Hi,

This was posted by Hilmar in the Chatter forum, and I thought
any lurkers would find this as interesting as I.


****** From Hilmar ******
I was just reading an article in "Das Himmelsjahr" (astronomical anuary) about planet Vulcan. Just as Neptune (and later Pluto) was found by irregularities in the orbits of Uranus, it was believed that formerly unexplained irregularities in Mercury's orbit (the Perihelion, point of closes approach to the sun, advanced 43 seconds more, each year, than expected), were caused by an inner planet. This planet was called "Vulcan".

The irregularities were later explained by the General Theory of Relativity: space close to the sun is not exactly "flat".


Another interesting point is the fact that light rays curve towards large masses. This can be observed by stars behind the sun (in the case of a solar eclipse), but a star, or an entire galaxy, can act as lenses to focus the light of objects behind them. Several othewise invisible objects have been detected that way - by irregularities in the light of objects behind them.

Hilmar.