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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How much energy does a cosmic ray lose before it hits a detector?

The origin of extremely high energy cosmic rays is still unclear, by my understanding. But say that they are produced by whatever local source does it: how much energy is lost to environmental effects ...
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Find location of geo satellite [closed]

I have some satellite antenna which is installed with offset. In order to verify the offset calibration to the right direction on first installation, I'd like to instruct to the antenna the satellite ...
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Why are radio telescopes in orbit radio telescopes?

We use radio telescopes on Earth because of the atmosphere, right? It blocks the more energetic wavelengths but not radio waves and microwaves. So, since radiation like x-ray and gamma radiation are ...
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About the non-intuitive announcement at 12 May 2022 of the EHT team that spin axis of Sgr A* Black Hole facing Earth?

What is this all about?: At 12 May 2022 at the ESO official announcement live streaming event the EHT representatives claimed that the Sgr A* BH accretion disc spin axis is sort of facing Earth's ...
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What are the three bright spots in the Sagittarius A black hole picture? [duplicate]

Today the first picture of the Sagittarius A black hole was released. Although somewhat similar to the first picture of the M87 black hole released three years ago, to my eye there's a notable ...
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The Event Horizon Telescope collaboration will announce groundbreaking observations of our galaxy at 12 May 2022, what this announcement could be? [closed]

"Live webcasting for the ESO-hosted EHT 2022 event On 12 May 2022 at 15:00 CEST, the European Southern Observatory (ESO) will host a press conference on groundbreaking new Milky Way results from ...
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How can we extract the Doppler shift of supernovae?

My understanding is that supernovae are used as standard candles, whose spectral lines indicate the recession velocity of the host galaxy. But the material from the supernova is ejected at a ...
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Wouldn't our own EM emissions be good the places to look for signs of intelligent life?

I read that only a narrow band of radio waves are reserved for astronomical observation, and humans emit all sorts of electromagnetic waves, which leads to my question: Could there be signals of ...
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Why is it that Transneptunian Objects (TNOs) have colour indices that are in the red yet some are considered blue, gray, or neutral?

The B-V (Blue-Visual) colour index for Orcus is .64, for Eris is .78, for Makemake is .83, for Quaoar is .94. This is all in +, which indicates red and cold, as in red stars, and - indicates blue, as ...
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Based on structure formation and the lifetime of the universe why is there an upper bound on the cosmological constant?

I understand that significantly greater values than the cosmological constant would result in difficulty for the formation of large gravitationally bound structures within the lifetime of the universe....
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How does one generate a formula(s) for an artificial satellite's location at time $t$ given a set of known locations at discrete times?

Given a set of spatio-temporal points in space {(Lat_1, Lon_1, Alt_1, Time_1), ... (Lat_n, Lon_n, Alt_n, Time_n)}, I need a function (i.e. a formula) that takes these points (or subset of points) as ...
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Continuity equation for the estimation of cosmological dimensionless parameters

I want to set up a system of equations to find the dimensionless density parameters $\Omega_i$ as a function of $N=\ln(a)$, from the continuity equation: $$\dot{\rho_i}+3H(p_i+\rho_i)=0$$ where the ...
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Would the collision of a neutron star and an anti-neutron star destroy the galaxy it happens in?

My question is a follow up to this one: Does the collision of a neutron and anti-neutron produce energy?. Quoting from the accepted answer: "The collision of a neutron and antineutron star would ...
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Could I, within my lifetime, reach any star I wanted if I went fast enough?

Disclamer: I'm not talking about FTL travel here. I'm also not talking about any weird space warping mechanics like wormholes and such. I've always thought that if a star was 4 light years away, then ...
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Collision-Induced Spectroscopy

In spectroscopy, are Collision-Induced Absorption and Collisional Excitation the same thing? If not, how are the effects they have on the spectra related?
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Image Processing of Gravitational Lensing

I'm trying to find information about a type of astromony experiment/analysis. I'm not really sure what the name of what I'm looking for is, but I'm trying to simulate a black hole with gravitational ...
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Airy's Water Filled Telescope: help required to fully understand the calibration procedure followed

I am trying to understand Airy's Water Filled Telescope and the calibration procedure used (Airy, G. B., "History and Description of the Water Telescope of the Royal Observatory, Greenwich", ...
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Distance to source of GW 150914

Looking at the original paper on this gravitational wave, PRL 116, 06112 (2016), it is difficult to determine how they estimated the distance to the source. Can anyone provide some explanation? They ...
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Are we totally limited to Milky Way galaxy for all star science?

