Celebrating a landmark experiment In 1919, British scientist Arthur Eddington embarked on an historic expedition to the island of Principe, off the west African coast, to observe a total solar eclipse.
Stars in the Hyades cluster were behind the Sun during the eclipse, and appeared to shift from their true positions. This discovery provided the first experimental confirmation for Albert Einstein's theory of general relativity.
On 29 May, the island of Principe marked the 90th anniversary of the experiment, described by many as one of the most important scientific achievements of the 20th Century.
Astronomer Richard Massey, from the Royal Observatory Edinburgh, has been in Principe with colleagues and is writing a diary for BBC News.
http://news.bbc.co.uk/2/hi/science/nature/8061449.stm![](http://newsimg.bbc.co.uk/media/images/45838000/gif/_45838055_gravitational_inf466x290.gif)
• Gravitational lensing occurs when the light from a distant object is bent around a massive object in between it and the observer.
• The massive body distorts the spacetime (represented as the yellow grid) making the distant object look distorted