Re: The sun's path and geography in Fantasy.

In article <4969fe98.347893584@xxxxxxxxxxxxxxxxxx>, Jonathan L
Cunningham <spam@xxxxxxxxxxxxxxxxxxxx> wrote:

On Fri, 09 Jan 2009 23:19:18 -0700, "David M. Palmer"
<dmpalmer@xxxxxxxxx> wrote:

See
http://www.asterism.org/tutorials/tut26-1.htm
for a plot of brightness vs. phase.

Interesting link. Thanks.

Shadows, I didn't think of shadows.


General Googleable terms are "opposition brightening" in astronomy and
"dry heiligenschein" for the more general effect. You can see this if
you are flying and look at the bright spot surrounding the shadow of
the plane (over some terrains). Or you can look at some of the Apollo
films from lunar orbit.

And of course nocturnal creatures will need less light than diurnal
folk, so the queen of the night, with her enchantingly large eyes will
be able to walk around in what we would consider darkness.

Yes. Our eyes are quite efficient photon detectors when they are dark
adapted. So I expect if Ric wanted to stand outside for twenty minutes
in the dark (!) he could manage on less light than a three day moon.

But after dark adapation, the only way to go is bigger eyes, I reckon.
(Putting reflectors on the back of your retina, like cats etc. helps a
bit, but it can't be more than a factor of 2 at best, can it?)

Googleable term "tapetum".

Other ways to go include:
Broader spectrum: which can range from not wasting the near infrared to
going all the way to heat sensing FLIR (e.g. pit vipers).
Longer exposure, which is helped by lower noise. Some fish have the
ability to change the temperature of their retinas, which corresponds
to faster or slower exposure: up in the light near the surface they
have faster response time due to warm eyes, while down in the inky
depths the lower temperatures mean that the optical pigments stay in
their photoactivated configuration for longer, giving a larger total
response to each photon.

"In the darkness she stared at me with her cold cold eyes."

And of course you can go non-optical with sonar etc.

--
David M. Palmer dmpalmer@xxxxxxxxx (formerly @clark.net, @ematic.com)
.

Relevant Pages

  • Re: a bout television
    ... I like to watch TV in the dark, though it does strain the eyes a bit. ... The only way a white screen can produce the illusion of black is if it is displayed in darkness. ... Remember that all the light seen by the entire audience, watching that large screen, first passed through a postage stamp sized frame of film, with a brightness rivaling the Sun. ...
    (sci.electronics.basics)
  • Re: The suns path and geography in Fantasy.
    ... day old moon correctly. ... Shadows, ... Our eyes are quite efficient photon detectors when they are dark ... in the dark he could manage on less light than a three day moon. ...
    (rec.arts.sf.composition)
  • Re: answer the question ardalan
    ... he is a lost soul.. ... > shadows of one another, which the fire throws on the opposite wall of the ... > presence of the sun himself, is he not likely to be pained and irritated? ... > When he approaches the light his eyes will be dazzled, ...
    (soc.culture.iranian)
  • Re: answer the question ardalan
    ... he is a lost soul.. ... and they see only their own shadows, or the shadows of one another, which the fire ... ascent, and held fast until he is forced into the presence of the sun himself, is he not likely ... When he approaches the light his eyes will be dazzled, ...
    (soc.culture.iranian)
  • Re: answer the question ardalan
    ... he is a lost soul.. ... How could they see anything but the shadows if they ... When he approaches the light his eyes will be dazzled, ... >>> night better than the sun or the light of the sun by day? ...
    (soc.culture.iranian)
Loading