See stars during daylight?

My father tells me he remembers talking to a miner who told him he could see
the stars when looking up an air shaft in the mine, even during broad
daylight.

I have done some thinking on this and would like to know if I am on the
right track. I think he may be correct, if the air shaft where long enough.
The light from the sun (at any time other than midday) would strike the air
shaft at an angle and reflect to the other side of the shaft and so on down
the shaft, except that of course not all light would be reflected, the light
losing its strength with each pass. If the shaft were long enough negligible
light fromt he sun would reach the bottom. A star directly over the shaft
however would cast light directly down the barrel, so to speak, and hence be
visible.

If my reasoning is correct, how long a tube will I need to erect in my back
yard to do some star-gazing during daylight?


--
35deg42'S; 174deg19'E

Doesn't work.

--

Don Baker


"s" wrote in message
...
My father tells me he remembers talking to a miner who told him he could
see
the stars when looking up an air shaft in the mine, even during broad
daylight.

I have done some thinking on this and would like to know if I am on the
right track. I think he may be correct, if the air shaft where long
enough.
The light from the sun (at any time other than midday) would strike the
air
shaft at an angle and reflect to the other side of the shaft and so on
down
the shaft, except that of course not all light would be reflected, the
light
losing its strength with each pass. If the shaft were long enough
negligible
light fromt he sun would reach the bottom. A star directly over the shaft
however would cast light directly down the barrel, so to speak, and hence
be
visible.

If my reasoning is correct, how long a tube will I need to erect in my
back
yard to do some star-gazing during daylight?


--
35deg42'S; 174deg19'E

Doesn't work.

--

Don Baker


"s" wrote in message
...
My father tells me he remembers talking to a miner who told him he could
see
the stars when looking up an air shaft in the mine, even during broad
daylight.

I have done some thinking on this and would like to know if I am on the
right track. I think he may be correct, if the air shaft where long
enough.
The light from the sun (at any time other than midday) would strike the
air
shaft at an angle and reflect to the other side of the shaft and so on
down
the shaft, except that of course not all light would be reflected, the
light
losing its strength with each pass. If the shaft were long enough
negligible
light fromt he sun would reach the bottom. A star directly over the shaft
however would cast light directly down the barrel, so to speak, and hence
be
visible.

If my reasoning is correct, how long a tube will I need to erect in my
back
yard to do some star-gazing during daylight?


--
35deg42'S; 174deg19'E

s wrote:

My father tells me he remembers talking to a miner who told him he could see
the stars when looking up an air shaft in the mine, even during broad
daylight.


Related URLs:

http://www.jesus.cam.ac.uk/college/flamsteed.htm
http://www.weatherman.com/wxastro6.htm

"Exactly what magnitude stars can be seen by day? Apparently the limit
runs from 1st to 4th magnitude, depending on the brightness of the sky.
The closer to sunrise, and sunset, the dimmer the stars that can be
detected. Indeed, several minutes before sunset [last fall, you could]
see many of Jupiter's moons through your scope! Can you see a shadow
crossing as well? I haven't tried it, but I bet you could!"

http://www.google.com/search?q=observing+stars+daytime

s wrote:

My father tells me he remembers talking to a miner who told him he could see
the stars when looking up an air shaft in the mine, even during broad
daylight.


Related URLs:

http://www.jesus.cam.ac.uk/college/flamsteed.htm
http://www.weatherman.com/wxastro6.htm

"Exactly what magnitude stars can be seen by day? Apparently the limit
runs from 1st to 4th magnitude, depending on the brightness of the sky.
The closer to sunrise, and sunset, the dimmer the stars that can be
detected. Indeed, several minutes before sunset [last fall, you could]
see many of Jupiter's moons through your scope! Can you see a shadow
crossing as well? I haven't tried it, but I bet you could!"

http://www.google.com/search?q=observing+stars+daytime

On Tue, 17 Feb 2004 22:21:55 +1300, "s" wrote:

If my reasoning is correct, how long a tube will I need to erect in my back
yard to do some star-gazing during daylight?

About 50 km should do it.

On Tue, 17 Feb 2004 22:21:55 +1300, "s" wrote:

If my reasoning is correct, how long a tube will I need to erect in my back
yard to do some star-gazing during daylight?

About 50 km should do it.

In article , says...

My father tells me he remembers talking to a miner who told him he could see
the stars when looking up an air shaft in the mine, even during broad
daylight.

If that's true then why shouldn't a telescope work in the middle of the day?
Afterall, the mirror is at the bottom of a dark tube?

I can imagine that a miner who's been in the dark all day long might see a
nearly dark sky as daylight.

Glenn

In article , says...

My father tells me he remembers talking to a miner who told him he could see
the stars when looking up an air shaft in the mine, even during broad
daylight.

If that's true then why shouldn't a telescope work in the middle of the day?
Afterall, the mirror is at the bottom of a dark tube?

I can imagine that a miner who's been in the dark all day long might see a
nearly dark sky as daylight.

Glenn

"s" wrote in message
...
My father tells me he remembers talking to a miner who told him he could
see
the stars when looking up an air shaft in the mine, even during broad
daylight.

I have done some thinking on this and would like to know if I am on the
right track. I think he may be correct, if the air shaft where long
enough.
The light from the sun (at any time other than midday) would strike the
air
shaft at an angle and reflect to the other side of the shaft and so on
down
the shaft, except that of course not all light would be reflected, the
light
losing its strength with each pass. If the shaft were long enough
negligible
light fromt he sun would reach the bottom. A star directly over the shaft
however would cast light directly down the barrel, so to speak, and hence
be
visible.

If my reasoning is correct, how long a tube will I need to erect in my
back
yard to do some star-gazing during daylight?
This is a very common 'misbelief'. A deep shaft, helps a _tiny_ amount. I
have (for instance), seen Jupiter, early in an evening, from the bottom of a
well, while it did not become visible at ground level till about half an
hour latter. This is because the narrow 'field' of the well/shaft, reduces
the ambient light entering your eyes, _but_ the shaft does not decrease the
actual background 'skyglow' from any particular part of the sky. The
'target', has to be brighter than this background to be seen. In the
daytime, only the very brightest objects (Venus, Jupiter etc.), are bright
enough to achieve this. To reduce this level, would require the 'shaft' to
pass up through a significant part of the atmosphere.
There are other effects that can lead to miners etc., claiming to have seen
stars. When at the bottom of a shaft, with the eyes well adapted to the
light, even a tiny object, like a moth, flying across the top of the shaft,
and illuminated by sunshine, can give a 'speck' of light, that appears like
a star.
It is not direct 'sunlight', that you have to worry about, but the glow in
the sky, caused by Rayleigh scattering of the light (which is why the sky is
blue).

Best Wishes