560 reputation
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bio website dotancohen.com
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age 37
visits member for 1 year
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Nov
21
revised Can I see comet ISON from Saudi Arabia?
deleted 1 characters in body
Nov
21
answered Can I see comet ISON from Saudi Arabia?
Nov
21
answered How can only 1 magnetic pole of the Sun change at a time?
Nov
21
answered Doesn't gravity attract objects in space until they collide?
Nov
21
comment How would I measure that I'm at a pole?
Thank you! I have read how Amundsen measured the Sun's altitude while searching for the South Pole, so obviously there exists a daytime method as well. However, I believe that he know which day of the year he was in, so he would know the expected changes in altitude due to the Earth's orbit around the sun.
Nov
20
asked How would I measure that I'm at a pole?
Nov
17
comment Might Oort cloud comets be exchanged between solar systems?
@Rory: Congrats on the 1000!
Nov
17
accepted Might Oort cloud comets be exchanged between solar systems?
Nov
17
comment Might Oort cloud comets be exchanged between solar systems?
The Oort cloud is about 1 LY from the sun, or 1/4 the distance to the current nearest star. That means that the gravitational pull of the current nearest star is 1/16 that of the sun: hardly insignificant. I don't believe that planets could have a stable orbit with that type of perturbation.
Nov
14
comment Might Oort cloud comets be exchanged between solar systems?
My line of thinking is that as stars pass one another on their way around the galaxy, they could 'brush' Oort clouds and thus exchange comets. The same mechanism may also perturb the comets to rain down on their own suns/stars.
Nov
13
asked Might Oort cloud comets be exchanged between solar systems?
Oct
31
awarded  Scholar
Oct
31
accepted How much did we know about asteroids at the beginning of the 20th century?
Oct
30
comment How much did we know about asteroids at the beginning of the 20th century?
Thank you. No matter which object Twain was referring to, he certainly knew enough to state that the asteroid is a huge object (compared to a hen's egg).
Oct
28
awarded  Student
Oct
28
asked How much did we know about asteroids at the beginning of the 20th century?
Oct
9
awarded  Supporter