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1500 questions
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What could be an explanation for a satellite-like moving light in the night sky that dims over time
Last night I saw a bright light moving across the sky. It was probably as bright (or even brighter) than some of the brightest visible stars like Vega and moving quite slowly (so no shooting star) at roughly the speed satellites appear to move. I…
299792458
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Why use a large separate starshade instead of an occulting disk?
The New Worlds Mission proposal has a large occulter on a different spacecraft from the space telescope to block glare from a star to reveal its planets. What is its advantage compared to a disk on an arm such as on the Solar and Heliospheric…
Gnubie
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14
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Identify stars in image from James Webb
This is one of the recent pictures from the James Webb released by NASA. It's a picture of the galaxy cluster SMACS 0723. It locates in the Volans constellation.
I'm trying to identify the stars in this picture. For example, which star does the…
Elon
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How it is not possible to say if Titius–Bode law is a "coincidence" or not?
From Wikipedia:
No solid theoretical explanation underlies the Titius–Bode law – but it is possible that, given a combination of orbital resonance and shortage of degrees of freedom, any stable planetary system has a high probability of satisfying…
d_e
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14
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How bright would the night sky be in the galactic center?
Given that the star density within a parsec of the center of the Milky Way is about 10 million stars per cubic parsec, how bright would the night sky be if you were on a rocky planet within that region?
As this is 10 million stars within a cube with…
Filip Milovanović
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14
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It takes light roughly 8 minutes to travel to Earth from the Sun, but based on which perspective?
The passage of time is relative depending on whether one is the stationary observer or the object/particle traveling at the speed of light (or close to it). I get this, kind of. But, when we talk about "it takes light X [units of time] to travel Y…
Rob Dirnens
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14
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What happened to the reemitted photons during recombination?
To my understanding, the Cosmic Microwave Background Radiation (CMBR) is light released during the recombination epoch where the formation of neutral hydrogen atoms allowed for a sudden drop in the universe's free electron density, hence allowing…
YiFan
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"If earth had rings like Saturn": A few further thoughts on the consequences
I came across this video recently where artists depicted what it would look like if Earth had rings like Saturn. http://www.wimp.com/earthrings/
Please note: The video contains already some information on what I ask here, but I can't assess its…
Patric Hartmann
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14
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Are there large underground caverns on Mars?
Scientists talk about the possibility of life underground on Mars, and I assume they are talking about microscopic life that can live in small gaps in the soil or rock. But is there any evidence that there might be large caverns under the surface…
Kevin Holmes
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14
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How do you propagate asymmetric errors? (on the practical way to...)
I've used uncertainties's ufloatpackage to propagate uncertainties as I thought it's the standard way to do it. Now I want to propagate errors when I have different lower and upper uncertainties.
From this source I understand that
there’s the…
nuwe
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14
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How do Lagrange points L2 and L3 form?
Five Lagrange points form between any two bodies in the space (say Sun and Earth). According to my understanding, Lagrange points L1, L4 and L5 can form because gravitation pull can cancel out here as these are between Sun and Earth (where…
barath
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14
votes
5 answers
Will there be collision between universes?
I just watched one of those videos that shows the scale of the universe, zooming out from one thing all the way out to the sphere that is thought to be the universe. However, they also showed other universes outside our own, and they made it seem…
Margorp13
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Can a satellite stay in one place but not above equator?
I know that there are geostationary satellites that are always seen in one place in the sky and that they all are located in the equatorial area. I wonder if it's possible for a satellite to "hang" still, for example, above Moscow (55.7558° N,…
ALiCe P.
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Milky Way vs Milky Way Galaxy
I saw this question on Quizlet which said:
What is the difference between the Milky Way and the Milky Way Galaxy?
And the answer was:
The Milky Way is a fairly narrow band of faint diffuse light around the celestial sphere. The Milky Way Galaxy…
Jack the Ranger
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Why are fewer stars seen next to the horizon?
I was in the desert the other day, in an area that was free of light pollution.
While it was easy to see the stars above us, I noticed that near the horizon, even when there is no distance light, we can see almost no stars.
Is this normal? What is…
riorio
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