July 7, 2004

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Transient TLP


Image Credit: M. Cicognani, R. Lena

Transient TLP

Transient Lunar Phenomena (TLP) were the 20th century equivalent of the 19th century quest for change on the Moon. From Galileo to Herschel to Schroeter to the 1835 Moon Hoax to Pickering and his lunar insects, people wanted to believe that the Moon was inhabited. But as Beer and Madler conclusively showed in 1837, the Moon lacks water and air, and thus probably creatures. But hardline exobiologists of the 1800s thought that if changes in the lunar landscape could be detected than the phantom of life could be resurrected. In the 1970s Barbara Middlehurst and others compiled a catalog of all known changes reported on the Moon. These were historical accounts of flashes, clouds and obscurations, and they were simply accepted as true or false based on each person's philosophy about the likelihood of life off Earth. Recently, Raffaello Lena and Anthony Cook, in a joint British Astronomical Association and Geological Lunar Research Group project, reported an investigation of some of these claims by repeating the observations under virtually identical conditions of lighting and librations. This picture of sunrise on Alphonsus, taken by M. Cicognani on Aug 26, 2001 as part of the study, closely mimics the 1958 report of "a diffuse cloud over the central mountain, like a plume, very large compared with the central peak." Cicognani's image shows that the plume-like view reoccurs at exactly the same observing conditions, greatly reducing the possibility that the 1858 observation was a cloud. So it actually was a TLP - a Transient Lunar Phenomena - but the transitory activity was of lighting that illuminates part of Alphonsus' central spine! There was no physical change on the Moon. Bravo Raf and Tony!

Chuck Wood

Technical Details:
Left image by M. Cicognani, Aug 26, 2001 at 20:05 UTC using a 42 cm Cassegrain and a ccd camera. Right image by K.C. Pau, Oct 17, 2003 using a 10" Newtonian and a webcam.

Related Links:
Chronological Catalog of reported Lunar Events, Barbara Middlehurst and others, NASA Tec. Rpt. R-277 (1968).
Emergence of Low Relief Terrain from Shadow: An Explanation of some TL, R. Lena and A. Cook. J. Br. Astron. Assoc. 114, 3 (2004).

Yesterday's LPOD: A Long Graben

Tomorrow's LPOD: Magic on the Mare

Author & Editor:
Charles A. Wood



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