560 reputation
17
bio website dotancohen.com
location
age 37
visits member for 1 year
seen Oct 21 at 10:09

Feb
5
awarded  Nice Question
Jan
9
answered Are nebulae only visible from a distance?
Dec
27
comment How would the night sky look from inside a globular cluster?
The Asimov story Nightfall describes this very situation.
Dec
16
comment Doesn't gravity attract objects in space until they collide?
@Envite: Thanks. I edited the post to remove that simplification with a better, more accurate, simplification.
Dec
16
revised Doesn't gravity attract objects in space until they collide?
added 8 characters in body
Dec
9
comment Could any known, living organisms on Earth survive on Mars?
No problem! I'm also hoping to see some other interesting answers.
Dec
6
answered Could any known, living organisms on Earth survive on Mars?
Nov
24
comment Can I see comet ISON from Saudi Arabia?
Very nice, Astro! Thanks!
Nov
24
comment How would I measure that I'm at a pole?
That is a beautiful last picture, especially how the trails and the roofline are parallel.
Nov
24
accepted How would I measure that I'm at a pole?
Nov
21
awarded  Commentator
Nov
21
comment Doesn't gravity attract objects in space until they collide?
@astromax: Right, but that is in addition to the momentum component of the orbiting body (assuming m<<M). Otherwise, as the OP stated, the objects would collide.
Nov
21
comment Can I see comet ISON from Saudi Arabia?
On what basis do you calculate the absolute magnitude of the cometary system? Surely not as a rocky object I hope! Don't forget that the coma and tail are mostly empty space, thus there is no crescent and the light is very diffuse. You would need to know the amount of particles in the material as well, which we don't know. Even the albedo of the particles we don't know as we don't know which type of particles there will be (ice, methane, etc.).
Nov
21
revised How can only 1 magnetic pole of the Sun change at a time?
added 625 characters in body
Nov
21
revised Doesn't gravity attract objects in space until they collide?
added 15 characters in body
Nov
21
comment Can I see comet ISON from Saudi Arabia?
@AstroFloyd: Please put that up on Github! I would love to see that, no matter what language it is written in.
Nov
21
awarded  Teacher
Nov
21
comment Can I see comet ISON from Saudi Arabia?
I also highly recommend Stellarium.
Nov
21
comment Can I see comet ISON from Saudi Arabia?
By 'most visible' I infer the greatest visual magnitude difference between light originating from the comet components (nucleus, coma, tail) to between sunlight reflected from out atmosphere or direct from the Sun.
Nov
21
awarded  Editor