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THE CREATION OF THE
SOLAR SYSTEM MODEL
by David Thomas

THE BEGINNING OF OTFORD SOLAR SYSTEM
"I had read articles that tried to give an idea of the size of the universe, in particular the size of the Solar System but all descriptions were inadequate. I had also read books about previous civilisations where astronomical events were marked by monuments, for example Stonehenge and the pyramids.

When Otford Parish Council asked for ideas to celebrate the millenium, I felt we could mark it by an actual physical model of the Solar System with the planets in their correct position on millenium night and, at the same time, have a sense of its size.

Our sense of time comes from the motion of the planets, particularly the earth round the sun. In addition we could, in line with previous traditions, mark a particular point in time but use current astronomical knowledge."

CHOOSING THE SIZE
"We had to make the model big enough for the smallest planet, Pluto, to be seen by the naked eye and small enough to fit into the parish boundaries. This meant that Pluto had to be at least 0.5mm across, which is close to the limit of normal sight.

Since Pluto is about five billion kilometres away from the Sun, the scale for the model had to be about 1:5,000,000,000 - one to five billion - to allow it to fit within the 1 km radius parish boundaries."

CHOOSING THE POSITION
"We had to site the model so that all the planets could be visited by the public at any time. The planets form a giant 'clock face' with nine planet pillars as nine hands set for a particular 'hour'. The tips of the hands had to be at places with easy access.

Once we decided on the position of the Sun pillar all the rest had to follow. After many trials, errors and last minute setbacks, the present position enabled all the planets to be placed, on or close to, their true positions with the inner planets on the parish recreation ground and the outlying planets beside public footpaths."