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Why is Mars cold?
The surface temperatures of Mars are about -87C to 5C, which is much colder than that of Earth's.
If Mars has 95% carbon dioxide, which is a Greenhouse gas, why is the surface of Mars so cold? Shouldn't it trap heat and render it hot?
user30617
47
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How can 'HD 140283' be older than the universe?
Scientists have known about the star HD 140283, informally nicknamed the Methuselah star, for more than 100 years, since it cruises across the sky at a relatively rapid clip. The star moves at about 800,000 mph (1.3 million km/h) and travels the…
Mohammad Zain Abbas
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Why is Gaia operating around Earth orbit? Why not send it to Neptune's orbit?
Gaia is an astrometry spacecraft that's currently operating around the Sun-Earth L2 Lagrangian point. Question: why here? Why not the Sun-Neptune L2 Lagrangian point? By orbiting the Sun at a larger distance, it should be able to get more accurate…
Allure
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Does the sun cross other spiral arms in its movement around the galaxy's center?
Today, Ansa.it released an article that states:
[...]. In questo suo peregrinare galattico, il Sole ha attraversato anche
i due bracci della Via Lattea Perseo e Centauro. "Sono zone di alta
densità stellare, in corrispondenza delle quali il…
Patrick Trentin
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Why does the Sun have different day lengths, but not the gas giants?
The Sun's rotation period varies from about 25 days at the equator to about 38 days at the poles. As I understand it, this is because the Sun is not solid, and because of the way centripetal force works, the equator must move faster than the…
Allure
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45
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How does a neutron star collapse into a black hole?
We know the spectacular explosions of supernovae, that when massive enough, form black holes. The explosive emission of both electromagnetic radiation and massive amounts of matter is clearly observable and studied quite thoroughly. If the star was…
SF.
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Shouldn't very very distant objects appear magnified?
My understanding of the expansion of space itself is very shaky,
but if space itself is expanding,
then shouldn't very very distant objects appear magnified?
For example these James Webb Space Telescope (JWST) galaxies from like the year…
orion elenzil
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How do we know that black holes are spinning?
How is it possible to know if a black hole is spinning or not?
If a planet is spinning, you can see it clearly but you can't really see a black hole.
Next thing would be that matter interacts with adjacent matter and we could see in which direction…
sirzento
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How do we have photos of galaxies so far away?
A possible answer for this is that, light emitted from the galaxies travelled a billion miles all the way to earth, where the hubble space telescope picked up this light through its sensors, and was able to construct an image of the galaxy
but if…
K Split X
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How large can a ball of water be without fusion starting?
How large can a ball of water be without fusion starting?
Peculiar question: some explanation might be necessary. My young son is into ‘space’ and astronomy. One of his posters says that Saturn could float, if a sufficiently large ocean could be…
jdaw1
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Why is our solar system "tipped" about 63° with respect to the plane of our galaxy?
Our own solar system is "tipped" by about 63 degrees with respect to the plane of the galaxy. Has it ever been researched or is there any scientific theory which could explain the reason why our solar system and solar systems in general are not…
e-sushi
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In this image taken by Voyager 1, which is closer: the earth or the moon?
NASA reports this photo was taken 19 Sep 1977 by Voyager 1:
It doesn't strike me as obvious how to determine which celestial body is closer to Voyager 1 as the photo was taken. My (not very scientific) guess is that the Earth is closer, since…
Rebecca J. Stones
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Are photons aged?
If a star is at a distance of one lightyear, how old are its photons when they reach earth (from the photons’ perspective)? If time dilation is near zero at light speed, can we assume that the light that we see today from a distant star has the same…
Emir
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Why are we building larger land-based telescopes instead of launching larger ones into space?
This question is a follow-up to Do bigger telescopes equal better results?
How much bigger does a ground-based mirror have to be to match what a space-based one can do? I guess I'm asking primarily for visible light, but I'm interested in general…
GlenPeterson
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Why does gas form a star instead of a black hole?
When a space gas gets pulled together a star is formed. On the other hand, when a massive star dies, it collapses to a black hole.
You would think that the initial mass of the gas would be bigger than the star that had existed for billion years and…
Antons Voitov
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