"david" wrote:

Just reading the latest issue of Pop. Astronomy and on page 21, in an
article about the transit of Venus, it states that the event is rar, each
transit ctually occuring in pairs eperated by over a century.

Then it says, and I quote,

"Currently, transits of venuse follow in the order 121.5, 8, 105.5, 8 years
and they will continue in this sequence for another 1000 years".

Now what the heck does that mean?


David

Did you spot that 8+105.5+8=121.5? The pattern isn't quite as odd as
it looks at first sight.

While the earth goes round 121.5 times, Venus goes round 197.5 times +
4 hours - so it they start together they'll not only be together
again, they'll be at exactly the same point in their orbits 121.5
years later. The 4 hour discrepancy means the pattern of transits
won't last for ever but it'll see us out and another 1000 years.

--
Martin Frey
http://www.hadastro.org.uk
N 51 02 E 0 47