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1500 questions
26
votes
1 answer
Is lithium considered a metal in astronomy?
My lecture notes are conflicting on this issue so I seek definitive clarification. In Astronomy, are metals either
A: the elements which form within stars (i.e., not Big Bang nucleosynthesis, where most of the lithium (Li) was formed as far as I…
zabop
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26
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2 answers
How often do stars pass within 1 light year of the Sun?
Interstellar exchange of massive objects is difficult across several light years. But as the stars orbit the galaxy the distances between them change. I don't find data for neighbor star distances which covers more than a couple of a hundred…
LocalFluff
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26
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7 answers
If the Moon were impacted by a suitably sized meteor, how long would it take to impact the Earth?
An answer to the question of How well would the Moon protect the Earth from a Meteor? mentions as a possibility that the Moon could get knocked into the Earth.
What is the smallest change to the orbit of the Moon from being impacted by a large…
gilliduck
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26
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4 answers
What would happen if someone had a telescope and watched Betelgeuse when it goes supernova?
Would that person go blind?
Neutrino detectors and the abundance of Neutrinos would detect the upcoming visible show about 3 hours before any visible signs, so there would be time to point certain telescopes that could handle the brightness…
userLTK
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26
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1 answer
Are there more stars in the universe than grains of sand in the Earth?
My ten year old daughter asked me this question at breakfast and I initially said yes, but on second thought I was also puzzled.
Ruy
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26
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2 answers
Which atom is a Neutron star made of?
I understood that everything was made of Atoms.
An atom is the smallest constituent unit of ordinary matter that has
the properties of a chemical element. Every solid, liquid, gas, and
plasma is composed of neutral or ionized atoms
However…
James Wood
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26
votes
2 answers
Is it a coincidence that both the Sun and the Moon look of same size from the Earth?
The Sun is huge, when compared to the Moon. Despite the huge difference in their size and distance from Earth, is it purely coincidental that they both look almost the same from Earth?
Raj
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26
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2 answers
Why do stars explode?
I always hear the narrator of documentaries say that a star explodes because it ran out of fuel.
Usually things explode when they have too much fuel, not when they run out of fuel.
Please explain...
Lorry Laurence mcLarry
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26
votes
7 answers
How do we know the laws of physics are the same throughout the universe?
How do we know the laws of physics are the same throughout the universe? Intuitively I would say they would vary in two natural ways: the constants in the equations may vary or the math in the equations may vary. As a guess they could change over a…
qwerty10
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26
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3 answers
Are we made of the stuff of one star or more stars?
[T]his coincidence enabled stars in the late stages of their lives to turn helium into carbon, oxygen and most of the other atoms that you and I are made of. [...] [W]e're made of star stuff.
Max Tegmark, Our Mathematical Universe: My Quest for…
Řídící
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26
votes
1 answer
Why are there no green stars?
There are red stars, and orange stars, and yellow stars, and blue stars, and they are all understandable save the fact that there is a 'gap': There are no green stars.
Is this because of hydrogen's chemical properties (e.g. the emission spectrum)…
HyperLuminal
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25
votes
3 answers
Why is the Eagle Nebula so "static"?
This, of course, is a newbie question, as I am nothing more than a hobbyist. But I was quite surprised to see the recently-released "before and after" pictures of the so-called "Pillars of Creation" in the Eagle Nebula (here and here). For something…
kmote
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25
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3 answers
Why can't light escape from a black hole?
I've heard that light can't escape from a black hole. Can it? If not, why?
user19
25
votes
1 answer
Why are radio telescopes often built into natural depressions?
Radio telescopes are often built into sink holes or natural depressions in the landscape.* This is opposed to optical telescopes which are usually placed on mountains to avoid as much atmosphere as they can.
So why natural depressions? Is it easier…
joeyfb
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25
votes
2 answers
Was Galileo expecting to see so many stars?
Beginner amateur here. I see mentioned many times that Galileo was surprised to see the moons of Jupiter and all that their existence proved, i.e. the Earth not necessarily being the center of everything in the heavens. However I would think that…
Theodore
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