DARK AND DAYLIGHT METEORS
- Subject: DARK AND DAYLIGHT METEORS
Dark or black meteors are, in all probability, due to fatigue. When a meteoroid enters the atmosphere the friction it encounters causes an ionized train that glows because the ions are in a highly excited state. When they recombine with atomic nuclei any excess energy is emitted as light. So dark meteors are not apparently possible. As yet, no one has undertaken research to see when, in a meteor watch, dark meteors begin to appear. In all probability, they will occur towards the end of the watch when the observer is tired.
There are more believable reports of dark meteors crossing the face of the Moon. The most notable case concerned W.H.Steavenson in November 1920 who saw a dark meteor cross his telescope’s field of view while he was observing the lunar surface. He noted that the meteor was in perfect focus.
It would be very easy to dismiss Steavenson’s observation were it not for the fact that he was one of the most experienced observers of his day. He had received the Hannah Jackson Medal from the Royal Astronomical Society in 1928, was Editor of The Observatory between 1929-33, and President of the RAS from 1957-59. His view was that the object was a meteor but its contrast with the much brighter lunar surface made it appear dark in much the same way the sunspots appear dark against the more luminous sun.
Reports of both dark and light meteors occurring during the day are not unknown though it seems likely that such observations are due to flocks of birds, locust and seeds.
Copyright 1996 Philip M. Bagnall