On Thursday, 21 November 2019 17:36:51 UTC, Dave Liquorice wrote:
On Thu, 21 Nov 2019 08:37:27 -0800 (PST), whisky-dave wrote:

And it's not just the light levels, but the colour temperature and
density of a source that can make a big difference as well (LED /
laser V an incandescent filament). You get bright lights at a
football
match for example but they aren't painful to look at.

Are they that bright though ?

These days at many Premier League stadiums each luminaire is about 2
kW LED and there are around 100 of 'em. They are no longer up
stantions in each corner but encircle the pitch mounted above/blew
the stand rooves. The light level, evenness and shadows (the playing
area is almost shadow free) are very tightly specified. Premier
League and Champions League have slightly different specs both can be
found on the 'net.

My local football team is Leyton Orient which might explain why I've not noticed.


Aslo mots can;t tell the colour of a star from just veiwing with the
naked eye. but they aren't all white. I can just make out that Mars has
a sort of orange colour.

Mostly down to the light level from the point source of a star not
being high enough for the cones to work. You can tell the colour of
the really bright stars.

Difficult in London unless you're in a dark place for a while.

Mars isn't a star. B-) and looks like a
red/orange dot to me, Jupiter is a definate disc.

I k ow but even the clever greeks called them wandering stars, and stars are brighter in reality but so far away and such a small 'footprint' that we can't easily tell the colour, which was my point.


--
Cheers
Dave.