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asked basic concepts about gamma ray burst
Dec
13
comment where is the boundary between dark night and grey night
@rob It is the total time the moon appears in some night divides the length of that night? Or it is the area of the moon divides the full moon's area?
Dec
12
comment where is the boundary between dark night and grey night
@Rob This correlates with the moonrise and moonset time, and the lunar phase. Grey night may have a period of time which is darker than dark night. BTW, What is FLI?
Dec
10
asked where is the boundary between dark night and grey night
Dec
10
accepted moonless night and lunar phase
Dec
10
comment The name of a particular low extinction region
good, this is the one I want to find.
Dec
10
accepted The name of a particular low extinction region
Dec
9
comment The name of a particular low extinction region
my bad. There should be a more famous window.
Dec
8
comment The name of a particular low extinction region
not this one. There are other astronomical items called XX window?
Dec
8
asked The name of a particular low extinction region
Nov
24
comment moonless night and lunar phase
So when the moon is in full moon phase, it could not make moonless night? And sometimes the moon may arise late in the night,before it arises, there is no moon in the sky and the sky is dark too. However a moonless night means there is no moon during a whole night, right?
Nov
24
asked moonless night and lunar phase
Nov
19
comment is there any theory or observational evidence that our universe is electrically neutral or not?
Is there any hypothesis that some galaxy could be un-neutral? Or even larger structure could be un-nrutral?
Nov
16
comment is there any theory or observational evidence that our universe is electrically neutral or not?
You mean it could be un-neutral in galactic scale? We do not care about time-scale here. Suppose there is an isolated galaxy which loses many of its electrons and can not get the electrons back for some kind of reason.
Oct
17
awarded  Yearling
Sep
27
accepted how did James Bradley discover light aberration?
Sep
26
comment how did James Bradley discover light aberration?
If a star's radial velocity changes in a short time, its visual position will change much? Say ,a short period black hole binary.
Sep
19
awarded  Teacher
Sep
17
reviewed Approve Which kind of properties can we get for cosmic ray particles hitting on an optical ccd?
Sep
16
comment the metal distribution in our solar system
@Joel you are answering my question?