Unanswered Questions
177 questions with no upvoted or accepted answers
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Is there software that will let me calculate things like lunar phases and the position of bodies in the sky in a custom solar system?
I am constructing a fictional solar system and want to be able to calculate astronomical events and locations, like lunar phases and eclipses, plus the positions of other astronomical bodies in the ...
- 131
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Why are CMB peak heights sensitive to the physical densities
A very simple question: why should it be that the CMB power spectrum allows constraints to be placed on the combination of parameters
$$\omega_c = \Omega_c h^2$$
$$\omega_b = \Omega_b h^2$$
as opposed ...
- 61
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Classical Mechanics : Interaction Sun Radiation Pressure - Gravitation
I have a theoretical problem that merges the effects of a gravitational field and the Sun radiation pressure. The problem goes as follows:
A spacecraft orbits the Sun in absence of any other body ...
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Why is dark matter required?
I read somewhere that the galaxy is spinning too fast (in places). Therefore, there must be dark matter. What are the equations that explain how fast the galaxy should be moving, and how are they ...
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Superconducting space dust; what transient fields could induce persistent current loops?
Science Alert's Superconductivity Has Been Discovered in Meteorites For The First Time quotes from Superconductivity found in meteorites (Wampler et al. PNAS March 23, 2020)
The paper describes the ...
CommunityBot
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Information on Planetary nebula formed from the death of our star the 'Sun'!
I want to know the expansion rate, composition, mass and density of hydrogen present of a Planetary nebula similar to that which will be formed after the death of our star the sun.
Knowing these ...
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Combined mass of binary stars
This is Question 17 from USAAAO Practice Round 2015. The answer is D. It would be best if someone can detail out the workings.
In a nearby star system, two stars are seen to orbit each other every
...
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Can "rock stars" form from interstellar dust?
Imagine a large and massive dust cloud made of solid phase micrometeoroids, asteroids and larger planetoids, all material in it is in solid phase, and contains no hydrogen or other volatiles in gas ...
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Does a planet's rotation speed and distance from its star influence the precession of its axis? And is the Earth's precession "normal"?
I guess first off, do all/most planets with a tilted axis experience precession? And if so, is it usually in the same direction (clockwise or anticlockwise)?
What I'm really curious about is if a ...
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Mass of the universe
How do we calculate the mass of the universe taking into consideration dark matter?
Mass of visible matter can be computed by stellar method, but how do we calculate mass of dark matter which we don'...
CommunityBot
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Total number density of galaxies and problematic expression in practise
This post comes from physics exchange forum, I have transfered it here, maybe I will be luckier since I have not received answers on the other forum.
Here is the issue :
I am asked to give the ...
CommunityBot
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How large are the effects of nongravitational forces on comet Halley?
The effects of outgassing on comet orbits can be noticeable. Yeomans, in Cometary orbit determination and nongravitational forces, 2004, wrote:
As the astrometric datasets improve and lengthen and ...
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What is the spectral power output of a typical galaxy?
I'm looking for a function which gives the typical isotropic spectral power of light emitted by an entire galaxy on the whole electromagnetic spectrum (in watts per frequency unit), as a function of ...
- 8,135
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What is meant by ionization states?
I am going through the theory of Saha equation but I am not able to understand the concept of ionisation state? What are ionization states actually?
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Angular momentum in planetary disk formation
Reading about the formation of planetary disks, one of the major problems, it seems like, is the evacuation of angular momentum. Aparently planets can't form with the amount o angular momentum the ...
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