Stars visible from Mars in the daytime?

Anyone have a clue as to whether many stars are visible from Mars
during the day? It seems to me that the very thin atmosphere combined
with a fainter sun would make this easily possible. Just for
curiosity's sake. :-)

Ritesh

(Axel) wrote in message . com...
Anyone have a clue as to whether many stars are visible from Mars
during the day? It seems to me that the very thin atmosphere combined
with a fainter sun would make this easily possible. Just for
curiosity's sake. :-)

The Sun is about half as bright from Mars as it is from Earth; the
difference would be hardly perceptible to us--if at all. (Have you
ever experienced a partial solar eclipse?) I don't know enough to
comment about the thinner, but dustier atmosphere.

Even if it is possible to see stars, it would be much more difficult
than you'd expect. Think about how difficult it is to see stars at
night after walking out of a brightly lit room. Consider that Mars in
the day is incomparably more brightly lit than your living room at
night.


Clear skies!

--
------------------- Richard Callwood III --------------------
~ U.S. Virgin Islands ~ USDA zone 11 ~ 18.3N, 64.9W ~
~ eastern Massachusetts ~ USDA zone 6 (1992-95) ~
--------------- http://cac.uvi.edu/staff/rc3/ ---------------

(Axel) wrote in message . com...
Anyone have a clue as to whether many stars are visible from Mars
during the day? It seems to me that the very thin atmosphere combined
with a fainter sun would make this easily possible. Just for
curiosity's sake. :-)

The Sun is about half as bright from Mars as it is from Earth; the
difference would be hardly perceptible to us--if at all. (Have you
ever experienced a partial solar eclipse?) I don't know enough to
comment about the thinner, but dustier atmosphere.

Even if it is possible to see stars, it would be much more difficult
than you'd expect. Think about how difficult it is to see stars at
night after walking out of a brightly lit room. Consider that Mars in
the day is incomparably more brightly lit than your living room at
night.


Clear skies!

--
------------------- Richard Callwood III --------------------
~ U.S. Virgin Islands ~ USDA zone 11 ~ 18.3N, 64.9W ~
~ eastern Massachusetts ~ USDA zone 6 (1992-95) ~
--------------- http://cac.uvi.edu/staff/rc3/ ---------------

(Axel) wrote in message . com...
Anyone have a clue as to whether many stars are visible from Mars
during the day? It seems to me that the very thin atmosphere combined
with a fainter sun would make this easily possible. Just for
curiosity's sake. :-)

The Sun is about half as bright from Mars as it is from Earth; the
difference would be hardly perceptible to us--if at all. (Have you
ever experienced a partial solar eclipse?) I don't know enough to
comment about the thinner, but dustier atmosphere.

Even if it is possible to see stars, it would be much more difficult
than you'd expect. Think about how difficult it is to see stars at
night after walking out of a brightly lit room. Consider that Mars in
the day is incomparably more brightly lit than your living room at
night.


Clear skies!

--
------------------- Richard Callwood III --------------------
~ U.S. Virgin Islands ~ USDA zone 11 ~ 18.3N, 64.9W ~
~ eastern Massachusetts ~ USDA zone 6 (1992-95) ~
--------------- http://cac.uvi.edu/staff/rc3/ ---------------

I would suspect looking straight at the zenith at noon (from Mars) would allow
for a very bright but smaller sun with dark sky around it. One might be able
to see stars at higher elevations looking through the thin atmosphere with dark
sky. As one looked down further towards all horizons I suspect you would see a
blue or red sky such as from earth. It would be weird...especially standing in
Mars Mud!

I would suspect looking straight at the zenith at noon (from Mars) would allow
for a very bright but smaller sun with dark sky around it. One might be able
to see stars at higher elevations looking through the thin atmosphere with dark
sky. As one looked down further towards all horizons I suspect you would see a
blue or red sky such as from earth. It would be weird...especially standing in
Mars Mud!

I would suspect looking straight at the zenith at noon (from Mars) would allow
for a very bright but smaller sun with dark sky around it. One might be able
to see stars at higher elevations looking through the thin atmosphere with dark
sky. As one looked down further towards all horizons I suspect you would see a
blue or red sky such as from earth. It would be weird...especially standing in
Mars Mud!

In article , Cousin Ricky wrote:
(Axel) wrote in message . com...
Anyone have a clue as to whether many stars are visible from Mars
during the day? It seems to me that the very thin atmosphere combined
with a fainter sun would make this easily possible. Just for
curiosity's sake. :-)

The Sun is about half as bright from Mars as it is from Earth; the
difference would be hardly perceptible to us--if at all. (Have you
ever experienced a partial solar eclipse?) I don't know enough to
comment about the thinner, but dustier atmosphere.

