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

[Bret Kulakovich]

Mars, at opposition is almost at perihelion - only an additional ~.4  
AU, but at its furthest is actually ~.65 AU. So opposition isn't the  
average.

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

We also have to consider the rate that light drops off as a distance  
from its source, and that the albedo of Mars is about half that of  
Earth's.


]3



On Jul 30, 2005, at 12:14 PM, Mike Lorrey wrote:

> --- Bret Kulakovich <bret at bonfireproductions.com> wrote:
>
>
>>
>> At the distance of Mars, there is substantially less light, Jupiter
>> and Saturn even less. The images we see are being "pushed" into our
>> range of brightness.
>>
>
> Mars, at opposition, is only about 40 million miles away, which is
> about 40% further from the Sun than Earth (at 93 million miles).
> Sunlight at Earths surface is 40% LESS than in Low Earth Orbit because
> of the thickness of our atmosphere (orbital solar flux in the visible
> range is over 1.4 kw/m^2, sea level solar flux is about 1.0 kw/ 
> m^2). As
> Mars' atmosphere is quite thin, only about 6 millibars, it does not
> attenuate Mars orbit solar flux by a significant percent. Therefore it
> follows that the brightness of sunlight on the surface of Mars is
> relatively close to that on the surface of Earth.
>
> You are otherwise correct vis a vis Jupiter and Saturn.
>
> Mike Lorrey
> Vice-Chair, 2nd District, Libertarian Party of NH
> "Necessity is the plea for every infringement of human freedom.
> It is the argument of tyrants; it is the creed of slaves."
>                                       -William Pitt (1759-1806)
> Blog: http://intlib.blogspot.com
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam?  Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
> _______________________________________________
> extropy-chat mailing list
> extropy-chat at lists.extropy.org
> http://lists.extropy.org/mailman/listinfo/extropy-chat
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.extropy.org/pipermail/extropy-chat/attachments/20050730/fb2a0503/attachment.html>