The Orionids radiate from a point near the upraised Club of the constellation Orion the Hunter. The bright star near the radiant point is ruddy, somber Betelgeuse. You might catch an Orionid meteor any time between about October 2 to November 7. In 2021, the peak morning is October 21, but, around then, the full or nearly full Hunter’s Moon will be shining brightly.
When a meteor enters the earth’s atmosphere, friction between the particle and the increasingly dense air causes meteor particle to boil off. The particle collides with the air molecules forming trails of positive ions and free electrons used to reflect the radio waves. The reflecting process is primarily due to the effect of the electrons, since the positive ions are too massive to vibrate under the influence of an electric field.
The electron density of the ionized trail is commonly assumed to be Gaussian in the radial direction and the ionization may or may not be uniform in the axial direction. The length of the ionization region of a trial is approximately 20-40 Km from start to finish. It was found that useful ionized trails occur in an altitude of about 80 to 120 Km above the earth’s surface.
Trails with useful electron densities for reflecting radio signals were found to be plentiful enough to provide communication in the lower portion of (VHF) bond ranging from 30 to 100 MHz over a range of roughly 2000 Km. The minimum range limitation was found to be 400 Km. Ionized trails were found to have a lifetime of only a few tenths of a second, creating the need for rapid exchange of communication. The transmission rate had to be very fast (a burst of data) to take advantage of ionized trail. Hence the term “meteor burst” was coined.
Mike Terry to WOR iog (2021-10-20)