Even if it is possible to see stars, it would be much more difficult
than you'd expect. Think about how difficult it is to see stars at
night after walking out of a brightly lit room. Consider that Mars in
the day is incomparably more brightly lit than your living room at
night.

But the Martian atmosphere is an awful lot thinner than ours -- its
surface pressure (6 millibars) is comparable to Earth's pressure at
an altitude of 25 miles! Even with all that pink lofted dust,
I'll bet the sky there is far darker than ours, much more than you'd
expect from the more distant sun.

Given that it's pretty easy to see Venus in a clear daytime sky on Earth
if you know where to look -- and it's ~100x brighter than a mag +1 star --
I wouldn't be surprised if a careful observer could pick out
a dozen or so stars in the Martian daytime sky.

A web search for "martian sky photometry" turned up some paper abstracts,
of which the most recent seems to be "JGR 104 (1999)". Maybe that's
Journal of Geophysical Research? Anyway, it sounds as though they
include absolute sky-brightness measures made with Mars Pathfinder.
Then those could be compared with other measurements of Earth twilight
sky brightness. It could make a nice science-fair kind of project.

Stuart

In article , Cousin Ricky wrote:
(Axel) wrote in message . com...
Anyone have a clue as to whether many stars are visible from Mars
during the day? It seems to me that the very thin atmosphere combined
with a fainter sun would make this easily possible. Just for
curiosity's sake. :-)

The Sun is about half as bright from Mars as it is from Earth; the
difference would be hardly perceptible to us--if at all. (Have you
ever experienced a partial solar eclipse?) I don't know enough to
comment about the thinner, but dustier atmosphere.

Even if it is possible to see stars, it would be much more difficult
than you'd expect. Think about how difficult it is to see stars at
night after walking out of a brightly lit room. Consider that Mars in
the day is incomparably more brightly lit than your living room at
night.

But the Martian atmosphere is an awful lot thinner than ours -- its
surface pressure (6 millibars) is comparable to Earth's pressure at
an altitude of 25 miles! Even with all that pink lofted dust,
I'll bet the sky there is far darker than ours, much more than you'd
expect from the more distant sun.

Given that it's pretty easy to see Venus in a clear daytime sky on Earth
if you know where to look -- and it's ~100x brighter than a mag +1 star --
I wouldn't be surprised if a careful observer could pick out
a dozen or so stars in the Martian daytime sky.

A web search for "martian sky photometry" turned up some paper abstracts,
of which the most recent seems to be "JGR 104 (1999)". Maybe that's
Journal of Geophysical Research? Anyway, it sounds as though they
include absolute sky-brightness measures made with Mars Pathfinder.
Then those could be compared with other measurements of Earth twilight
sky brightness. It could make a nice science-fair kind of project.

Stuart

In article , Cousin Ricky wrote:
(Axel) wrote in message . com...
Anyone have a clue as to whether many stars are visible from Mars
during the day? It seems to me that the very thin atmosphere combined
with a fainter sun would make this easily possible. Just for
curiosity's sake. :-)

The Sun is about half as bright from Mars as it is from Earth; the
difference would be hardly perceptible to us--if at all. (Have you
ever experienced a partial solar eclipse?) I don't know enough to
comment about the thinner, but dustier atmosphere.

Even if it is possible to see stars, it would be much more difficult
than you'd expect. Think about how difficult it is to see stars at
night after walking out of a brightly lit room. Consider that Mars in
the day is incomparably more brightly lit than your living room at
night.

But the Martian atmosphere is an awful lot thinner than ours -- its
surface pressure (6 millibars) is comparable to Earth's pressure at
an altitude of 25 miles! Even with all that pink lofted dust,
I'll bet the sky there is far darker than ours, much more than you'd
expect from the more distant sun.

Given that it's pretty easy to see Venus in a clear daytime sky on Earth
if you know where to look -- and it's ~100x brighter than a mag +1 star --
I wouldn't be surprised if a careful observer could pick out
a dozen or so stars in the Martian daytime sky.

A web search for "martian sky photometry" turned up some paper abstracts,
of which the most recent seems to be "JGR 104 (1999)". Maybe that's
Journal of Geophysical Research? Anyway, it sounds as though they
include absolute sky-brightness measures made with Mars Pathfinder.
Then those could be compared with other measurements of Earth twilight
sky brightness. It could make a nice science-fair kind of project.

Stuart