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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Setting correct spin vector components for orbital simulation?

I am trying to write a code that generates the correct planetary spin vector components (x,y,z) for input into an orbital simulation that will start the planet with the correct obliquity and ...
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Why don't stars stop moving? [duplicate]

In my astro class we are learning about red/blue-shifting and I was wondering how to related to stars. So if a star is moving in some direction, the light leaving the direction of motion would be ...
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How to find the position of a star at a certain point during its orbit [closed]

Hey I am trying to find a way to find the position of a Red Dwarf star that is in an elliptical orbit at a certain time during it's orbit. I know the Red Dwarf's semi major axis which is 3 AU (...
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Do enough photons from Proxima b make it to Earth that its surface could be imaged directly with a huge, but not astronomically so, telescope?

I hope I didn't miss someone answering something similar. I was doing a small thought experiment. And I was wondering whether you kind people would check up on my math. Say we want to build a ...
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Parallax angle calculation

I'm trying to understand how the parallax angle is calculated. I alredy read this explanation. So we got that distance between the sun and the star is d = tan(α) * 1 AU. That said my doubt is about ...
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Why precise localization is required for higher frequency radio observation?

I am reading an article about Fast Radio Bursts. Since most of these bursts could not be precisely localized, a majority of them are detected at 1.4 GHz. There it is mentioned that precise ...
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Would Earth always face Sun the same way if Earth didn't rotate around it's axis?

Imagine for a second that Earth no longer rotates around its axis. It still revolves around the Sun. However, would the Earth: face the same way towards the Sun as it goes around it (permanent time ...
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How can these two definitions of the eccentric anomaly give the same answer?

The eccentric anomaly,$E$, is defined via the equation, $$ r = a(1-e \cos E) \tag{1} $$ for radius $r$, semi-major axis $a$ and eccentricity $e$. It is ALSO defined in terms of the Kepler Equation ...
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Angular elevation of the sun [closed]

Can you give mathematical proof of why the angular elevation of the Sun is the same for mostly person at any time? Explanation:- if a father and his son look at the sun , in mathematics we take angle ...
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Could earth's axial tilt shift due to an asteroid hitting the moon? [closed]

Earth's obliquity is around 23,5°, a value that is known to shift over secular timescales (cf. Milankovich cycles). However, I've been wondering if a change of axial tilt could occur rapidly (without ...
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Between Mercury and Venus, which planet produces a longer transit? Assuming both planets describe same path on the solar disk

Is it even possible to give a definite answer to this question? There are a lot of factors involved in this like Earth's position and motion relative to the planets and of course their own motion and ...
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Explain how scaling of the inverse square law breaks down at a stars surface

If the radiation pressure at distance $d>R$ from the center of an isotropic black body star is found to be $$P_{rad}=\large{\frac{4\sigma T^4}{3c}}\left[1-\left(1-\frac{R^2}{d^2}\right)^{\frac{3}{2}...
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Does Olber's paradox imply a bright sky or a divergent one

Doing Olber's paradox with specific systems is simple enough. Take stars on a grid of length $\ell$, then the total luminosity is just \begin{equation} L = \sum_{i,j,k} \frac{L_0}{4\pi\ell^2(i^2+j^2+...
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Does light from source one mil. light years away take more than 1 mil. years to reach us?

Because of the expansion of space itself, did light from a galaxy one million light years away actually take more than one million years to reach us? Also, if we are looking at a galaxy one billion ...
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Discerning binary stars

What is the minimum magnification that one would need to discern a pair of binary stars if viewed from Earth? Are there factors other than magnification that matter? If so, why?
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How are the relative distances of celestial objects from the Earth calculated using observations at a single time instant?

How does one find the distances of celestial objects in the night sky, such as the Moon and the stars, from the Earth using a snapshot of information (including, say, the intensity and wavelength of ...
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What is a simple argument to prove that the stars in the sky are further away from the Earth than the Moon?

