What Time Is It, Centurion?

What did the Romans ever do for us? Well they may have built the most amazing sundial you'll ever see.

You would have to travel to Rome to see it, but the Pantheon (translated means 'All of the Gods') has possibly kept perfect time for the last 2,000 years.

Coincidence or Planned?

The large inscription on the front of the Pantheon reads in English 'Agrippa built this' and he was no cowboy-building Roman Emperor as it has stood there since it was completed in AD128. It was a temple originally and if you get the chance to go inside you will honestly believe it has stood for no more then a few hundred years - the design is that astonishing.

It consists of a cylindrical chamber topped by a perfectly formed domed roof which had to be constructed of light yet durable enough material to be supported by the structure below. The roof has a circular oculus at its top and this lets through a very dramatic shaft of sunlight - at the front it has a colonnaded courtyard which in turn is abutted by cobbled stones on which hundreds of camera-toting tourists stand plus a make-believe centurion. The small piazza is hedged by a ring of nice cafes and restaurants form which you can take in one of the most startling views of all antiquity - and then buy some leather gloves.

The Time Machine

In this week's New Scientist, a Professor from the University of Otago, Dunedin, Robert Hannah, contends that the Pantheon may be more than just a temple. He observes that during the six months of winter, the light of the noon sun traces a path across the inside of the domed roof, while in the six months of summer when the sun is higher in the sky, the shaft of light shines onto the lower walls and floor. At the two equinoxes in March and September, the sunlight coming in the through the oculus strikes the junction between the wall and roof above the Pantheon's northern doorway. A grill above the door allows a sliver of light through to the front courtyard which is the only moment it sees sunlight if its main doors are closed.

If you think that's just coincidence then frankly you must be barmy, it's argued, and you just have to agree that there was a reason for such an incredibly precise design. In Roman times, a hollowed-out hemisphere with a hole on top was often used as a sundial. This now conjures up images of these sundials being sold to visitors to the Pantheon in AD128 much as you buy plastic souvenirs in the shops there today - Monty Python may well have captured that one too in 'The Life of Brian'. It is remarkable to note that while the Pantheon's dome is quite flat on the outside it is a perfect hemisphere on the inside and Robert Hannah believes that telling time was the reason.

The Gods Will Be Pleased

In a way you would expect such a grand design to have special significance to the Gods it was designed for even if it has been hijacked by Christianity inside nowadays. In Roman times, the connections with the Gods and stars was seen as a given and the dome of the Pantheon is certainly symbolic of the sky where it was believed the Gods resided. At equinox, when the sun is on the celestial equator, the line traced away from the earth's equator would be the perfect place for the Gods to be located and hence the temple's connection.

There is of course a minor flaw in the theory. There are no markings anywhere in the temple as you may find in a sundial to help tell the time. Then again, it may be one of those subtle precursors of a Rolex where telling the time was only a loose byproduct of a largely expensive aesthetic product.

Those Romans were clever devils, you know.