Ordinary Meeting, 2002 February 23
A Biography of the Moon
Dr. Whitehouse opened by suggesting that no book could ever capture the Moon's full character, as it is surrounded by mystery and myth. Historically it has been praised, and given many names including the Greek "hecate" – power from afar. It has been associated with changeability, power, and even female fertility. Some believe that the religious significance of a return after three days has origins in the return of a new moon.
The speaker emphasised that lunar observations were recorded well before Galileo. In the 1500s, Leonardo produced many line drawings of the Moon, around half of which are still unaccounted for and may lie in the Vatican's vaults. Earlier still, in 1430 Van Eyck placed the Moon in the backdrop of his Crucifixion scene. This was revolutionary at the time, as previous artists had painted attempted to paint through God's eyes, removed from material things such as the Moon.
Prehistoric moon observations from circa 3500BC are recorded at the Knowth burial site in Ireland where the ceiling of a tomb is clearly decorated with stars and lunar crescents. Engravings on a large boulder resemble the moon, and are orientated precisely to match the Moon as it would be seen rising as its light shone into the tomb. In the 1940s, cave paintings were discovered in the Lascaux caves in France showing the constellation of Taurus with a bull, indicating this association to be prehistoric. But groups of 29 dots also commonly appear – possibly a lunar calendar. Squares mark the absence of the Moon. These paintings have been dated as early as 20,000BC.
Dr. Whitehouse then compared two Space Races – firstly that of the 17th century to map the Moon with the aid of Lipperhay's invention of the telescope – and secondly the more familiar race during the Cold War era. The first telescopic lunar map is believed to be that of the English physician William Gilbert from around 1600. This was closely followed by Thomas Harriot, a wealthy English polymath, who drew detailed scientific maps in 1609. The speaker commented on his disappointment that these maps, surely a great national treasure, lie in the storeroom of a stately house in Sussex. The names we now attribute to lunar features are credited to Ricioli – a Jesuit priest who mapped the Moon in 1651. Curiously, his job description at the Vatican was to attempt to bring astronomy down, and to prove Ptolemeic celestrial mechanics. However when he named the features on the Moon after celebrities he clustered people according to the nature of their contribution, and placed himself as a scientist rather than a religious figure, possibly a sign of where he felt his greatest contribution was.
The speaker then discussed the Space Race of the 1960s, focussing on the results. It was found that Moon samples were very similar to the rock found on Earth with the water removed. This is useful when attempting to ask where the Moon came from. The Darwinian theory of a droplet of Earth material being thrown off in its early formation, or the idea of the Moon being captured gravitationally are both implausible. The angular momentum of the Moon supports a theory that an impactor the size of Mars split the early "proto-Earth" into two pieces in an oblique collision. Were this the case, the speaker proposed that the impact would have split the Earth in 15 minutes, and accumulated into the Earth-Moon system in two weeks. Hence the Moon was almost certainly formed in under a year. All this is in good agreement with the findings of the 1970s.
Finally, the speaker put forward a case for establishing a manned Moon colony. Recent observations of the lunar poles by Lunar Prospector had indicated that in some regions where the Sun has not shone for 2-3 billion years cometary water could have accumulated. As well as being useful for human survival, this could also be used to make rocket fuel. Polar regions also offer mountaintops with sunlight 97% of the day, ideal for solar panels. Furthermore as these are close to very cold regions, effective heat engines could be established. Dr. Whitehouse urged that such a moonbase would increase public interest in Space, and could be achieved in as little as 2 years if resources were invested into it.
After much applause for the fascinating talk, the meeting broke for tea. After the break, the President commented on the superb attendance at the preceding Comet Section meeting, expressing his hope that more comet observation might result. He then invited Mr. Martin Mobberley to give Sky Notes.