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1500 questions
43
votes
3 answers
Why did Venus not lose its atmosphere without a magnetic field?
It is often stated that the magnetosphere not only shields the planet from cosmic radiation, but also prevents atmospheric loss. Why then did Venus not lose most of its atmosphere if it doesn't have a strong magnetic field? Is there another…
Irigi
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42
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3 answers
How did Hubble know the red shift difference between "moving away" and "old"?
My 9yo daughter is very into space at the moment and asked a question that my physics knowledge (6th form college, 20 years ago) is way too poor to answer.
Her space book tells us that as stars age, they get redder. On the next page, it tells us…
Whelkaholism
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42
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2 answers
Are new stars less pure as generations go by?
If stars are primarily made of hydrogen, which is then burned to helium, and then on and on and on down the chain until you either reach iron, or in extreme cases much heavier metals, this then implies that as time goes on, more and more heavy…
Electric Coffee
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42
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1 answer
Closest star system to Alpha Centauri?
The closest star system to our Solar System is Alpha Centauri.
But is our Solar System the closest star system to Alpha Centuari?
If not, which star system is?
badroit
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42
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1 answer
Is Earth's moon the only one where a total eclipse of the sun covers the entire sun?
Is Earth's moon the only one where a total eclipse of the sun covers the entire sun?
Are any other moons the same size as the sun as viewed from their planet like Earth's moon?
MB34
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42
votes
5 answers
How old is the oldest light visible from Earth?
Because light can only travel so fast, all of the light we see in the sky was emitted at a previous moment in time. So if for example we see a supernova or some other great stellar event, by the time we see it, it maybe long over. That made me…
Mark Rogers
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42
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2 answers
Where can I find the positions of the planets, stars, moons, artificial satellites, etc. and visualize them?
What resources are available to find the positions of planets, stars,
moons, artificial satellites, asteroids, and other heavenly bodies?
user21
41
votes
3 answers
Do moons have moons?
Have we discovered any natural satellites of natural satellites of planets or dwarf planets? Even very small, or relatively short-lived - e.g. ringlets around Saturn's moons, some meteorites orbiting Jupiter moons, or something to orbit Charon? Or…
SF.
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41
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2 answers
Do all stars have an Oort cloud or is it a rare occurence?
Do all stars have an Oort cloud like ours that will be filled with comets and other objects? If not, why are they not around every star?
06needhamt
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41
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3 answers
Why are there uneven bright areas in this photo of black hole?
In the recently released photo of a black hole shown above, which was created by using data from EHT, why is the lower region brighter than the one above? Is it because of the rotation of the accretion disk? Also what is the orientation of the…
Kushal Bhuyan
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41
votes
5 answers
How are black holes found?
Black holes have so much gravity that even light can't escape from them. If we can't see them, and the suck up all electromagnetic radiation, then how can we find them?
user19
41
votes
4 answers
Can the moon appear to be in any position in the sky?
It seems to me that the Moon has appeared in many locations - apparent locations - in the 'dome of the sky'. I know that the Sun follows an arc from east to west and that the arc is smaller in winter than in summer. Therefore the Sun cannot appear…
Donagh McCarthy
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41
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2 answers
How do I calculate the inclination of an object with an amateur telescope?
Suppose I would like to calculate the inclination of a satellite from the ecliptic. Would it be possible to do this with an amateur telescope? How would I go about doing so?
Note: A good answer should tell what kind of telescope an amateur would…
called2voyage
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40
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3 answers
How do scientists know that the distant parts of the universe obey the physical laws exactly as we observe around us?
How do scientists know that distant parts of the universe obey the physical laws exactly as we observe around us?
The question might look a bit odd but I am really stuck on my head. We know, scientists (with tools) explored physically only our solar…
Sazzad Hissain Khan
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40
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5 answers
Why can't we see Saturn's phases from earth?
In the Astronomy Picture of the Day from August 8, 2020 ("Crescent Saturn"), the caption states
From Earth, Saturn never shows a crescent phase
Why is this? We can observe phases on planets such as Venus which have an apparent size a lot smaller…
jng224
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