Questions tagged [astronomy]
The science dealing with objects and phenomena located beyond Earth. In particular, this applies to observations and data. At its core, astronomy is the physically informed cataloging and classifying of the contents of the universe in order to better understand what is out there.
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Classical wave explanation for aberration of star light
I am interested in how aberration of star light was explained by wave theorists before the advent of special relativity. The particle explanation is easy (Bradley 1728). I read (mostly AI low level) ...
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Is the length of the day accelerating?
I've been looking into how the length of the day increased due to tidal forces. I saw the following in Wikipedia but am not sure how to make sense of it.
"From the observed change in the moon's ...
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Why does orbital velocity variation correlate with $\sin$ of the angle between position and velocity vectors?
By analyzing the motion of Venus using NASA JPL Horizons ephemeris data (10-year span, 1-hour sampling), I found that the variation of orbital velocity $\Delta v(t)$ appears to closely follow a ...
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Difference between the pear-shaped Earth, ellipsoid, and the geoid
About 32 years ago, when I was a university student, I took a course called Advanced Mechanics that also covered some astronomy topics.
I vaguely remember a derivation showing that the shape of the ...
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Interferometry of gravitational lens images?
The finest feature a telescope can resolve is inversely proportional to its aperture.
Interferometry is used to create telescopes with large (or very large) effective aperture size (although less ...
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Why did prof. H.C. Verma mentioned a "number of black holes exist in space"? [closed]
Direct evidence for black holes such as gravitational wave detections in 2015 or event horizon telescope image in 2019. But in professor H.C. Verma's book which had first edition in 1992.
Many ...
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Can photon be emitted if it will never be absorbed, going to infinity? (in CPT perspective no emission)
Photon in QFT is e.g. a coupling between two electrons using below Feynman diagram - requires both emitter and absorber, they are switched in perspective of CPT symmetry.
So can photon be emitted if ...
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NASA defying physics or what's wrong with Earth flybys [closed]
Imagine a space probe that
starts around Earth at time $t=0$ with velocity $\vec{V_0}$ (sun reference frame) and
goes into an elliptical orbit around the sun such that
after (almost) exactly one year ...
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Are simulations really evidence for the giant-impact hypothesis?
The prevailing explanation for the origin of the Moon is the giant impact hypothesis, which proposes that a Mars-sized protoplanet collided with the early Earth. This impact is thought to have ...
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Are these two studies combined sufficient to conclude the Milky Way’s stellar disk ends at ~35 kpc? [duplicate]
I’m trying to pin down the furthest extent of the Milky Way’s stellar disk using two independent tracers.
I already asked ChatGPT and it converged on the conclusion that the Milky Way’s stellar disk ...
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What is the average refractive index of interstellar space?
Interested in the average refractive index of interstellar medium (inside the Milky Way and at gamma frequencies would be the best).
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Drake equation's validity from a statistical point of view
Drake's equation estimates the number $N$ of active, communicative extraterrestrial civilizations in the Milky Way galaxy according to
$N = R^*\times f_p\times n_e\times f_l\times f_i\times f_c\times ...
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Has the speed of gravitational waves been verified beyond GW-170817?
To my knowledge GW170817 is still the one and only GR+EW signal detected by LIGO. Are there other experimental results confirming that gravitational waves propagate at the speed of light?
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Black hole models with finite-density cores: is a singularity-free solution consistent with GR or its extensions?
In the Schwarzschild and Kerr solutions of general relativity, the mathematical extension to yields a singularity with infinite density and curvature.
Is it mathematically consistent within GR (or ...
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Why is there a scarcity of black holes between $\sim 85\ M_☉$ and $\sim 10^5\,M_☉$?
Observations suggest there is a notable gap in the black hole mass distribution between the most massive stellar black holes ($\approx 85 \ M_☉$) and the smallest supermassive black holes ($\approx 10^...
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