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Date: | Sat, 18 Apr 2015 22:14:32 -0400 |
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Thank you Martin. I really enjoyed that. I have heard some of this when I
took physics in college etc. but I have forgotten a lot and didn't learn
some of that. I appreciate the lesson.
Kent Plemmons, Clyde, NC KK4FFF
-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Martin G. McCormick
Sent: Friday, April 17, 2015 4:21 PM
To: [log in to unmask]
Subject: Re: The Colors of the Stars
You are welcome. Stars are like a noisy transmitter. The Sun sends
out RF that we can pick up on radio receivers here with almost no
difficulty. There is Sun noise all the way from HF to daylight. Daylight is
just Sun noise you can see.
Generally, the higher we go in frequency, the more Sun noise we
pickup.
There were people back in the 1700's who theorized that there were
energies that we could not see that behaved like light but that was just
weird speculation that had no real value until a fellow by the name of Sir
William Frederick Hershel who lived in England did an interesting experiment
in 1800.
He was an astronomer and musician who built telescopes and generally
contributed a lot to astronomy by cataloging stars.
He was originally trying to figure out how much heat different
colors of sunlight had so he used filters of varying colors and eventually a
prism to break sunlight in to a spectrum or rainbow of all its colors.
His test devices were thermometers whose bulbs had been blackened
with lamp black. He would hold a thermometer in a certain color of light and
see how much it went up compared with a control thermometer which was
sitting outside the spectrum.
His big discovery occurred when he found that he could move the
thermometer past the red end of the rainbow and it went up higher than any
other color even though one could not see any sort of light.
If you want to read more, do a Google search for discovery of
infrared. That was the first article that came up.
There is a quote I have read by somebody whose name escapes me that
says, "Let's be thankful for the things we have and also for other things we
don't have."
What I am getting at is what else we get from the cosmos and our
Sun.
That broad spectrum electromagnetic radiation we get from the Sun
and other stars includes everything from ultraviolet through X-rays. We do
get some of the ultraviolet which is how we get sunburn and skin cancer but
things could be a whole lot worse.
Our atmosphere blocks the X-rays and some of the ultraviolet which
is why people are concerned about the ozone hole. The ozone layer way up
there near the outer edge of our atmosphere is sort of like a big Sun glass
lens that shields us fromX-rays and other cosmic rays that would positively
cook our geese very nicely if we ever were directly exposed.
When ten meters is alive with F2 propagation in Winter, we now know
that the Earth got blasted with X-rays from the Sun.
X-rays cause the ion density to increase in the F2 and other layers and make
DX on ten and six meters possible. If you were an astronaut doing a space
walk, however, you would want to go inside and maybe even come back to Earth
if it got bad enough.
The Solar Flux readings we get from WWV are Sun noise at
10.8 GHZ. If you hear them talk of an X-ray event, that is X-ray flux and we
can hope for ten and 6 to pop wide open.
Before I stop, here, I must remind anyone who is interested that
Sporadic E can be very spectacular on ten and six meters but that seems to
be triggered by some other mechanism that is not fully understood. It's not
X-ray flux and it can hit at night as easily as it does during the day.
Martin
Phil Scovell writes:
> Martin,
>
> Thanks for those details. Makes sense now that you put it that way.
> Thanks
> for sharing those details.
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