# All Questions

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### Chemical reactions in white dwarf and carbon allotropes

White dwarfs consists mostly of carbon and oxygen. In my opinion, they are too hot to contain these elements in molecular form and hence chemical reactions does not happen (I think resulting CO2 will ...
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### Calculating Orbital Period

I was using this formula to calculate the orbital period of a satellite in days: T = sqrt[(4*pi^2)*R^3/GM-center] Where R^3 is the radius of the orbit, or distance of the semi-major axis, G is ...
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### Why (actually) aren't ground-based observatories using adaptive optics for visible wavelengths?

Adaptive Optics (AO) techniques allow ground based observatories to dramatically improve resolution by actively compensating for the effects of Astronomical Seeing. The atmospheric effects are quite ...
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### Are we made of stars we're seeing?

a fresh astronomy enthusiast here. Recently I've been reading upon how immensely far other stars are from our solar system and how is it possible that we may be seeing stars that are already dead. My ...
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### Is it possible for the Sun and the Moon to crash into each other?

Is it possible for the Sun and the Moon to crash into each other? If yes, under what conditions? If no, why?
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### Can dark matter be explained by a nearby universe? [duplicate]

There is a conjecture in string theory wich says that dark matter is the result of a nearby universe. Suppose we live, to make things imaginable, in a line on a very small cylinder, then on the other ...
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### Calculating orbits for beginners [migrated]

I'm a game developer, and I'm working a space game, where I have to simulate a spacecraft's orbit, traveling from the earth to the moon. I would need the apoasis and periapsis of the orbit. I have the ...
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### Was NASA's moon mission completely fake? [on hold]

I really want to know whether NASA's Moon mission really was a hoax, or if it is a fact. Since there are many points and scenarios which proves it as being filmed in a film studio with controlled ...
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### Why weren't the Hubble light-echo images of V838 Monoerotis supplemented by ground telescopes?

Drawing from this answer The V838 Monocerotis expansion (not a supernova) and the observation of the subsequent "spectacular" light echo was quite a notable event! From Nature 422, 405-408 (27 ...
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### Does a self-gravitating gas necessarily develop turbulence?

Though we may still doubt the exact driving mechanism of turbulence in each particular case (ISM, MC, circum-BH/-stellar discs, atmospheres...), can I say that in a sphere of dark matter particles no ...
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### Solar Elevation Angles — Anomaly?

"The solar elevation angle is the altitude of the sun, the angle between the horizon and the centre of the sun's disc." - Wikipedia The meridian is when the sun is directly facing earth and is at ...
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### conditions of the early universe and inflation [duplicate]

According to our current understandings (The Inflation Theory) when the universe initially expanded it pushed space and time outward from a point. So if anything was present in the space at that ...
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### When was the nearest star discovered? [on hold]

When historically did we realize that the Sun is a star, like all the others? An answer was posted, then the question was put on hold. I would like to answer: If indeed someone asserted that the Sun ...
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### Why Free-Free emission is regarded as Thermal emission?

I read that thermal emission/radiation are the ones whose spectra is similar to that of a Black body radiation. Also thermal radiation depends solely on the temperature of the object. How can we ...
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### How to calculate the pixel size and beam size of an image?

I have an image with some sources in it. I need to get the pixel size and beam size of that image. How can I calculate it?
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### Which frequency should be used to communicate with a cube satellite?

I am trying to build a cube satellite using a raspberry Pi. I am trying to figure out which radio frequency could be used to communicate with the cube sat to transfer data like images, videos, ...
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### Why did time progress past the singularity?

I hope this doesn't sound stupid but I've always wondered: Why didn't time stop with the singularity before the big bang? I might be mistaken but doesn't time slow in proportion to the distortion of ...
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### What is the first recorded reference to the Moon being a satellite of the Earth?

I saw a list recently of the moons of the various planets and the discoverer(s) and date of discovery. Earth's Moon was listed as Unknown. I know you don't 'discover' a huge disc in the sky. But ...
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### Why do post main sequence stars enter the red giants branch?

I am an early graduate student in astronomy and have hard time understanding why do post-MS stars move up the RGB. Here is what I understand about post main sequence evolution of stars. As their ...
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### Why can't neutron stars ignite and explode?

Beyond the Chandrasekhar limit, white dwarves become extremely hot. As a result, previously unfusable carbon can become fusable, causing nuclear reactions. This leads to thermal runaway and ultimately ...
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### How to calculate the LST of an astronomical object at a given height above the horizon [in degrees]?

My situation: I want to observe M52 at RA = 23h24m48s, DEC = +61deg35arcmin36arcsec from, let's say, Calar Alto at 37.23deg N and 2.546deg W. How can I calculate the Local Sidereal Time (LST) at ...
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I am currently self teaching myself some basic astronomy. My book claims, if a constellation is observed for exactly 6 months during a year, then it lies on the celestial equator. I have failed to ...
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### How to interpret extreme ultraviolet/ x-ray data in the literature?

I am interested in a sun-like star 138 light years away that is in the EUVE catalog. A table shows that a photon count of 2.6+/-0.5 photons per kilosecond at 100 angstroms has been detected for this ...
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### Why dust is optically thin in Far Infrared wavelengths?

What is the actual meaning of the statement 'Dust is optically thin in the Far Infrared (FIR) over most of the Galaxy'? Kindly Help
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### Does the sun now 'bypass" some of the original zodiac constellations?