Simply put; Are we able to make any observations of the individual stars in other galaxies? Is the depth of our scientific knowledge on star systems, are all based solely on stars in Milky Way Galaxy ...
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On the Critical Angular Velocity of Stars

I read on Wikipedia that if the Angular Velocity of a star is above its Critical Angular Velocity, it reaches hydrostatic equilibrium in the shape of a Jacobi Ellipsoid. But how exactly would I find ...
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Total brightness from emission spectra?

Some background: I'm looking to analyze stars through a telescope; I'd like get both the visual spectrum and the brightness of each target. I'd also like to have to build/carry as few instruments as I ...
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Large Scale Structure: Math proof that power spectrum being zero at a scale means fluctuations have variance of underlying Gaussian field

(Please don't close this one as a homework question. I am self taught and I have no way to get this information from any other source besides asking it here.) I am trying to solve this question (11.6) ...
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So what do we really see in the image of the black hole?

I have already read this question - Orange ring in a black hole image And also have seen several videos about it (Specificaly one from Veritasium -https://www.youtube.com/watch?v=zUyH3XhpLTo&...
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Why do we see only the sun as yellowish or orangish? Why not stars, because both of their light undergoes atmospheric refraction? [duplicate]

We see the colour of the sun as yellow to orangish on an average due to its light getting refracted due to the atmosphere. Then why do we see stars as white and not colourful, because light coming ...
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1 vote
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Determine Mass of a Star Using Electromagnetic Spectra

How do astronomers determine the mass of a star using spectra. In this answer here https://physics.stackexchange.com/a/503515, they state that the mass of a star is extracted from its spectrum and ...
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Building orientation - how come both summer and winter solstice used for a facade?

I am planning to build a shed atop my terrace. I was analyzing the sun path to determine the overhang length, facade height etc, but got stuck with a conflict as below. The summer sun's location peaks ...
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1 vote
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Source spectral index

Whilst studying the propagation of cosmic rays (CRs) through our galaxy, I was comparing simulated data to data measured by the Alpha Magnetic Spectrometer 02. I am studying the proton flux within CRs ...
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Is the transit technique for exoplanet detections part of the "Wide-Field Precision Photometry Revolution"?

In a exoplanet focused lecture I was informed that the two main techniques for the detection of exoplanets were: radial velocity (VR) and transit. These were very briefly explained to us. When ...
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How do astronomers calculate the mass of celestial bodies light year from Earth?

I have read in many scientific stuff that mass of this planet or that stars is about '$n$' times the mass of Sun. I have gone through many websites and videos on YouTube but didn't find the right ...
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Finding quasars in data

i really hope that’s the right place for this kind of questions, if not, please excuse my ignorance. I am thinking about a way to find some objects in a spectrum, I can simulate combined spectrum data....
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Earth's rotation axis orientation in space in relation to vernal equinox point

Lately I got confused about how the Earth's rotational axis is oriented during the vernal equinox, as I got information that Earth has an equator ascending node equal to about 11°. If, this day, we ...
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Do we see the fluctuations of the CMBR slowed down by a factor of 1100?

Do we see the fluctuations of the CMBR slowed down by a factor of 1100? If redshift streches the signal like a spring it should last longer in our eyes and by a factor of 1100 so every change in the '...
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2 votes
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How does the James Webb Space Telescope avoid stick/slip and creep problems when positioning its mirrors?

The JWST is now positioning its mirrors so they form a single image. How James Webb's Mirrors MUST Work To do this, each mirror must be positioned in 8 nanometer steps in 6 degrees of freedom. Here is ...
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Are there Wolter telescope lenses for consumer cameras?