How do we know, without using modern equipment, that the stars are further away than the moon in the night sky? Further, is there a simple and actionable argument to prove that this is indeed the case?...
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Is it possible to see the history of space if it expands faster than the speed of light? [duplicate]

I was wondering if it would be possible to see the history of space if one was to stand at the edge of the universe as it expanded faster than the speed of light. If the universe was to be expanding ...
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Have recently discovered objects like SMBHs and exoplanets shed new light on the Fermi paradox? [closed]

The last 30 years has seen the discovery of new astronomical objects, most notable exoplanets and supermassive black holes. Do any of these shed new light on the Fermi Paradox? How?
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Collision or impact of a gamma-ray burst against the magnetic bubbles at Solar System's edge

I'm going to ask* about what should be the effect/interaction, if any, when a gamma-ray burst crashes or hits against the magnetic bubbles at Solar's system edge. These magnetic bubbles are explained ...
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Why do sun light rays that come through clouds not look parallel, despite it being so far? [duplicate]

I was at the airport last friday and there were some nice sun light rays, although not much of a good spot to take a picture. What weirds me out every time I see them is that they look as if coming ...
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If we could only see as far as our galaxy cluster, what and how would we know about anything beyond it?

A silly question that occurred to me while watching one of those "scale of the universe" videos. If our observations were only limited to our galaxy cluster - maybe because the expansion of the ...
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How does LIGO cover the whole sky?

This article says that "[LIGO] is an omnidirectional gravitational-wave detector that monitors the entire sky." But how is that possible with just two flat detectors? If both locations detect a wave ...
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Observational evidences of the early universe other than CMB

CMB is a great experimental evidence that the universe was once in an hot themal phase at early times. Supposing all the CMB observations failed for tecnical reason (for example the rocket shipping ...
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At what point in size does gravity force a celestial body to become “round”? [duplicate]

I am watching a video on asteroid size comparisons and I noticed that 2 Pallas (512 km) and 4 Vesta (525 km) are both "spherical" in shape (pretty much anyway). However 52 Europa (319 km) is also ...
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The Dimming of Betelgeuse

Supergiant star Betelgeuse has been getting dimmer at an unprecedented pace over the past few months, leading some astronomers to wonder if it might be in the process of the collapse that precedes a ...
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Determining Mass:Light Ratios for Galaxies of Known Magnitude and Distance

I’m currently stuck on a method to determine the mass to light (mass to luminosity/intensity) of galaxies with measured magnitude and known distance. I started with (v is apparent magnitude, L is ...
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What causes this “hem of his garment” aurora (or is it fake)?

This picture of a "hem of his garment" aurora in Finland is going the rounds today. Is it real, and if so what causes it to be white instead of the green shades normally associated with aurora. When ...
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How NASA scientists confirmed that the 'Pale Blue Dot', taken from Voyager, is earth? [closed]

It could be Mars or jupiter also? https://www.space.com/pale-blue-dot-earth-space-photo-remastered.html
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If neutrinos were their own antiparticles, would be observe a photon background from $\nu$-$\nu$ annihilations?

If neutrinos were their own antiparticles, would we observe a photon background from neutrino-neutrino annihilations? As neutrinos are so abundant, why don't we observe such a background? Is the ...
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Why do satellite methane detectors use some spectral lines and not others?

I was reviewing absorption/transmittance spectra and was wondering why certain wavelengths are chosen for detectors and not others. Take methane for example For small electronic IR detectors they ...
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Are there any black hole neutron star binary?

Has a black hole-neutron star binary aver been observed? I mean observed in any way: gravitationally, through eclipse, or any other means. EDIT Thanks to the comment to this question, we know that ...
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Measuring $H(z)$ with the Differential Age method

I was reading about how astronomers measure the Hubble parameter without relying on a cosmological model. They use something called the differential age method. They use galaxies in a similar ...
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Does parsecs times arcsec/yr equate to any specific unit?

