Thursday, 11 September 2008
The Moon Crescent in the Tropics, Sky Watch
All over the world people have seen the moon in various shapes as a full moon, as a crescent moon. The difference is that in Australia, and other countries in the tropical zone, the crescent is lying like a ship or like a dome over the country, while we in the more northerly or southerly regions see the crescent standing vertically. See the bottom most picture and compare it to the photos we took in Australia. We were amazed to see the horizontal crescent.
How was the moon formed? There are many theories.
The prevailing hypothesis today is that the Earth–Moon system was formed as a result of a giant impact. A Mars-sized body (labelled "Theia") is believed to have hit the proto-Earth, blasting sufficient material into orbit around the proto-Earth to form the Moon through accretion. As accretion is the process by which all planetary bodies are believed to have formed, giant impacts are thought to have affected most if not all planets. Computer simulations modelling a giant impact are consistent with measurements of the angular momentum of the Earth–Moon system, as well as the small size of the lunar core. Unresolved questions regarding this theory concern the determination of the relative sizes of the proto-Earth and Theia and of how much material from these two bodies formed the Moon.
Thanks to the Sky Watch team. For more photos click on the Sky Watch picture