http://spaceweather.com/index.php
This might be the first such event on this scale since 1958, according to Spaceweather, though there was at least one other event reported in 1976:
Here's the full-text Spaceweather linked to on the 1958 event. 2 theories are mentioned, but the 1977 article above seems to lean towards the theory of anomalies in Earth's ionosphere allowing the phenemenon, rather than the lunar reflexion theory.
http://www.typnet.net/AJ4CO/Library/...%201959%29.pdf
NIGHT-TIME SOLAR RADIO BURST: The M9-class solar flare of August 4th produced a burst of shortwave static so powerful that receivers on Earth picked it up after sunset....
This might be the first such event on this scale since 1958, according to Spaceweather, though there was at least one other event reported in 1976:
Nature 267, 412 (02 June 1977); doi:10.1038/267412a0
Night-time reception of solar radio events
N. D'ANGELO
Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242
RIIHMAA has reported night-time reception of a solar radio event1. The observation, in the frequency range 20.85?23.20 MHz, was made at Kiiminki (65?05′N, 25?54′E) on 30 March 1976 with the Sun (and Jupiter) well below the horizon. Night-time reception of solar bursts had also been reported by Smith et al. 2. Such night-time solar radio burst reception might be brought about by anomalous propagation associated with plasma waves in the lower ionospheric E layer. I briefly discuss this phenomenon here and point out the possible importance of large ionospheric electric fields.
Night-time reception of solar radio events
N. D'ANGELO
Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242
RIIHMAA has reported night-time reception of a solar radio event1. The observation, in the frequency range 20.85?23.20 MHz, was made at Kiiminki (65?05′N, 25?54′E) on 30 March 1976 with the Sun (and Jupiter) well below the horizon. Night-time reception of solar bursts had also been reported by Smith et al. 2. Such night-time solar radio burst reception might be brought about by anomalous propagation associated with plasma waves in the lower ionospheric E layer. I briefly discuss this phenomenon here and point out the possible importance of large ionospheric electric fields.
http://www.typnet.net/AJ4CO/Library/...%201959%29.pdf
Anomalous Night-Time Reception of a
Major Solar Radio Burst
By Prof. ALEX G. SMITH. T. D. CARR and
W. H. PERKINS
Reprinted from Nature, Vol. 183, pp. 597-598, Feb. 28, 1959
DURING the'early morning hours of March 8, 1958,
the planet Jupiter was under observation by a total
of five different receiving arrays at the University of
Florida Radio Observatory. Two of these arrays
operated at a frequency of 18 Mc./s., two at 22?2
Mc./s., and one at 27?6 Mc./s. Both pen recording
and aural monitoring of the signals by an observer
were employed, At 0235 U.T. an unusual event
began simultaneously on all five channels, consisting
of a single very intense burst of noise which slowly
rose to a maximum, and even more slowly declined
over a total period of about 2 m.in. During this
interval the observer was able to obtain an
excellent record of the polarization of the disturb?
ance with the 22?2 Mc./s. polarimeter, which was
kept in stand.by condition during all periods of
observation.
[snip]
Although no direct comparison can be made because of this large difference in frequency, the orders of magnitude do not seem entirely to exclude the possibility of a lunar reflexion. (We would welcome intensity data from this event from any station which happened to record it at a frequency nearer 18 Mc./s.). The other possibility is, of course, that the radiation penetrated the ionosphere through an anomalous 'thin' spot in the daylight hemisphere, and was then propagated around the Earth by the usual modes of transmission....
Major Solar Radio Burst
By Prof. ALEX G. SMITH. T. D. CARR and
W. H. PERKINS
Reprinted from Nature, Vol. 183, pp. 597-598, Feb. 28, 1959
DURING the'early morning hours of March 8, 1958,
the planet Jupiter was under observation by a total
of five different receiving arrays at the University of
Florida Radio Observatory. Two of these arrays
operated at a frequency of 18 Mc./s., two at 22?2
Mc./s., and one at 27?6 Mc./s. Both pen recording
and aural monitoring of the signals by an observer
were employed, At 0235 U.T. an unusual event
began simultaneously on all five channels, consisting
of a single very intense burst of noise which slowly
rose to a maximum, and even more slowly declined
over a total period of about 2 m.in. During this
interval the observer was able to obtain an
excellent record of the polarization of the disturb?
ance with the 22?2 Mc./s. polarimeter, which was
kept in stand.by condition during all periods of
observation.
[snip]
Although no direct comparison can be made because of this large difference in frequency, the orders of magnitude do not seem entirely to exclude the possibility of a lunar reflexion. (We would welcome intensity data from this event from any station which happened to record it at a frequency nearer 18 Mc./s.). The other possibility is, of course, that the radiation penetrated the ionosphere through an anomalous 'thin' spot in the daylight hemisphere, and was then propagated around the Earth by the usual modes of transmission....