Lecture Notes:

• MOON
  Torn away by an immense collision during the Hadean era, the moon is the earths child born in fiery fury. The chemical composition of the moon is identical to that of the earths crust, and furthermore it has no nickel iron core. Features that are prominent in a small telescope are Mare Imbrium Mare Serenetatis, Mare Crisium, and the craters of Tycho, Copernicus, Eratosthernes, Archimedes, and Plato. Its oldest surface is that of the heavily cratered highlands, composed of low density rock which floated to the surface when the moon was still liquid abound 4.4 billion years ago. The moon has not forgotten its origins and synchronously rotates around the earth, with a sidereal period of 29.5 days and a synodic synodic period of 27.3 days.

• MERCURY
  A sun scorched world Mercury bears the mark of the proxmity of the sun in the darkness of its rocks as measured by its low albedo of .11. It lies .39AU, 58 million km, from the sun and in its highly elliptical orbit varies from 46 million km at perihelion to 70 million km at aphelion. Its perihelion advances by 574"/century of which 531"/century can be explained by Newtonian gravitational attraction of planets. But the remaining 43"/century was not consistent with Newtonian gravity and for over a century indicated that Newton was wrong. At first, an attempt to save Newtonian gravity from the trash heap was attempted by postulating the presence of an nobserved inner planet Vulcan, the gravity of which could account for the unexplained 43"/centurey. Eclipse after eclipse, Vulcan was pursued but was never found. By the end of the 1900s sufficiently careful eclipse measurements had been made to eliminate any planet, large enough to cause the perturbation of Mercurys orbit.

  The solution to this puzzle was supplied by Einstein in 1915 when he showed that such movement of its orbit is exactly predicted by curved space-time. This was the first of a series of tests applied to Newton and Einstein, in which Einstein always emerged the victor.

  Mercury rotates with a period of 58.65 days in a 3:2 resonance with its 88 day period of revolution. The planet rotates three times for every revolution, such that at every perihelion passage its equatorial bulge is in line with the sun.