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comment Does a self-gravitating gas necessarily develop turbulence?
I think turbulence is a hydrodynamics phenomenon and hence does not apply to dark matter. The dark-matter particles, though move much more chaotically, as intersecting streams are possible, unlike for gas.
Apr
22
revised Is there any way a meteor can hit at less than escape velocity?
address comment by OP
Apr
22
comment Is there any way a meteor can hit at less than escape velocity?
Indeed, you didn't clearly state what you meant.
Apr
13
revised Why do the planets in our solar system orbit in the same plane?
removed confusing link, added some explanation instead.
Mar
26
comment Is the motion of the Sun around the Galaxy a result of gravitational pull?
@RobJeffries I haven't followed this much recently, but 1/3 is significant, though perhaps not 'huge'. The details are still very much model dependent. The vertical motion is definitely anharmonic, though (because the density is not constant with z over the orbit of the Sun).
Mar
25
comment Would being ejected from the Milky Way Galaxy have any major impact on life on Earth?
The only realistic way to eject stars from a galaxy is by close encounters with a massive object (ideally a supermassive black hole - SMBH), which would certainly destroy the Solar system (unbind most planets) if this happens to the Sun (when it collides with M31s' SMBH in the merger).
Mar
25
comment Is the motion of the Sun around the Galaxy a result of gravitational pull?
@RobJeffries "There isn't thought to be a huge amount of dark matter interior to the Sun's orbit [...]" I'd thought that about half the mass interior to the orbit of the Sun is dark (that's not much as dark matter goes, but relative to the baryonic component it's certainly significant). For an exponential disc (as the baryonic parts of disc galaxies are observed to be), the rotation velocity peaks at 2.1 scale radii and drops thereafter. For the Milky Way that's interior to the Sun and there is no indication of a drop.
Mar
25
comment Initially non-flat space-time makes dark matter obsolete$\dots$
You may be able to explain away dark energy with inhomogeneities of space-time (which we know is reality, since matter is inhomogeneous, but this is usually ignored in cosmological models).
Feb
21
awarded  Nice Answer
Dec
18
awarded  Yearling
Nov
22
answered How can an infinite universe expand?
Oct
19
comment What were the 2 satellites I saw this morning?
I'm voting to close this question as off-topic because not about astronomy
Oct
19
comment What were the 2 satellites I saw this morning?
Almost certainly not astronomical objects.
Oct
19
comment Is the time lapse considered when estimating the age of the universe?
Which time-lapse are you referring to?
Oct
18
awarded  Revival
Oct
16
comment Two species of dark matter?
@RobJeffries I'm particularly concerned about the waste of brain, of which comparatively little is spend in the dark-matter 'industry'.
Oct
16
comment Two species of dark matter?
@RobJeffries thanks for your comment. I'm fully aware that dark matter is only still a hypothesis and hinges on the correctness of GR, which in turn is not experimentally verified on the relevant field strengths (or shall I say 'weakness'). The cuspiness issue is not a fundamental problem, as its prediction ignores baryonic effects, which must play a role on small scales. Moreover, on galaxy-cluster scales, the cusps are there (the mass profile in the outer parts of central-cluster galaxies is what we expect for the inner parts of the cluster halo).
Oct
15
comment Two species of dark matter?
@AlexeyBobrick There is zero evidence for supersymmetry. AFAIK, supersymmetry has not made a single falsifiable prediction that was later verified. Supersymmetry is a classiacal WOMBAT (= Waste Of (tax payer's) Money, Brain, And Time).
Oct
15
revised Two species of dark matter?
added 12 characters in body
Oct
14
revised Two species of dark matter?
added 208 characters in body