# All Questions

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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 percent of planets are in the position that they could be viewed edge-on from Earth? (and thus able to undergo transits)

Star number 12644769 from the Kepler Input Catalog was identified as an eclipsing binary with a 41-day period, from the detection of its mutual eclipses (9). Eclipses occur because the orbital ...
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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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### How would we detect an Earth doppelganger planet?

With our current technology, or technology available in the near future (up to 2025), how would we detect a planet exactly like our own, and how close would it have to be to be detectable? Which ...
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### Quantum entanglement; How many entangled particles can we find in the wild?

If not all particles are entangled in the universe, where there any entangle particles after the big bang; if so how many entangled particles are thought to occur naturally? (I am curious if a ...
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### On a log-log plot of surface gravity to planet mass, what is the meaning of the y-intercept?

I am playing around with data from exoplanets.org, and decided I was interested in the plot of surface gravity to planet mass. I reproduced this plot with Python after downloading their data and ...
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### Can close binaries have a very eccentric orbit?

For example, are there binaries with an orbital period < 5 day and that are very eccentric? What kind of factors could slow down orbital circularisation? Are ...
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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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### What is the most populated/numerous stellar system in which the orbits of all objects are known?

I posed a question or two on here a couple months or so ago about the orbital patterns of each of the seven stars in the two septenary star systems Nu Scorpii and AR Cassiopeiae. They remain ...
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### Telescope Problems

I currently own a telescope, I'm an amateur astronomer and currently just trying to view the moon. I own the Celestron PowerSeeker 70AZ. Link for information on the telescope: ...
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### Cosmological deflation?

Wikipedia tells us: In physical cosmology, cosmic inflation, cosmological inflation, or just inflation is the exponential expansion of space in the early universe. The inflationary epoch lasted ...
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### Why does the Solar System have no (natural) satellites of satellites?

What are the conditions for a planetary moon to have a satellite of its own? How far do the Solar System's bodies fall from the necessary threshold?
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### How can I find out which known stars lie within or close to M8

I'm looking for a way to find stars within a certain region of space, the Lagoona Nebula in this case, based on what we currently know. Are there some databases that allow you to make such queries? ...
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### How to calculate position of an unknown star knowing positions of some other stars from an image?

Suppose I know the coordinates (right ascension and declination) of the stars marked with red. How should I calculate the coordinates of an unknown star, marked with yellow? Searching over the web, ...
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### Is there evidence that what resulted from the Big Bang is “everything”?

Asked this question in the physics forum before I realized there was this one: Do we have any observed evidence that the "known" universe truly is everything that is out there? (I mean everything ...
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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 is the largest object on which the Yarkovsky effect has been observed?

The Yarkovsky effect is responsible for changes in the rotation and orbit of some celestial bodies, most notably asteroids. It has been measured on asteroids, such as 6489 Golevka and 1999 RQ36. What ...
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### Free source of printable star charts in the format of the Millennium Star Atlas?

I've been looking for sources of printable electronic star charts - there seem to be many different ones available, either as part of planetarium software or just plain charting packages. But there's ...
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### Faster than light [on hold]

Before explaining my view about light speed I must sorry at the beginning for my English, and lack of astrophysics background, I am just programmer. It is important, to be conversant with material in ...
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### What is the mass of plasma? [on hold]

I need to find the mass of plasma of the sun corona for may astronomy problem, but when I Google it, it didn't find it. what is the mass of plasma?
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### Nebula and galaxies using 70mm scope

Telescope: Orion 09843 SpaceProbe 3,3 inch aperture(76mm), 700mm focal length, eyepieces - 25mm and 10mm focal lengths. Please tell me whether it is possible to see nebula and galaxies.
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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 dark energy save the earth for a while as the sun heats up?

Would the expansion of space (e.g. dark energy) move the earth further away from the sun over time, possibly saving us for perhaps a few billion years as the sun heats up? Scientists now tend to ...
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### Smallest lunar probe that can be made using today's technology [migrated]

Suppose we want to do a lunar sample return mission. We can then launch a small rocket from the ISS that carries a small probe to the Moon. It will collect a sample and then return to the ISS. ...
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### Likelihood of a stable system with a dwarf planet's orbit inside that of a gas giant

I keep thinking of various planetary system configurations, and would like to know: What are the fundamental references based on Monte Carlo long-term simulation of planetary systems' evolution that ...
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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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### Star versus Black Hole

I'm making a simplified animation for college project on how a star reacts with a black hole. I had known that a black hole sucks in everything and thus should be doing the same for stars. But upon my ...
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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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### Moment of falling in Black Hole if it can evaporate [duplicate]

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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### Retrograde motion and Kuiper Belt Objects

As seen from Earth, planets such as Mars and Jupiter exhibit retrograde motion when they are near opposition (from Earth). I am wondering how this effect extends to very distant objects, such as ...
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### Could our Sun be a companion star of a massive 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 [on hold]

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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### 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? [closed]

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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### 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 ...
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### 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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### 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, ...
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### 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 ...
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 ...