![]() ![]() The period from one New Moon to the next, called a synodic month or lunation, is 29.5 days. Its angular size thus varies from 29.4 up to 33.5 arc seconds and when at its furthest distance cannot fully cover the Sun’s disk during a solar eclipse so that an annulus of the Sun surrounds the dark lunar disc and one sees what is called an ‘annular eclipse’. The Moon orbits the Earth in an elliptical path so that its distance varies from 356,400 km at perigee to 406,700 km at apogee. It plots an excellent chart of the visible part of the lunar surface for any chosen date and time and will provide detailed information about any feature that is selected as shown in the figure below.Ī comparison of its chart and the author’s image at the same lunar phase is shown in the image below. There is one piece of free software that every lunar observer should have and that is the ‘The Virtual Moon Atlas’. ‘Phillips Night Sky Atlas’ by Robin Scagell is a superb book for beginners and it has an excellent chapter on the Moon containing four, beautifully drawn, lunar quadrant charts. This can sometimes be found second hand but is now quite rare. It includes very detailed maps drawn by Wilkins. This is the highest resolution lunar chart available and can be bought second hand for ~£64.Ī classic Book with excellent descriptions of lunar craters and features written by Patrick Moore is ‘The Moon’ by Wilkins and Moore. The, large scale, ‘Times Atlas of the Moon’ is based on the Lunar Surveyor images and charted by the US Air Force. This is ~£25 from Amazon but may be found for less. (New copies are VERY expensive!) A superb photographic atlas is the ‘21 st Century Atlas of the Moon’ by Wood and Collins. It is well worth seeking out a second hand copy. In this short series I will first point out some of the aids that can help when planning lunar observations and then describe some of its most interesting features.Ī classic, hand drawn, lunar atlas is the ‘Atlas of the Moon’ by Antonin Rükl. This allows one to progressively dim the view of the Moon to the desired level whilst, at the same time, increasing contrast, reducing glare and so increasing the amount of detail that can be studied. Each filter set consists of two polarizing filters, one which can be rotated in its cell to adjust the brightness down from ~40% to ~2%. Even better, a polarising filter can be obtained from about £28 for use with a 1.25 inch eyepiece or £40 for use with a 2 inch eyepiece. Any telescope can be used and a “Moon filter” used to reduce its brightness so that it does not dazzle the eye. An article in the author’s Astronomy Digest – Ī great thing about observing the Moon is that it is easy to find and very bright (perhaps too bright) so that it can be one of the best objects for a beginner to study.
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