Re the discussion about 3 kochavim beinonim: When I learned in 
Ponevez, I heard b'shem the Chazon Ish (who was still alive at the 
time) that when one sees ten stars, it means that there are three 
beinonim.

     As for the comment that "there are places where even shkias 
hachama doesn't happen," it depends on how one looks at it. At the 
pole, in summer, the sun rises in the sky until it reaches a high 
point, then starts setting until it reaches a low point, twenty-four 
hours after the rise began, then starts rising again.  Though the sun 
is always in the sky, it might be justified to consider as sh'kias 
hachama the moment when the setting ends and the rising begins.  
Certainly, it would seem that that is the moment the date changes.  I 
don't know what the metzius is during the six-month night.

EMT