# All Questions

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### Image sets for testing stacking algorithms?

I am looking for sets of astronomical images for testing different kinds of stacking algorithms. The idea is simple: if one has $N$ images of the same object, the signal-to-noise ratio of the ...
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### our sun could be a companion of a big black hole?

Can we track its orbit well now? There is any study that may indicate our sun may be a companion of a big black hole? What is the current constrain about its orbit now? There is a 1000 solar mass ...
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### Glowing ice in ceres

Do ice volcanos glow and maintain a regular shape as in the case of ceres? The 2 volcanoes should eventually merge into one, as they are in a common crater and close together.
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### How to read 5 degree data of green line intensity

When I open the 5 degree data of Green Coronal Emission line from this, I get a weird table which is not simple like the one for Coronal Index. I am only providing the table for 1939. ...
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### How can a supernova affect black hole in a binary system?

Suppose in a binary stars system there is a dying star and a companion black hole as they orbit around each other. My question is what will possibly happen to the black hole if the partner goes ...
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### Could someone see anything while being inside black hole?

If we managed to survive in a black hole and move inside the event horizon then could we see the surroundings of the black hole inside the event horizon by source of light? Can the light not come up ...
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### Determine the moons of Jupiter through a telescope

I was doing my own "space exploration" last night with a telescope. Being a space noob I can't visually determine stars or planets (I know the moon, though), but I focused on one particularly bright ...
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### Would a tablespoon of a neutron star remain intact?

I've heard people say that a tablespoon of neutron star would weigh over a billion tons. If we ever could take a tablespoon of one would it still remain intact with the same density?
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### Statistically speaking, what is the most commonly used operating system by astronomers worldwide? [on hold]

Currently I'm in my third year of university. I would like to work in the field of observational astronomy (not so much theoretical astronomy). In about two weeks I'm going to buy a new laptop ...
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### Moment of falling in Black Hole if it can evaporate

If I understand correctly for outside observator object never cross event horizon. Then if black hole can evaporate this mean object never cross event horizon? How it could be right when for object, ...
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### Did atoms in human body indeed come from stars?

I think I am not alone who saw videos about that we (humans) are made of same atoms which someday were in stars. In other words, some atoms in our bodies are from stars which exploded billions of ...
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### close binaries could have a very eccentric orbit?

For example, binaries with period < 5 day could have a very eccentric orbit? What kind of factors could slow down orbital circulation? Anyone knows some ...
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### How to orient ESO's Milky Way Panorama in a 3D model

I have been trying hard to find the star "Polaris" in the following image from ESO and Serge Brunier: From peering at other maps and simulation apps, I think it should be in the top-left quarter, ...
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### Evolution of the Hubble parameter

In the lambda-CDM model describing an accelerating Universe, the Hubble parameter is currently decreasing with time. Will it continue to decrease forever?
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### Enhanced Star-Gazing with Special Glasses

I watched a video yesterday on how telescopes not only magnify images but also increase the amount of light entering into your eye, allowing you to see things not normally visible with naked eye. ...
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### Astronomy-themed names, wordplay, connotations

I use an astronomy theme for naming my main computer and parts thereof. It started with a machine named Cassini, build while watching the arrival of the exploration mission and Saturn Orbital ...
27 views

### Were magnetic monopoles created before, during or after inflation?

In the case that magnetic monopoles exist, when were they created? I thought that all particles were created after inflation, but I've read some comments recently that hint at a pre-inflationary ...
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### Space time and aging

Would a more significant curvature of spacetime relative to earth (i.e. time on jupiter) effect the aging process? Basically would you age at a slower rate? Or age faster on the moon?
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### Missing Terms in Weinberg's treatment of perturbations on Newtonian Cosmology.

I was reading Appendix F of Steven Weingberg's book "Cosmology". In this Appendix he works out the perturbations to a cosmological fluid described by non-relativistic hydrodynamics and Newtonian ...
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### What are the equations for an orbit with time as parameter?

I am preparing a talk on the Equation of Time, and I want to produce an animation of the movement of the earth around the sun, in an exaggerated ellipse, to illustrate the speeding up and slowing down ...
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### What are the azimuths of the planets' orbits?

I am creating a virtual solar system model and I want it to be as realistic as possible (e.g. orbits are ellipses, not circles, and orbits are oriented correctly, not all coplanar). In order for me ...
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### Given a date obtain latitude and longitude where is the sun zenith

Searching is easy to find terminator line (frontier between day and night) or the position of the sun in the sky given a position on the earth and a time; but I can't find how to obtain where is the ...
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### What decided how the Kepler space telescope was pointed?

I suppose that the Kepler field was well chosen. It is rich in stars and has minimal background light since it is pointing out from the disc. But other things could have been considered. For example, ...
52 views

### How strong does a light source on the Moon have to be to be visible from Earth?

Flashes from some meteoroid impacts on the Moon can be seen with the naked eye. How much light must a future lunar base emit in order to be visible as a dot in the lunar night (like the flag of ...
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### Is there a theory / equation showing whether or not two passing bodies will go into orbit around each other?

