Re: Detection of Nighttime Lighting by ETs?

In sci.astro.amateur message <ce4d2695-1a25-4095-9004-2f1b6db71430@26g20
00hsk.googlegroups.com>, Wed, 16 Apr 2008 15:13:15, Martin Brown
<|||newspam|||@nezumi.demon.co.uk> posted:

I expect the precise 100/120 Hz frequency modulation would get their
attention if they were ever able to resolve us and to separate the
signal from the noise (which I very much doubt).

300/360 Hz more likely, since distribution is 3-phase. I imagine our
mains is coherent across Great Britain; but maybe not across the British
Isles. Do we cohere with mainland Europe? Is North America coherent?

A radian at 50 Hz is about 3 ms, and c is 1 ns/ft; about 50% slower in
wires, so a radian corresponds to about 2 megafeet of grid, which is but
a fraction of a continent.

If the distant observer is placed to only see our night-side, he will be
staring into the Sun; if not, he will see an appreciable fraction of the
illuminated part of Earth. The whole Earth reflects about 5E16 W.
Present world energy use is under 2E13 W, the vast majority of which is
not converted into light; most of the light is indoors or downwards, and
much of what gets loose is absorbed by cloud.

There seems little chance, then, of ETs with only sub-magical technology
observing our light from near their residences.

OTOH, for an ET entering our system, artificial lighting might well be
the first visible sign of something strange going on here.

--
(c) John Stockton, nr London, UK. ?@merlyn.demon.co.uk Turnpike v6.05 MIME.
Web <URL:http://www.merlyn.demon.co.uk/> - FAQqish topics, acronyms & links;
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