Basically, I wanted to know if one multiplies proper motion (in arcsec/yr) to a distance (in parsecs), without conveting it to km/s (not multiplying it by 4.74, the conversion rate), does it equate to ...
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Absorption cross section for Nitrogen in the visible spectrum

I am trying to find data for the absorption cross section of Nitrogen at various wavelengths in the visible spectrum (~400-800 nm). I can only find data at lower wavelengths, however. Data from the ...
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Calculating errors based on other variables

I am trying to calculate the mass and respective error of a star in kg. I have the numbers in units of $M_{Sun}$,in the form $M_{star}=(a\pm b)$ $M_{Sun}$. Given that I have the mass (with error) of ...
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How do astronomers identify different elements from the combined emission spectrum of multiple substances?

It is said that the spectral lines of a particular atom or molecule is unique and this could be used to identify the substance by comparing the spectrum with the existing library of spectra of ...
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What are the physics principles behind multiply-lensed quasi-stellar objects (QSO) images?

If a quasar is located behind (in the line of view) a galaxy, its light is bent by the gravity of the galaxy. The light appears as a ring to the observer, see https://www.space.com/14929-quasars-black-...
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Would a parallax measurement of distance to a star be affected by relativistic length contraction?

Let's say you had 2 ships launched 1 light year apart towards a star 10 ly away and they were equidistant from the star moving at .6c towards it. Would their velocity cause their parallax distance ...
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Why couldn’t dark matter be from advanced technologies? [closed]

(Coming from a layman) Why couldn’t dark matter be the consequence of advanced technology? For many reasons I can imagine that the game theory for intelligent life is to eventually hide/ camouflage ...
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Are night and day lengths over a year equal everywhere on earth?

(Question from math.stackexchange, because people told me to better ask here: Original link) As you all know, in winter the nights are longer and there is nearly no sun, but in the summer there are ...
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Lunar surface brightness

If the Moon is visible against a clear blue sky with a lux value of around 30,000 does it stand to reason that the lunar surface must be brighter than that?
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What is spectral redshift resolution of observationally detected damped Lyman Alpha clouds?

What is the spectral resolution, $\Delta z,$ when detecting damped Lyman alpha systems at different epochs, $z \sim 0-3,$ through current and/or future observational instruments? And is this redshift ...
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Shadows cast by Venus

How and why would a shadow on earth cast by Venus differ from one cast by the Sun or Moon? My thinking is that the shadow would be much fainter because less light is being blocked. Also, I think it ...
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On the derivation of the north-south aberration angle

In A.P. French's Special relativity, page $39$, the author said the north-south aberration angle $\alpha$ below, in figure (b), is equal to $v\sin(\theta_{0})/{c}$, where $\theta_{0}$ is the angle ...
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What does. DM- nu, sigma = 10^-33 m_DM GeV^-1 cm^2. mean?

I tried posting a screenshot above...... On Ethan Siegel's blog over at Forbes, he has repeatedly posted a graphic showing possible 'new physics' that could explain why the Planck satellite ...
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A star or a galaxy?

When we look into the beautiful sky in the night, exclaiming how beautiful these shining stars are. My question is how could we tell, whether any of these shining "point" is a star or a galaxy? If ...
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Measuring lowest photon energy

If I wanted to buy a receiver that measures the energy of incoming photons, what is, not theoretically, nowadays the lowest energy that can be measured (in joule)?
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Why is the moon so bright when it is really dark

The moon is bright, and if you were 50 times closer it would be 25 degrees across with the same surface brightness, which would be pretty dazzling. Looking at the moon through a telescope (which ...
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Does the length of days change substantially during the year, from more than 24 hours to less?

I just read an article in the 'Science' journal online about Monarch butterfly migration. (Mysterious monarch migrations may be triggered by the angle of the Sun , by Elizabeth Pennisi , Dec. 18, ...

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