I am looking for a theory that shows whether or not two passing celestial bodies will go into orbit. I assume there would have to be a critical point where the gravitational attraction is stronger ...
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### PowerSeeker 114Q

I just purchased a powerseeker 114q by Celestron. This is my very first telescope. I believe I assembled it correctly however I can't see anything out of it. Well I can see a small corner of an image. ...
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### Is the North star going to stay in the North sky?

Considering how the our solar system, and how every other star in the galaxy is traveling through the cosmos, it seems like it's a miracle that the stars and constellations in the sky stay as constant ...
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### How are errors on X-ray photon index propagated to X-ray spectral index?

I have seen that in X-ray astronomy, astronomers often talk in terms of photon index $\Gamma$, which is related to spectral index $\alpha$ by relation $\Gamma$ = $\alpha$ + 1. Are the errors on ...
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### How to tell a nebula from a galaxy?

Not all galaxies are spiral in shape[1][2], some nebulae are huge[3] and nebula are the nursery of stars[4]. How to tell them apart? Note I have already compare the contents for galaxy and a nebula, ...
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### Habitable Planet around Red Dwarf

Is there the possibility for a habitable Planet around a red dwarf? It is not required that the whole surface is habitable, but it shouldn't be a tiny spot. After reading a bit I assume the planet ...
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### Can asteroids contain atmosphere?

Gas is abundance in the universe, can a massive asteroid draws in these gas forming a thin atmosphere?
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### Would a human body float in the dense atmosphere of Venus?

To survive high in the atmosphere of Venus, all you would nead to wear is suit that protects you from the sulfuric acid vapors in the air and a supply of breathable air. Assuming (for simplicity) that ...
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### X-ray flare questions

I search the reference papers about flare, but nobody said something about below clearly. Could anyone give some help? If a single X-ray decay without eclipse or other irrelevant factors is not able ...
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### When the universe expands does it create new space, matter, or something else?

I am wondering what exactly is meant when it is said the universe expands. Does it simply create new space for matter to fill, does it also create new matter/dark matter to fill that space, or am I ...
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### How are boulders formed on asteroids?

For example: Are they soft landed meteorites? Or do they form from melted material during a violent impact? Or are they the result of some kind of erosion process?
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### which or what kind of star has a very stable luminosity?

I mean those kind of stars should be very stable and barely have activity. Their light curves should be very very flat. Our sun, as a G type star, are not so stable. At lest there are lots of ...
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### How can we derive photometric redshift?

Is there any good tool than can derive photometric redshift or good reference paper? We need to assess photometric redshift based on GALEX(Fnu and Nuv), Sloan(ugriz) and 2mass(jhk) magnitudes. Could ...
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### How deep and shaped is the depth of a black hole?

A common representation of a black hole is a black circle which if I'm correct, indicates its breadth. This representation depicts it as a 'plate', so a really small depth compared to its breadth. ...
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### Calculating RA/dec from JPL ephemeris data

I'm using JPL planetary ephemerides to calculate the position of planets. Using DE405 ephemeris (using a parser provided by Project Pluto with all tests passing). I am fetching the position of Mars ...
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### Circular formation around the moon

I have seen a large circular formation of cloud around the full moon sometimes. Have anyone seen the same? What is the reason behind this formation? Due to lunar attraction? Most of the sky is empty ...
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### Is there a general term for epicycles, deferents, and eccentrics in Ptolemaic astronomy?

According to Ptolemy's (c. 150 CE) account of the motions of planets, planets moved in circular paths ("epicycles") around center points that in turn moved around the center of the earth along a path ...
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### Concerning fate of Milky Way Galaxy

Andromeda Galaxy is the largest galaxy in the galaxy cluster[1] called Local Group[2] and our Milky Way Galaxy as well as some satellite/dwarf galaxies are orbiting around each other within Local ...
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### How long for a complete solar system cycle

Considering the solar system as a closed system, how long until all the planets pass twice by the same position relative to each other? I would say that you'd have to get the length of the year in ...
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### What's the difference between grism and grating?

In spectroscopic observations, sometimes you meet grism, sometimes grating. Both of them could cause light dispersion, but what is the difference?
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### SETI and Black Holes [closed]

Given our current knowledge of the physical universe isn't it reasonable to assume that advanced civilizations would eventually chose to migrate toward the black hole in the center of the galaxy they ...
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### How to calculate magnitude of a star in a triple star system?

I want to find a star's magnitude in a triple star. I already knew the the magnitude of the triple star and the other two star, but I don't quit know how to solve it. Is there a way to find it?
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### Is there a legend for these 88 HST images?

Is there a legend for these 88 Hubble Space Telescope images? I have a 6000px x 4800 px version of this image (reduced & rotated to 480x600 here) that I use for an image slide show. I would ...
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### What is the direction of a comet's dust tail before and after perihelion?

I recently created a visualisation of comet ISON's orbit. However, I received a critique that the dust tail of the comet should be pointing away from the Sun after perihelion. As far as I know, the ...