History of Moon Investigation

Around 400BC, Aristotle deduced that the Earth was round from the shape of the Eath's shadow on the Moon during a lunar eclipse.

About 200BC, Hipparcos carried out a calculation of the dimensions of the Earth-Moon system.

In March 1610, Galileo produced his Sidereus Nuncius detailing, among others, his Moon observations of 1609 (30. November 1609 is believed to be first observation of the Moon by Galileo). This book had enormous influence and obviously attracted enormous opposition. Galileo thought he was looking at oceans and called them maria. They actually contain basalt.

Since I am based in Britain, I cannot help but be aware of rival claims for the first telescope observations of the Moon. Thomas Harriot observed the Moon on 26 July 1609. On viewing Galileo's book, he attempted his own drawings although these seem to have had little influence (this is an assumption on my part because these drawings were only rediscovered in 1965).

None of these early maps contained enough detail to be able to actually indulge in large-scale naming of features. Langrenus (Michael van Langren of Amsterdam) began a Moon map project with both this idea in mind (of being responsible for the naming) as well thinking of being able to solve the longitude problem. He did at first receive assistance from King Felipe IV of Spain, suffered setbacks nevertheless but produced his map by 1645 (see below).

Moon map by Langrenus

Work in a similar vein was also carried out by Pierre Gassendi, a professor of Mathematics in Paris. He seems to have abandoned this work in favor of Helvelius when he learnt of or saw some of his work.

From about 1637 onwards, the British astronomer Jeremiah Horrocks, announced to a friend that he was attacking the problem of the Moon's motion. He soon stated that to a first approximation, the orbit was an ellipse with the Earth at a focus. This was not just a straightforward statement of Kepler's law - he did actually calculate the orbital constants.

In the 1640s, Helvelius built himself an observatory in Danzig (present-day Gdansk). Coming from a wealthy family, he had the means to do so and ultimately he had a telescope about 40 meters long based n his rooftop observatory (telescopes tended to be long in general because of the poor quality of the object lens at the time. He commenced to study the Moon in earnest in the Autumn of 1643 and in 1647 produced his Selenographia which named 257 features, only four of which have remained.

At the time, his map incensed Langrenus, who appears also to have made suggestions of plagiarism - at the very least he was upset that Helvelius made no mention of his work despite Langrenus claiming that he had seen it.

Three rival theories of the Moon's motion appeared in short order.

The 'New Almagest' by Giovanni Riccioli appeared in 1651 (seemingly based largely on observations by his pupil, Grimaldi). This was a work which was originally perceived as an anti-Copernican tract in line with contemporary Jesuit aims. His names are largely those in use today - the decision by Cassini, the first director of Paris Observatory, to use the nomenclature was highly influentual in this respect.

D'Alembert Système de Monde, published in three volumes in 1754

Tobias Mayer in conjunction with James Bradley, Astronomer Royal, constructed the lunar tables for which his widow received 5000 pounds from the British parliament, giving Euler 300 pounds as an honorarium. A map of the Moon by Mayer appeared in 1775 which was more accurate than anything before.

1764 libration of the Moon (by Lagrange) and why same face always to Earth (used virtual work) 1773 secular motion of the Moon earliest introduction of the idea of a potential.

Hieronymus Schröter was the first person to map details like rilles. He produced his Selenographische Fragmente in 1791. He added about 70 new names and used the word 'crater' for the first time. Tragically, all his equipment (in Lilienthal) was destroyed by French armies in 1814.

Laplaces ideas on the secular acceleration of the moon are implicitly involved in Lagrange's results

Johann Heinrich Mädler

Julius Schmidt completed a map left unfinished by Wilhelm Lohrmann but it was out of the date by the time it appeared. He did however engage in many measurements of crater depths and mountain heights. H eproduced his own map in 1878 (20 years beforhand he had been appointed Director of Athens Observatory). In 186, he had stirred up great interest in thge Moon when he annouced that Linné in the Sea of Serenity had disappeared, which is not true, as it turned out.

Photography started to become important in recording the Moon. Lewis Rutherford and Fred Whipple are important names here, and some photos were shown at the Great Exhibition in 1851. It would be some years yet before photography could be used to map the Moon (but not too many).

George Darwin (1845 - 1912). A son of Charles Darwin. In 1883 he became Plumian professor of astronomy and experimental philosophy at Cambridge University. He studied tidal effects on the planets. In particular, using methods introduced by Laplace and Thomson, he discussed the effects of tidal action on the Sun-Earth-Moon system. One of his theories, namely that the Moon was pulled from a molten Earth early in its history by tidal action of the Sun, is now considered incorrect.

