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1500 questions
69
votes
5 answers
Why is there a zig-zag in elemental abundances?
In this answer to Is lithium considered a metal in astronomy? this image from Wikimedia of the abundances of elements in the universe was shared:
Credit: Wikimedia Commons user 28bytes, under C.C.-by-S.A.-3.0.
I thought it was fascinating that…
curiousdannii
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67
votes
2 answers
If two black hole event horizons overlap (touch) can they ever separate again?
Hypothetical question based on my understanding that two event horizons that overlap (touch) can't ever separate again:
Imagine a 1 billion solar mass black hole (so the event horizon is massive and very gravitationally weak) is travelling at a…
Loadwick
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63
votes
1 answer
Why is the asteroid belt shaped like a triangle?
So, in this question, the user JollyJoker posted this image depicting the orbits of the asteroids in the asteroid field in the comments:
[
In this image, you can see that while the individual asteroids follow elliptical orbits, the asteroid belt as…
nick012000
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62
votes
3 answers
What is the hottest thing in the universe?
Straight from my 7 year old to you, exactly what it says on the cover:
What is the hottest thing in the universe?
To make it Stack Exchange-friendly, I'll add the following caveats:
it should be bounded, as in an actual compact object, or class…
Bruce Becker
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62
votes
6 answers
Why hasn't the "9th Planet" been detected already?
In the comments to this question, there was considerable doubt placed as to the subject of if the so called "9th planet" really exists. That wasn't really the intent of the previous question, so I ask this. Why hasn't this "9th planet" been detected…
PearsonArtPhoto
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61
votes
7 answers
How many planets are there in this solar system?
So, in school (that's a long time ago) they have been teaching us there are 9 planets in our solar system.
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
But every now and then I keep reading stories about another "dwarf planet"…
e-sushi
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60
votes
5 answers
When will the Sun end all human life on Earth?
If nothing else wipes out human existence prior to this, at what point will the Sun make Earth uninhabitable for humans?
Daniel Storm
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59
votes
6 answers
Why does Io cast a hard shadow on Jupiter, but the Moon casts a soft shadow on Earth?
Io (source):
The Moon (source):
stackzebra
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59
votes
2 answers
Would we have more than 8 minutes of light, if the Sun "went out"?
The common theory is, that if the Sun "shut down", we would see the light for eight more minutes (the time that it takes the photons to reach the Earth).
However recently I have read that photons need around 100,000 years to reach the Earth, since…
Murg
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58
votes
3 answers
Where did TRAPPIST-1a go?
According to the NASA announcement and the Wikipedia article on TRAPPIST-1, the planets around the TRAPPIST-1 star are named TRAPPIST-1 b through h. What happened to "TRAPPIST-1 a"?
Guss
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57
votes
2 answers
Why has Venus's atmosphere not been stripped away by solar wind?
This answer on Space Exploration to a question about Mars says that one reason Mars has such a thin atmosphere is because it lacks a magnetic field to protect it from the effect of double solar winds.
Here MBR explains that Venus does not have a…
called2voyage
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57
votes
4 answers
How did Astronomers deduce that the Sun was not a ball of fire?
Its common knowledge that people used to think that the sun is a ball of fire or molten metal, but when did science start to prove otherwise?
Krish
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56
votes
2 answers
Sun constantly converts mass into energy, will this cause its gravity to decrease?
If the sun is constantly converting the mass into energy, then will its gravitational field continue decreasing?
Mohan Mone
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56
votes
6 answers
If light has no mass, why is it affected by gravity?
Light doesn’t accelerate in a gravitational field, which things with mass would do, because light has a universally constant velocity. Why is that exception?
Rahul Singh
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55
votes
9 answers
Does matter accumulate just outside the event horizon of a black hole?
My understanding is that time slows and approaches stopping when approaching the event horizon of a black hole. I have seen this explained several places, including a brief explanation in the last paragraph under:…
Jonathan
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