Venus
The transit of Venus - where the planet Venus
passes directly between us and the Sun, took place on 8th June 2004.
Since this is a very rare event - the last one was in 1882, it is of great interest to astronomers. One reason
is that it was once the only means to measure the distance of the
Earth to the Sun, by timing how long it takes for Venus to transit
from one edge of the Sun to the other. Knowing the speed of rotation
of the Earth, this time is converted into a distance along one side
of an enormous triangle. The angle between one edge of the Sun and
the other can also be visually measured. So, we all know from school maths!, that having a side and an angle of a right angled triangle
means we can find the other lengths, one of them being the distance
to the Sun. This happens to be roughly 149, 600, 000 Km. QED!. There
will be another one on June 6th 2012, but after that, the next will
be in 121 years in 2117. So don't miss the one due in London
Olympics year.
The pictures below show the result of observing the transit by
projecting an image of the Sun onto white card through a pair of
binoculars, and how this was done with the help of my able assistant!
N.B. NEVER look at the sun directly through unprotected optical
devices.
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| Projected Image of Transit |
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| Projection Kit |
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| Astronomical Technician
Margaret |
