ASE logo The Astronomical Society of Edinburgh

Journal

No 47 - December 2004

Observing Is Not Believing

Transient Lunar Phenomena (TLP) comprising glows and hazes on the Moon's surface have been reported by observers for a long time. There is an association with certain craters and maria but the causes of TLP is still a matter for debate. A gas emission was detected on November 3 1958 by Dr N.A. Kozyrev observing the central peak of the crater Alphonsus with the great refractor at Pulkova. NASA has reported the detection of tenuous emissions of gas by space vehicles, particularly radon, near the crater Aristarchus and around the peripheries of the circular maria.

Aristarchus

For a number of years I have observed the Moon on many occasions with my 152 and 216 mm reflectors at Newton Mearns, and my 63 mm reflector and refractor at Edinburgh. Even when TLP alerts were received I have never detected one at any time. There have been several occasions, however, when I have seen a reddish colour adjacent to Aristarchus. As will be noted on the accompanying drawing there is dark maria material to the left (inverted image) of Aristarchus and bright material on the slopes adjacent to the crater wall. On occasion the slopes have appeared with a reddish tinge but I am convinced that this is an optical effect. It could be generated by the contrast between the dark and bright surface combined with atmospheric movement.

As an illustration as to how the eye may be deceived I noticed a very interesting thing at a recent meeting of the Society. I was sitting in the dark near the entrance door to the lecture theatre, the President was speaking beside the overhead projector and at the time was wearing an anorak with black and white panels. On changing overlays the speaker moved in and out of the bright zone of light escaping from the projector. During these movements I experienced a distinct flash of red light apparently on the white portions of the anorak. This would appear to be another case where light contrasts and movement have combined to produce an apparition of spurious colour.

(Ron and I discussed this and concluded that the phenomenon was not a result of a residual spectrum thrown out by the Fresnel lens of the overhead projector. It seems to occur in the momentary flash from black to white. Spurious red images have been reported in similar cases, see M. Minnaert, "The Nature of Light and Colour in the Open Air", Dover 1954 ch. VIII ­ Editor.)

Ron Livesey


Contents

Cover page

From the President

Observing Is Not Believing

Eclipsing Binary Star - RZ Cassiopeiae

The BAA Honours our former Vice-President

The Astronomer's Drinking Song

About the ASE Journal


This journal as a single web page

This journal as PDF file (836 kByte)


Valid XHTML 1.0 Strict Valid CSS!