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1500 questions
37
votes
5 answers
How exactly does Hawking radiation decrease the mass of black holes?
From what I understand so far, when one of virtual particles crosses the event horizon and the other does not, they can not annihilate each other. The latter wanders off into the universe (btw, is it still virtual at this point, and what does…
marko-36
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37
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3 answers
What happens to the 99.9 % of the sun-rays that do not fall on any planets or any other celestial body?
I assume that about 99.9% of the sun-rays that do not fall on any planet or any other celestial body keep on traveling farther and farther unto infinity. Apparently such rays get lost. Keeping in mind the colossal energy Sun has produced since 4.5…
S C Sawhney
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37
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2 answers
Why doesn't the moon twinkle?
Stars twinkle because their light has to squeeze through several different layers of the Earth's atmosphere. So why doesn't the moon twinkle as well?
Ricky
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37
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4 answers
How can we tell that the Milky Way is a spiral galaxy?
From Earth, we can distinguish the type of another galaxy very easily simply by observing the shape, colour, and structure of the galaxy when we image it. But since we are located inside the Milky Way, we cannot get an "outside view". Thus, how can…
Devgeet Patel
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36
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2 answers
Why does the alignment evaluation image from JWST look like this?
NASA has just released a telescope alignment evaluation image from JWST for the star HD 84406 2MASS J17554042+6551277. It looks like this:
Higher resolution at Wikipedia
To my untrained eye, the star looks like it would look when viewed from a…
RedBaron
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36
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2 answers
How was the mass of Venus determined?
The mass of Venus seems rather complicated to determine to me:
Venus doesn't have any satellites, so you can't just apply Kepler's third law (like you would with Jupiter or Saturn for instance) to determine its mass.
The gravitational tug of Venus…
usernumber
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36
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5 answers
Can small gas planets exist?
Most of the known gas planets (Jupiter, Saturn, etc.) are huge. They are even called "gas giants".
is it possible to exist a gas planet around the size of Earth? If yes, why; if no, why?
Zoltán Schmidt
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36
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3 answers
Why does Jupiter have so many moons?
Jupiter has a great many moons - in the hundreds, and they're still being discovered.
What is the current theory for where all these moons came from? Are they rocks flying through space captured by Jupiter's gravity?
user19
36
votes
1 answer
Considering our methods of exploration, how likely is it that there are unfound planets (not dwarf planets) in our solar system?
I think it's probably unlikely that there are more planets between Mercury and Mars, but out from Jupiter, there's lots of empty space between the planets. Could there be some small planet hidden out there?
harada
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36
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3 answers
Where did the Sun get hydrogen to work with if it is in the 3rd generation of stars?
As I see here, the Sun belongs to the Population I group of stars, which is the 3rd generation of the stars in our universe. 1st generation stars are Population III, 2nd generation are Population II, and 3rd generation are Population I.
When the 1st…
Zlelik
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36
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7 answers
What did LIGO Actually See? (Gravitational waves discovery)
I am trying to find an original video/image of what LIGO actually saw, but all I can find is artist renditions of gravitational waves.
Scott Taylor
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36
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1 answer
Why do the planets in our solar system orbit in the same plane?
(Yes I'm excluding Pluto from this the same way it was excluded for not being a planet)
Observing the planets orbit of the Sun they all seem relatively planar and roughly all orbit along the same plane.
Is this due to the way that our Solar system…
user96
35
votes
7 answers
What's the fastest moving object in the universe?
We know that nothing can have proper velocities larger than the speed of light in vacuum. But are there any objects in space that get close to it? Any comets, or other objects thrown by gravity or supernova explosions that were hurled to incredible…
bogen
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35
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3 answers
Can Pluto be seen with the naked eye from Neptune when Pluto and Neptune are closest?
When Neptune and Pluto are closest, about 100 million mi (160 million km) from each other, would an observer on Neptune (or rather on one of its moons, since Neptune is gaseous) be able to see Pluto, and maybe even Charon, with the naked eye? If…
Plutos Loyer
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35
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10 answers
Why doesn’t the Sun fill the sky on Mercury?
I’ve seen a lot of photos showing Mercury in front of the Sun when it passes by and you can see just how tiny it is in comparison.
Here’s a great example:
So I’d expect if I was travelling towards Mercury in that photo that as the planet got bigger…
Cameron
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