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47317 |
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Date: March 23, 2023 at 19:29:27
From: pamela, [DNS_Address]
Subject: a report from spaceweather.com re last months, radio burst |
URL: https://spaceweather.com |
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A SOLAR RADIO BURST AT NIGHT: Something rare and
strange happened last month. On Feb. 23rd, growing
sunspot AR3234 produced an M-class solar flare. It was
nearly midnight in Florida when the explosion occurred,
so you'd expect no one there to notice. On the
contrary, in the community of High Springs, FL, amateur
radio astronomer Dave Typinski recorded a strong
shortwave radio burst.
"You CAN see the sun at midnight in Florida...
sometimes," says Typinski. This is what his instruments
recorded while the flare was underway:
see photos at link
A double wave of static washed over Florida, filling
the radio spectrum with noise at all frequencies below
25 MHz. "The Sun was 69° below the horizon when this
happened," he marvels.
How is this possible? The entire body of our planet was
blocking the event from Typinski's antenna. It's called
"antipodal focusing." First postulated by Marconi more
than 100 years ago, antipodal focusing is a mode of
radio propagation in which a signal starts out on one
side of the planet, gets trapped between Earth's
surface and the ionosphere, and travels to the opposite
hemisphere. Waves converging at the antipode can create
a surprisingly strong signal.
Right: This diagram from a declassified US Gov.report
shows the basic geometry of antipodal focusing.
"This is the second or maybe third midnight solar radio
burst I've seen in ten years, but it's by far the
strongest," says Typinski. "The previous events
happened at the height of Solar Cycle 24. They're quite
rare."
Pause: Yes, solar flares can produce radio signals.
Typinski's midnight burst was a "Type V," caused by
streams of electrons shooting through the sun's
atmosphere in the aftermath of the flare. Plasma waves
rippling away from the streams emited intense bursts of
natural radio static. The burst was first observed in
broad daylight at the Learmonth Solar Observatory in
Australia, then it curved around Earth to reach
Typinski.
Above: An example of antipodal focusing of seismic
waves caused by the Chicxulub asteroid impact. The
geometry is the same as for radio waves. [more].
"This propagation mode was used during the Cold War,"
notes Typinski. "The U.S. would park a SIGINT ship in
the south Pacific to grab signals from the Eastern
Bloc. The Soviets probably did the same thing, parking
in the southern Indian ocean."
Turns out, this method of spying works for radio
astronomers, too. Would you like to record an event
like this? NASA's Radio JOVE program makes it easy.
Off-the-shelf radio telescope kits allow even novices
to monitor radio outbursts from the sun, which are
becoming more frequent as Solar Cycle 25 intensifies.
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Responses:
[47326] [47323] [47327] |
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47326 |
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Date: March 24, 2023 at 13:53:55
From: Eve, [DNS_Address]
Subject: Re: a report from spaceweather.com re last months, radio burst |
URL: https://spaceweather.com/archive.php?view=1&day=23&month=03&year=2023 |
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Helpful link that will take one to the visuals given in the article posted:
https://spaceweather.com/archive.php?view=1&day=23&month=03&year=2023
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Responses:
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47323 |
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Date: March 24, 2023 at 12:45:16
From: Earthstone, [DNS_Address]
Subject: Cool guide to Schumann resonances, magnetosphere etc |
URL: https://wildfreeorganic.com/schumann-resonance-complete-guide |
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Cool guide to Schumann resonances, magnetosphere etc
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Responses:
[47327] |
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47327 |
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Date: March 24, 2023 at 14:33:45
From: pamela, [DNS_Address]
Subject: Re: Cool guide to Schumann resonances, magnetosphere etc |
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Responses:
None |
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