06-08-2004, 08:37 PM
astronomical object passes in front of a larger one. During a transit of Venus, the planet Venus passes directly between the Earth and the Sun.
From the Earth, observers watching a transit of Venus see a circular silhouette creeping across the face of the Sun.
Why are Transits of Venus so rare?
Venus orbits the Sun just over three times in the time it takes the Earth to orbit twice. This means that Venus passes between the Earth and the Sun roughly once every nineteen months.
However, there are at most two transits of Venus every century. This is because Venus and the Earth orbit the Sun at a slight angle to each other. When we watch from the Earth, Venus usually appears to pass above or below the Sun, rather than crossing it.
See how the Earth and Venus move - This link will take you outside the BBC
Where can I see the transit from?
Observers in most of Europe, Africa and Asia will be able to see the transit in its entirety. Observers in Australasia and the Eastern Americas will be able to see part of the transit.
Check NASA's map of where you can see the transit
How can I watch the transit safely?
As always, the golden rule is NEVER LOOK DIRECTLY AT THE SUN, either with the naked eye, or through a telescope or binoculars. Doing so can lead to permanent blindness.
The safest way to view the event is by projecting an image of the Sun onto a sheet of white paper or cardboard.
How to view the transit safely - Advice from the University of Central Lancashire
You can also watch the Transit live on BBC One
Which other planets undergo transits?
From the Earth, observers watching a transit of Venus see a circular silhouette creeping across the face of the Sun.
Why are Transits of Venus so rare?
Venus orbits the Sun just over three times in the time it takes the Earth to orbit twice. This means that Venus passes between the Earth and the Sun roughly once every nineteen months.
However, there are at most two transits of Venus every century. This is because Venus and the Earth orbit the Sun at a slight angle to each other. When we watch from the Earth, Venus usually appears to pass above or below the Sun, rather than crossing it.
See how the Earth and Venus move - This link will take you outside the BBC
Where can I see the transit from?
Observers in most of Europe, Africa and Asia will be able to see the transit in its entirety. Observers in Australasia and the Eastern Americas will be able to see part of the transit.
Check NASA's map of where you can see the transit
How can I watch the transit safely?
As always, the golden rule is NEVER LOOK DIRECTLY AT THE SUN, either with the naked eye, or through a telescope or binoculars. Doing so can lead to permanent blindness.
The safest way to view the event is by projecting an image of the Sun onto a sheet of white paper or cardboard.
How to view the transit safely - Advice from the University of Central Lancashire
You can also watch the Transit live on BBC One
Which other planets undergo transits?