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bio website dotancohen.com
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age 37
visits member for 3 years, 3 months
seen 8 hours ago

Jun
9
comment Can human push earth away from the sun?
Actually, there is nothing confusing about it. At the point in the orbit where you apply the acceleration the Earth will be moving faster. On the other side of the orbit the Earth will be moving slower, though. Of course, the distance from the Sun at that point will be larger, and that is where you see the extra energy. You can then perform a second manoeuvre at that slower, further point to push the opposite (closer, faster point) out further from the Sun.
Jun
9
awarded  Editor
Jun
9
comment Can human push earth away from the sun?
@Xiè: It is not a matter of efficiency but rather changing the shape (eccentricity) of the orbit and therefore the distance from the Sun (two manoeuvres). You should read the linked article on orbital mechanics.
Jun
9
revised Can human push earth away from the sun?
added 64 characters in body
Jun
9
comment Can human push earth away from the sun?
Thanks, Bill, you are right. The Sun will turn into a red giant, not nova. I'm all embarrassed now!
Jun
8
reviewed Approve suggested edit on Is it possible that I just saw Jupiter's moons?
Jun
8
comment Do any naked-eye stars have planets
Perfect! This is exactly what I was looking for. Thanks! The list does seem incomplete, thought as Fomalhaut is missing.
Jun
8
accepted Do any naked-eye stars have planets
Jun
8
answered Can human push earth away from the sun?
Jun
8
asked Do any naked-eye stars have planets
Jun
5
reviewed Approve suggested edit on Confusing description of Orions belt, could someone clarify?
May
13
comment Is the environment around an asteroid harsher than in interplanetary space?
Thank you. I suppose that you meant conduction, not induction, and I suppose that is possible. I know that lying on cold ground sure makes me cold. Thanks.
May
13
comment Is the environment around an asteroid harsher than in interplanetary space?
Thanks, Qmechanic. I deleted the offending tags.
May
13
revised Is the environment around an asteroid harsher than in interplanetary space?
edited tags
May
13
asked Is the environment around an asteroid harsher than in interplanetary space?
Mar
24
accepted Why is Jupiter so sharply defined?
Mar
21
comment Why is Jupiter so sharply defined?
Thanks. Looking through the paper I see lots of formulae with r^2 but nothing that would suggest a sharp cutoff, such as (r-n)^2 or the like. Where is there mention of a sharp cut off for the pressure and density at some specific r? Thanks for the reference, it does seem to address quite what I am asking about.
Mar
20
comment Lowest gravity on Earth's surface?
The colour coding of GRACE is fine. The lack of an X to mark the lowest point is my question.
Mar
20
comment Lowest gravity on Earth's surface?
Thank you. I did see that, but as you mention it does not pertain to the entire Earth's surface but rather only to the relatively small portions of the Earth's surface which constitute large human population centers.
Mar
20
comment Why is Jupiter so sharply defined?
I agree that the image that I posted was edited. For one thing, the phases of Jupiter and Io are different though their centers lie in about the same camera direction.