Wolter telescopes are used for x-ray astronomy. However, I see no reason why they couldn't be used for visible light as well. How would a visible image look when taken through a Wolter telescope? Are ...
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4 votes
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Drawing night sky of planets other than Earth (invariable plane ambiguity)

I'm writing an application that draws maps of night sky that can be visible from other planets (ultimately they are to be exoplanets). Mostly I do it out of curiosity :). I's thinking a lot where I ...
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Are the blur pictures of black hole a proof of Heisenberg's uncertainity principle?

I wonder that are the blur pictures of black holes due to Heisenberg's Uncertainty principle because the velocity of black holes is unpredictable that's why we couldn't take better pictures of them?
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Evaluating an expression for peculiar acceleration

I am trying to obtain this graph from this expression but somehow I cannot obtain it. In the same article it is given that $$r_s = r_v/c$$ $$r = R_c\theta / cos(\beta)$$ and $$C = (\log(1+c)-\frac{c}...
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How is that possible to isolate one particular star light from the others?

We can analyze distant stars by investigating the spectrum of their light. But we have billions of stars in the sky, and I wonder how it is possible to isolate the light of one particular star from ...
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How many pixels could an image of Proxima b taken by James Webb have?

I know it's very difficult for the James Webb to image Proxima b without a coronograph (I have been told by NASA scientists that they don't know yet whether they will be able to do so), but I wonder ...
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How do you combine the expansion rates of two galaxies moving away from each other?

How do you combine the expansion rates of two galaxies moving away from each other? According to special relativity, you use the addition formula to sum the velocities of two particles moving through ...
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If the redshift of CMBR is 1100 is then possible find an object as a protogalaxy at e.g. redshift 100?

If the redshift of CMBR is 1100 is then possible find an object as a protogalaxy at e.g. redshift 100? If the telescope 'James Webb' can 'look' very far should it detect some very distant objects ...
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In what type of trajectory do the Magellanic clouds move through our galaxy?

In what type of trajectory do the Magellanic clouds move through our galaxy? Can be estimated is it a elliptical, parabolic or hyperbolic trajectory? Although it may be a problem due to dark matter ...
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1 vote
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When we measure our distance from a very distant astrophysical object image do we input its past location and our present location?

When we measure our distance from a very distant astrophysical object do we input its past location and our present location? Please take a look on the picture where our past location is A1 and the ...
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How much can we enlarge the picture of a distant galaxy by this method?

If reflection is used instead of refraction and if the curved mirror is highly reflective and cast the image of the galaxy in a obscure chember on a relatively distant screen how much the image can be ...
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1 vote
1 answer
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Confusion with light year distance and space events

I had read that the Betelguese star may be going supernova in may of 2022. Now it is about 500 Light years away, so if we see a supernova explosion in may, then does that mean it occurred about 500 ...
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22 votes
5 answers
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When we say 'Andromeda galaxy is 2 500 000 light years away from us' do we mean 'now' or in a far past?

When we say 'Andromeda galaxy is 2 500 000 light years away from us do we mean 'now' or in a far past and can this past be calculated easily?
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The physical materials (elements and compounds) of the JWST

How many different periodic table elements and compounds are used in the JWST, and where are they used in the telescope? My current list is the following, but I am surely missing many others. Can you ...
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How would I see if there is a transit in this light curve?

I am trying to detect if some binary star systems have exoplanets orbiting them. I've been completing this project for many weeks now, and have managed to write some code that will plot light curves ...
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2 votes
2 answers
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Will the spacing between the mirror segments of the Webb space telescope degrade the sharpness of its images?

I've noticed that the existing spacing between the 18 mirror segments of the Webb space telescope are many times the operational infrared spectrum wavelengths (i.e. 0.6-28μm) of the telescope meaning ...
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Is there any English Translation of Kepler's Works?

Is there any English Translation of Johannes Kepler's Works? I just have "Harmonies of the World". I'm looking for "New Astronomy and Epitome of Copernican Astronomy".

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