I only recently caught up with David A Seargent's book, "Weird Astronomy: Tales of Unusual, Bizarre and Other Hard to Explain Observations," published in 2011 by Springer, New York. ISBN 978-1-4419-6423-6. As I usually do when I read any book, I check the index (if there is one) for any reference to UAP. Interestingly, for a book on astronomy, I found the following:
1. The O'Neill 'Moonbridge.'
In 1953, the science editor of the New York Tribune reported seeing, a lunar feature, which he thought was a several kilometre long 'natural rock bridge.' It appears the correct interpretation of the feature, is that it is an 'illusion' due to light and shadow. Seargent writes, "There is no Moonbridge. Unfortunately though, that has not stopped the subject from having become absorbed into UFO literature of the more crackpot variety...sensationalist writers tried to turn the bridge into proof of intelligent life..." (p.22.) For more on this, click here.
2. Nebulous meteors.
One rare, but accepted, category of meteors, is a 'nebulous' one. They are second to third magnitude in brightness, and "...show as a fuzzy ball about half the size of the full Moon." (p.148.) They move across the sky, and last, about the same as an ordinary meteor. "Presumably these strange meteors are caused by extremely friable objects that dissolve into clouds of smoke-like particles upon entering Earth's atmosphere." (p.149.)
Seargent ponders the question asked by West Australian Jeff Wood, "...what a nebulous fireball would really look like." If there were such a thing . Would it be reported as a UAP? "Wood thinks so and suggests that meteor observers should pay attention to those UFO reports involving cigar-shaped objects cruising across the night sky." (p.150.) For more on unusual meteors of all kinds, click here.
In 1799 polymath, Alexander Von Humboldt, noticed "...that some of the stars appeared to be performing oscillatory movements that he called sternschwanken . Later, in 1887 the term became autokinesis." It is believed to be due to the brain incorrectly interpreting either eye movements, or correcting movement of muscle fatigued eyes.
Whatever the cause, people report that lights, e.g. stars, jump around when in fact they are stationary. Seargent writes: "The apparent movement of a star or planet as seen by an observer on the ground can be startling and may even trigger a UFO report..." (p.197.) For an example of autokinesis and UAP click here.
4. Daytime observing.
Naked eye observers can, beside the Sun and Moon, see up to two planets and two stars in the day time sky. The planets Venus and Jupiter, and stars Sirius and Canopus.
Seargent cites the instance of "...a major UFO scare...in a regional city in New South Wales" (p.277), which was eventually shown to have been the planet Venus.
I found this a fascinating read, with much interesting astronomical information. Autokinesis features in numerous raw UAP reports which I have looked into over the years. If you haven't yet read this book, I would strongly recommend that you do.