[extropy-chat] Frozen water ice found by ESA Mars Express on Mars.

[Rik van Riel]

On Sat, 30 Jul 2005, Bret Kulakovich wrote:

> Earth's surface is ~1 kw/m^2, which is true, but on Mars it is less than 
> 600w/m^2 = ~60%, i.e. substantially less.

The difference between a sunny day and a lightly overcast day.

> At Jupiter we're down to ~50 w/m^2, Saturn ~15.

I wonder how that compares with moonlight.
Google brings me to this Wikipedia article:

	http://en.wikipedia.org/wiki/Lux

Sunlight:       32000 to 100000 lux
TV studio:       1000 lux
bright office:    400 lux
sunset/sunrise:   400 lux
moonlight:          1 lux

Now, according to the mail uptread, sunlight on Mars is around
60% as strong as that on Earth, Jupiter has 5% and Saturn 1.5%.
Using the weakest luminosity for sunlight on Earth, that gives:

Mars:           20000 lux
Jupiter:         1600 lux
Saturn:           480 lux

Of course, this is the strength of sunlight in these orbits.
The luminosity of objects on which sunlight reflects will be
significantly less.

Still, sunlight on the good areas of Mars shouldn't be any
worse than sunlight during spring and autumn in northern
regions on Earth - eg. Scandinavia.  Enough to grow things
in a greenhouse...

-- 
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." - Brian W. Kernighan