859 reputation
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bio website dotancohen.com
location
age 37
visits member for 1 year, 2 months
seen 5 hours ago

Oct
14
accepted Time period in which a planet rotates
Oct
14
comment Time period in which a planet rotates
Thank you Stan. I've been castrated more than once on English.SE for suggesting that a word's meaning could be inferred by its etymology. Apparently some people think that that term "living language" means "words mean whatever I want them to mean".
Oct
14
asked Time period in which a planet rotates
Oct
13
comment Can we see individual stars in other galaxies?
An event that occurs to a star.
Oct
13
comment Can we see individual stars in other galaxies?
In what way is a SN not a star? You could argue that a SN is a short-lived phase of a star, and I would agree with that. But for purpose of this discussion, in which the asker is interested in seeing spheres of fusing elements in other galaxies, a SN fits the description.
Oct
12
answered Can we see individual stars in other galaxies?
Oct
9
awarded  Yearling
Sep
16
comment How many astronomers are there in the world today?
Would you consider me an astronomer? I'm a software developer by trade, with no formal astronomy education besides university physics. I'll tell you the names, distances, masses, and other information of most celestial objects with an absolute magnitude 3 or higher. I'll teach you quite a bit about theories including orbital mechanics, astrophysics, gravitation, and also about practicalities such as historical and current spacecraft and missions. If you consider me as an astronomer despite no formal training, then any estimate of amount of astronomers goes way up, there are many more like me.
Sep
4
comment How is space-time bent by black holes?
Exactly. For spherical objects the gravity felt depends on only the mass of the object and the distance from it's center (squared). Black holes are assumed to be spherical.
Sep
4
comment How is space-time bent by black holes?
Actually, you can get nearer to the geometric center of the mass, which accounts for the higher local gravity field (and tidal forces). Note that at the same distance from the (center) of the black hole and the (center) of the star, the black hole's gravity will be lower.
Jul
28
comment Escaping a black hole
Mitchell, you might want to accept the answer as given. It answers your question very well.
Jun
10
comment How does the evolution of a solar system not break the second law of thermodynamics?
The statement "the radiated photons are out there somewhere" really does make it clear.
Jun
10
comment How does the evolution of a solar system not break the second law of thermodynamics?
So where was the corresponding increase in entropy to offset the creation of the solar system? Heat loss?
May
5
comment What would happen if an ice cube is left in space?
This is a terrific answer.
May
1
comment Would a Phobos full impact make Mars temporary habitable?
I am intrigued and I wish to subscribe to your newsletter.
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