sky-watchers around the world will see the planet Venus glide across the sun's face on Wednesday - the last chance to witness such an event until 2117.

The rare event will be visible in New Zealand from 10.15am to 4.43pm but weather forecasters say thick cloud across the country is likely to affect viewing.