Darwin made a major study of the three-body problem in the case of the orbits of the Sun-Earth-Moon system. He also studied the stability of rotating fluids, again motivated by his interest in the Moon being formed in fluid form from a molten Earth. His conclusions that a pear shaped rotating mass is stable is today thought to be incorrect.

Despite the fact that we do not accept Darwin's conclusions today, he is important in being the first to apply mathematical techniques to study the evolution of the Sun-Earth-Moon system.

In 1873, Richard Proctor suggested that craters were caused by meteorites. Grove Karl Gilbert

In 1896, the first photographic atlas the Moon published by Lick Observatory.

In 1904, William Pickering (brother of Edward was Director) of Harvard Observatory produced an atlas of moon photographs. Between 1919 and 1924 he studied the crater Erastothenes and came to the conclusion that dark patches were in fact vegetation.

The opening of the Mount Wilson telescope in 1919 produced photographs of the Moon which established the superiority of this method.

The International Astronomical Union was formed in 1919 and the systemized the nmaing of lunar features.

H. Percy Wilkins produced the largest map of the Moon prior to the space age, about 7.5 meters in diameter. It took him 40 years.

Wallace J Eckert earned his PhD was from Yale in 1931 in astronomy. At that time Ernest Brown was a member of the astronomy department and Brown's work on the Moon was an important ingredient of Eckert's later work. Eckert had joined the Faculty at Columbia University in 1926 and later he became professor there. Eckert was an early user of IBM punch card equipment to reduce astronomical data and solve numerically planetary orbits. In 1937 Columbia University and IBM established the Thomas J Watson Astronomical Computing Bureau as a result of the collaboration with Eckert. In fact the work which led to this development was published by Eckert in Punched card methods in scientific computation (1940). In 1940 Eckert became director of the US Nautical Almanac Office and produced work vital to navigation during World War II. In this post he introduced machine methods to compute and print tables and he began publication of the Air Almanac in 1940. In 1945 Eckert became director of the Watson Scientific Computing Laboratory at Columbia University. As stated in [3]:- During the more than 20 years he was in charge of the laboratory, it was a major training center for scientific computation, where more than 1,000 astronomers, physicists, crystallographers, statisticians, and other scientists studied. Eckert directed the construction of a number of innovative computers. In 1949 the Selective Sequence Electronic Calculator (SSEC) was built. Later the Naval Ordnance Research Calculator (NORC) was built. Completed in 1954 it was for many years the most powerful computer in the world. Eckert applied computers, in particular the SSEC and NORC, to compute precise planetary positions and contribute to the theory of the orbit of the Moon. In particular he used the SSEC to compute the positions of Jupiter, Saturn, Uranus, Neptune and Pluto, publishing the results in 1951 in Coordinates of the five outer planets. The NORC was used by Eckert to work on the problem of the position of the Moon. Writing in 1954 Eckert explained the how Brown had calculated the Moon's position:- Since 1923 the work of E W Brown has constituted the basis for the published ephemerides of the moon. His monumental calculation, which occupied most of his lifetime, consists of two distinct steps. The first is the development of the theory or the solution of the differential equations of motion expressing the coordinates of the moon as explicit functions of time. Secondly, in order to reduce the necessary labor involved in computing the coordinates of the moon for any given date from these formulae, Brown computed from his theory a set of Tables which, including the necessary explanations, comprise over 650 large quarto pages. ... In order to bring the Tables within even their present length, various parts of the basic equations were curtailed whenever permissible in the light of observational requirements (as then visualised). However by the 1950s it was realised that the Tables were not accurate enough. Eckert therefore decided not to recompute new tables but to compute the ephemeris directly from Brown's equations. The task was immense for, see [3]:- ... Brown's formulae involved some 1,650 trigonometric terms, many of them with variable coefficients. The accuracy of Eckert's calculations of the Moon's orbit was so good that in 1965 he was able to correctly show that there was a concentration of mass near the lunar surface. In 1967 he produced theoretical work which improved on Brown's theory of the Moon. Eckert's work is summed up in [3]:- Eckert retired in 1967 from IBM and in 1970 from his professorship at Columbia, greatly honored by his fellow astronomers but because of his modest nature little known to the public. Hardly any other astronomer of his generation influenced our science more profoundly.

kuiper put forward theidea that the moon had been differentiated (in 1959, an atlas he had compiled was published). Harold Urey put forward the idea that it was assembled from cold objects.

Thomas Gold of Cambridge University championed the idea that any spacecraft would sink deeply into the dust on the Moon.

Note Brans - Dicke Calder 141 Einsteinís Universe