David Williams
May29-04, 11:59 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>-> At the midnight, there is almost no light coming from the Sun - it is\n-> difficult for light to get here, even for the light rays that can be\n-> reflected (because the atmosphere only exists tens of kilometers above the\n-> Earth\'s surface, and you would need multiple reflections of the light\n-> which is unlikely) - and the "no light" color is called "black".\n\nIf I wear a blue shirt, and go out at night, does the shirt become\nblack?\n\nIn a sense, it does. Since no light (or very little) is striking the\nshirt, anyone who looks at it will see only blackness. But in another\nsense the shirt remains blue. Even though the total amount of light is\nvery small, it is still true that the shirt reflects a greater fraction\nof the blue light that strikes it than any other colour. If a\nphotograph were taken of it with an extremely long exposure time, so\nthat the tiny amount of light is integrated for long enough that the\nfilm (or CCD) is affected properly, the photograph would show the shirt\nto be blue.\n\nI suppose the same is true of the night sky, although I have never seen\nthe experiment done. An extremely long-exposure photograph, made by\nmoonlight or even starlight, would show the sky to be blue.\n\ndow\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>-> At the midnight, there is almost no light coming from the Sun - it is
-> difficult for light to get here, even for the light rays that can be
-> reflected (because the atmosphere only exists tens of kilometers above the
-> Earth's surface, and you would need multiple reflections of the light
-> which is unlikely) - and the "no light" color is called "black".
If I wear a blue shirt, and go out at night, does the shirt become
black?
In a sense, it does. Since no light (or very little) is striking the
shirt, anyone who looks at it will see only blackness. But in another
sense the shirt remains blue. Even though the total amount of light is
very small, it is still true that the shirt reflects a greater fraction
of the blue light that strikes it than any other colour. If a
photograph were taken of it with an extremely long exposure time, so
that the tiny amount of light is integrated for long enough that the
film (or CCD) is affected properly, the photograph would show the shirt
to be blue.
I suppose the same is true of the night sky, although I have never seen
the experiment done. An extremely long-exposure photograph, made by
moonlight or even starlight, would show the sky to be blue.
dow
-> difficult for light to get here, even for the light rays that can be
-> reflected (because the atmosphere only exists tens of kilometers above the
-> Earth's surface, and you would need multiple reflections of the light
-> which is unlikely) - and the "no light" color is called "black".
If I wear a blue shirt, and go out at night, does the shirt become
black?
In a sense, it does. Since no light (or very little) is striking the
shirt, anyone who looks at it will see only blackness. But in another
sense the shirt remains blue. Even though the total amount of light is
very small, it is still true that the shirt reflects a greater fraction
of the blue light that strikes it than any other colour. If a
photograph were taken of it with an extremely long exposure time, so
that the tiny amount of light is integrated for long enough that the
film (or CCD) is affected properly, the photograph would show the shirt
to be blue.
I suppose the same is true of the night sky, although I have never seen
the experiment done. An extremely long-exposure photograph, made by
moonlight or even starlight, would show the sky to be blue.
dow