In message ,
writes
Hi All -

I was showing Mars to some friends, as I suppose a lot of us are lately(!)
and a question came up that I couldn't eloquently explain -

Why does Mars, or anyplanet, appear as "black and white" through a pretty
good telescope, while all the photos are in glorious color?

My weak explanation was that I "couldn't afford a color telescope," then I
tried to remember the rods and cones in the eye and all that. But I know
there is a better and shorter way to explain this...

I've never seen Mars as anything but pale orange with faint grey
markings - I suspect that anyone who sees green markings is getting a
contrast effect with the orange. But Mars is definitely bright enough
to stimulate the rods in the eye (the colour sensors, if I guessed
wrong)
Similarly Jupiter appears yellow and brown and occasionally red (the
"Great Red Spot" is currently quite pale, AFAIK), but it isn't as bright
as the processed pictures you will see. That's the main problem - a lot
of pictures are "enhanced".
Even Saturn appears yellow.
A very few deep-sky objects show colour, but normally they are too
faint. The colour is real, though, and if you see a picture of a bright
red nebula that's how it would appear if your eyes were sensitive
enough. Hubble telescope pictures often use green for the wavelength
that is really red, though.
Only the Moon and Venus are really colourless under clear skies (and I
suspect other people may argue this).

To keep it short, if you're seeing a black and white planet I'm puzzled!
It isn't really the "red planet", but it's much redder than most stars
or planets.
--
"Roads in space for rockets to travel....four-dimensional roads, curving with
relativity"
Mail to jsilverlight AT merseia.fsnet.co.uk is welcome.
Or visit Jonathan's Space Site http://www.merseia.fsnet.co.uk