This question got me thinking of an interview of, or a talk by Neil deGrasse Tyson that I saw somewhere in the YouTube universe, giving a question one might ask to possibly challenge literal ...
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### Binary Star question [duplicate]

Is it POSSIBLE that we are a binary system? I have been doing research into this topic and it seems we may infact be a binary system. If we are, what effects would a massive body comming into our ...
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### Why does the Chandrasekhar limit affect white dwarfs differently?

The Chandrasekhar limit is the maximum mass of a stable white dwarf star. Beyond this, a carbon-oxygen white dwarf will typically explode in a type 1a supernova, due to the nuclear reactions at those ...
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### Is a wormhole makeable? [on hold]

In sf movies, a wormhole is easy to make.Wich is to say that an explanation how to make it is easy given and easily understandable. Take a piece of paper, representing 2d-space, make the two ends of ...
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### Is a wormhole asymmetric?

Can objects transverse a wormhole in both directions. A wormhole (Einstein–Rosen bridge), as pictured by the rubbersheet model, appears symmetric. Matter is able to travel in both directions through ...
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### What would the night sky look like if the Milky Way were the only galaxy in the universe?

I'm curious to know what the sky would look like without any other galaxies out there. How much do other galaxies factor into the stars we see? Does the Milky Way account for most of them? Would the ...
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### What does this information about “upper limit column densities” and “upper limit relative abundances” mean?

I was reading the abstract of a paper regarding attempts at detection of a molecular precursor to the amino acid glycine, and I came across concepts (and notation) that I found confusing. If someone ...
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### Birthday of the Universe

With every improvement of measurement we are able to determine the age of the Universe more exactly. I just wondered how much and what means it would need to narrow the range of age so that it would ...
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### $\Lambda$CDM model or the BB model? [on hold]

The Lambda CDM model is the parameterization of the Big Bang model, it is also called the consensus model of cosmology in many textbooks and websites. Doesn't parameterization makes the LCDM a ...
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### Could gravity be the 4th dimension? [closed]

According to Michio Kaku, in his book Hyperspace, he said that in this Hyperspace, there exist a total of 10 dimensions that govern the laws of physics. Is it possible that we too live in a ...
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### Does earth have retrograde motion?

I am a beginner. Please let me know whether earth has retrograde motion If it does not, let me know the reason
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### Magnification of a telescope

I took an image of Jupiter through my 8" Dobsonian Telescope, attaching a DSLR and a 1.25" Barlow Lens where the eyepiece goes, as shown in this video: https://www.youtube.com/watch?v=reFxoF3XoaU ...
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### $\Lambda$CDM Model and the early stages of the Universe

We know that the radiation dominant era lasted for 50,000 years, how? What equations give us the result of 50,000 years and how are we certain that we are talking about radiation dominant era, same ...
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### Are larger stars rounder?

The Earth is a very smooth sphere, and the Sun even more so, with only minor fluctuations. I am wondering: are larger stars even rounder? Intuitively, that seems self evident, but I am not so sure. ...
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### Why do meteorites explode?

Some meteorites just blaze away, streaking through the sky. This is clearly explained, as they either slow down enough for the flame to cease, or ablate in their entirety, turning to vapor. But some, ...
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### How much competition there is for jobs in astronomy compared to other fields of science?

I will soon finish a master's degree in computer science. I have been interested in astronomy for some time, which has included playing around with a Newtonian reflector telescope and reading about ...
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### Polar satellites for Global Navigation Systems

Why do we need 7 polar satellites for a navigation system like the Indian Regional Navigation Satellite System (IRNSS)?
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### Plot an AltAz grid over a square grid of RADec points

first post here. As I'm new, StackExchange won't let create or use the wcsaxes tag. wcsaxes looks like the most appropriate tool for the job, but astropy is closely related. I think the title says ...
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### The Blackhole “Creator of Stars” [closed]

I have thought for some time on how Blackholes and Neutron stars behave and interact in the nature of space, Now I know we have made some theory's and are still in the process of observation, we ...
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### Stellar mass limits for Neutron Star and Black Holes

Don't hate on me if I am asking a very basic and straightforward thing. I have a few questions about black holes and neutron stars. What is the mass range (in terms of solar masses) for a main ...
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### How much time does the ISS take to repeat its orbit?

I used to go to my roof to see the ISS, but it is not always visible. Then it appears again but does it appear with the exact same orbit as I saw before? Thanks!
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### Is there Kuiper belt/Oort cloud like structure in gas giants?

I know gas giants have moons, just like star have planets, how about kuiper belts or Oort Cloud? Is there any corresponding structure in gas giants? If not, why don't they have?
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### What does the Sun's orbit within the Solar System look like?

Everything in the Solar System revolves around the "barycenter": the overall center of mass. This barycenter is not in the center of the Sun. Some articles and essays I've read go so far as to suggest ...
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### Pinhole Projector: Can I use a specific solar optical eye piece to focus the Transit of Mercury?

The title pretty much explains this one. Can I use a specific solar optical eye piece, or other optical device, in conjunction with the pinhole projector method to focus the Transit of Mercury? ...
Say we have a relativistic fluid/gas, as we have in some astrophyical systems. Now let us write: $e$ - energy density in the fluid's rest frame. $P$ - pressure in the fluid's rest frame. $n$ - ...