* Astronomy

How? Who? Why? From Agatha Christie to Dan Brown, all the best thriller writers know the value of leaving these questions dangling until the last page. But at least we discover the answers in the end. If mankind endures ten million years we may never discover the who and why of the most tantalising enigma in the British landscape.
No, not Stonehenge. That jumbo-sized sundial may still retain an awesome aura of mystery, but its makers left dozens of clues as to its function. Im talking about the vast monument a few miles north Silbury Hill, the 500,000-tonne mound of chalk and turf that our Neolithic ancestors spent an estimated four million man-hours constructing, for reasons that have been totally obliterated by the march of millennia.
After 4,300 years, Silbury is in the news again. Last week experts from English Heritage, using pioneering tunnelling technology from the engineering company Skanska, reached its centre, 40 metres beneath the summit. Their primary purpose was not archaeology but preservation.

Read more