AAQ Solar System Section

Lunar Observing Programme

The Astronomical Association Of Queensland lunar observing programme commenced in August 2001 with the aims of:

• increasing the quantity and diversity of observational activities being undertaken by members; and to

• introduce planetary geology concepts that will provide members with an improved understanding of how lunar features observed through an amateur telescope formed.

The observing programme consists of 20 features that are easily observed through a small telescope and are archetypal examples of their kind. The programme includes a variety of craters of different morphology, mare, mountains, fault scarps, wrinkle ridges and rilles (valleys).

The following table lists the name, feature type, location and sunrise time for the 20 features to be targeted by the observing programme. The features are listed in the order they have or will be presented at meetings. Feature location is given using International Astronomical Union (IAU) convention with north located above Mare Imbrium and east beyond Mare Crisium. Latitude is given in degrees north or south of the equator (passes through the southern boundary of Mare Tranquillitatis). Longitude is given in degrees east or west of the prime meridian (passes through Crater Ptolemaeus). The sunrise time is the approximate time measured in days from new moon when the morning terminator reaches the feature. The actual time will vary from lunation to lunation due to libration. Add 15 days to the indicated times to estimate when sunset occurs, that is when the evening terminator passes the feature.

The locations of the above features are also illustrated below on Figure 1.

Figure 1: Location Of Lunar Observing Programme Targeted Features (Note: The numbers refer to the feature numbers in the above table. The numbers are positioned immediately to the left of the feature.) Photograph courtesy of Russell Croman, © 2005 Russell Croman, www.rc-astro.com

The best time to observe a feature is when the terminator is located on or near the feature. That is around sunrise or sunset as the Sun is low to the lunar horizon and consequently long shadows are cast thereby showing topographic relief to best advantage. It is also worthwhile observing a feature at both sunset and sunrise as the view can be markedly different at these times. In other words plan your observing sessions around the position of the terminator to gain maximum benefit from the lunar observing programme. The exception, to viewing a feature when it is placed near the terminator, is crater ejecta rays. The rays are best observed around full moon as the sunlight strikes the lunar surface at a high angle eliminating shadows and enhancing albedo differences between the rays and the surrounding terrain.

The following articles on the lunar observing programme features and related lunar geology topics are available:

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© 2006 Anthony Dutton, Astronomical Association of Queensland

Astronomical Association of Queensland 2006. www.aaq.org.au