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1500 questions
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3 answers
Why do massive stars not undergo a helium flash
I understand that for low-mass stars the helium flash occurs due to their degenerate helium cores. Thus the answer to this question is probably that more massive stars do not have a degenerate core, but I do not understand why they wouldn't. Due to…
Kristian
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Is the water underneath Europa's ice cap potable?
I read this question on Worldbuilding.SE, and figured that the astronomy site would have answers too, particularly for the specific example of Europa. The idea is that Earth's oceans are salty because rain falls on continents, and while the rain…
KeizerHarm
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Intuition about why gravity is inversely proportional to exactly square of distance between objects
What is the intuition behind why gravity is inversely proportional to exactly square of distance between two object and not cube or not some multiplier. Basically how Newton came up that its exactly square of distance? How it was validated it is in…
jrp
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18
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What will the PRECISE time of the Summer Solstice 2020 be?
I'm trying to explain to my daughter that the Summer Solstice is not a day of the year, but an exact instant in time. My search shows that this will be about 21:43 or 21:44 UTC tonight. To make my point I searched for a more precise time. I…
David Dubois
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18
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2 answers
Does the Moon have any oxygen in its atmosphere?
Since the moon has gravity, it's almost impossible that there aren't some gasses trapped on the surface by the moon's gravity. Has any free-floating oxygen been found on the Moon? If so, in what concentration?
user19
18
votes
2 answers
Did nobody in the Astronomy community think 12,000 new satellites in LEO might be a problem?
This answer to Can / should the Starlink satellites be blackened? mentions Space News' SpaceX working on fix for Starlink satellites so they don’t disrupt astronomy where SpaceX chief operating officer Gwynne Shotwell is quoted as saying the…
uhoh
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18
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4 answers
Are there any to-scale diagrams of the TRAPPIST-1 system?
Recommended to cross-post from SpaceEx: https://space.stackexchange.com/questions/38397/are-there-any-to-scale-diagrams-of-the-trappist-1-system
I was recently told that the planets in TRAPPIST-1 are close enough together that you can see them from…
Brondahl
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18
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5 answers
If all stars rotate, why was there a theory developed that requires non-rotating stars?
According to Penrose's research, a non-rotating star would end up, after gravitational collapse, as a perfectly spherical black hole. However, every star in the universe has some kind of angular momentum.
Why even bother doing that research if that…
Murg
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What is there in the intergalactic space?
What bodies can be encountered way outside galaxies - far beyond the farthest edges of galaxies, in the deep space between them? Are there single, galaxy-less stars, giant clouds of gas more dense than that the lower-than-elsewhere content of free…
SF.
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Why do astronauts move so slowly in zero gravity?
When astronauts are floating about in a spaceship or space station, they nearly always move very slowly. After doing a bit of research I can't see why being in zero gravity would restrict movement to such a degree. It's almost as if there's…
metaDesign
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Why don’t we feel the Earth rotating beneath us?
I’m not sure all of the details in the experiment but basically it went as follows. Someone marked their location of take off in a hot air balloon and went straight up in the air. They stayed suspended for some time before coming straight back down.…
Begons18
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3 answers
Does the rotation of galaxies precess?
Does the axis of a galaxy as a whole "wobble" the same way that the Earth does? If so do we have any idea how much or how fast the Milky Way is doing so?
smithkm
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18
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What does it mean for a star to go nova or supernova? Can I safely observe these?
What does it mean for a star when people say it goes 'nova' or super nova, what are the differences?
More importantly, can I safely observe these with an amateur telescope? I imagine they would be big enough to spot should one happen!
user96
18
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2 answers
When a star reaches the red giant phase, why does it become more opaque?
Please refer to this answer from Quora:
... a star will become a red giant before it begins burning helium. In fact, it will bloat into a red giant while still burning hydrogen in a shell on the surface of the helium core. Shell burning, however,…
Ian Kemp
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18
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3 answers
Energy loss from Doppler effect
The energy of electromagnetic radiation is related to frequency; higher the frequency, higher the energy level. If electromagnetic waves have lower frequency when they arrive on Earth than originally emitted due to the Doppler effect, where,…
Dilettanter
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