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seen Dec 11 at 10:16

Dec
11
comment Without using absolute magnitudes or isochrones, how might we tell a star's age and evolutionary status?
The spectrum mathcing technique consists in comparing the spectrum being investigated with a library of spectra of known age, size, metallicity and evolutionary status. Guess where these data came from?
Dec
11
comment Could Venus be a source of Earth's water?
If they were in orbits, we would almost never collect them, unless their orbits crossed ours. Those particles with orbits minor or major than Earth's would never be captured!
Dec
11
comment How can astronomers determine the difference between “hydrostatic equilibruim” and “just happens to be spherical”?
@dotancohen Do not trust Wikipedia so much. I may be wrong, but this is what I learnt at University.
Dec
11
comment How can astronomers determine the difference between “hydrostatic equilibruim” and “just happens to be spherical”?
If the dominant force were gravity, all objects would be black holes. Since they are not, it means that objects have equilibrium. It just happens that for non-gas bodies it is not hydrostatic equilibrium.
Dec
4
comment time on earth compared to completely stationary in space
Remember that, while there are no stationary reference frames, it is clear that ORBITING reference frames are not valid as inertial reference frames and ALWAYS have a dilation on their own due to that.
Dec
4
comment time on earth compared to completely stationary in space
This answer is not completely correct. In ANY rest frame the Earth is moving around the Sun, because this movement is not rectilinear.
Dec
4
answered How can astronomers determine the difference between “hydrostatic equilibruim” and “just happens to be spherical”?
Dec
4
answered What is the long term fate of the gas giants?
Dec
4
comment What is the long term fate of the gas giants?
Please do not use words like "trillion" since they are confusing. It does not convey the same sense in the en.wikipedia.org/wiki/Long_and_short_scales Please use clear scientific words like Gigayears.
Dec
4
comment Without using absolute magnitudes or isochrones, how might we tell a star's age and evolutionary status?
You say: "You can plot the star in the log g vs Teff plane and compare it with theoretical isochrones appropriate for the star's metallicity." so you are using isochrones. The question is "Without using isochrones".
Dec
3
comment Without using absolute magnitudes or isochrones, how might we tell a star's age and evolutionary status?
@RobJeffries which other ways that are not indirectly based on isochrones?
Dec
1
answered What are the nearest galaxies I can observe?
Dec
1
comment Roche Limit for Earth-like body around Earth-like body
@Py-ser True, it does not answer it, because Earth is not exactly rigid (no celestial body is).
Nov
27
awarded  Student
Nov
26
comment Roche Limit for Earth-like body around Earth-like body
Wikipedia gives generalities as "Rigid" and "Fluid" but not an actual distance for Earth near Earth. It gives not even a single figure for Moon near Earth.
Nov
26
comment Roche Limit for Earth-like body around Earth-like body
How much? I want to know which is the distance for such a Roche Limit, please.
Nov
24
comment moonless night and lunar phase
Depending on your horizon and the quality of your instruments, you may have three moonless nights. Check en.wikipedia.org/wiki/Hilal_(crescent_moon)
Nov
24
asked Roche Limit for Earth-like body around Earth-like body
Nov
22
awarded  Yearling
Oct
29
comment What happens to photons that don't interact with something?
Some simple maths show a photon frecuency approaches zero asintotically, so it will never reach that.