# 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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### 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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### 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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### 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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### 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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### 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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### K-Pg asteroid impact

Is it possible to determine what daytime the Chicxulub impactor striked the Earth 66 mya? Was it day or night, what was the current phase of the Moon etc.? Can sediments, rhytmites or something else ...
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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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### 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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### V838 Monocerotis “light-echo” images morphed into nice video, but why so few original images?

This NYTimes video shows what I think is a series of real Hubble images which have been "morphed" artistically to appear to be continuously expanding. (also see The V838 Monocerotis Star Still Has ...
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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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### Is starquake unique to neutron star?

I read from somewhere that astronomer use X-ray to observe the "shaking" not to be confused with wobbling of a distant neutron star, I think it is similar to what geologist using microphone to ...
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### Does mass create space?

Imagine two cubes each with the side 1 light year. One of the cubes is empty of any matter. The other cube contains a massive star. Does the cube which contains the massive star have a larger volume ...
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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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### 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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### What is the difference between asteroids, comets and meteors?

Some celestial objects seem to be referred to as asteroids, some as comets, and some as meteors or meteorites. What is the distinction between all of these different objects? Are any of them the ...
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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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### Simple Question about Constellation

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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### 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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### Could we verify the structure of a black hole by observing an orbiting object?

Can we determine the physical structure of a black hole by observing its gravitational effect on objects in orbit? There are three possibilities that I see, and would like to test: Singularity at ...
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### How could we tell if the Universe is infinite? [duplicate]

I've heard from a number of people that the Universe is infinite, and from my perspective, I can't see how this can actually be known, especially given that the Universe started out a finite size and ...
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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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### 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 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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### 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 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 long would it take to reach the edge of the reachable universe?

How long would it take to reach the current edge of the reachable portion of the universe, with the following bounds in mind: We figure out a way build a space ship to provide a constant 1 G ...
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### How/where to check where the Sun is (constellation)?

I would like to check in which constellation the Sun was in at some time in the past, any recommendations how to do that?
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### Is the influence of gravity instantaneous?

When I was in college, I posed to my astronomy professor a thought experiment that had been puzzling my mind for some time: "If the all matter in the Sun magically disappeared, instantly, how long ...
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### What happens to the information on the event horizons of two merging black holes?

What happens to the hairiness/information on the horizons of two black holes if they collide? After Hawkin the information of the matter which has fallen into the blackhole is encoded on the surface ...
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### Can we calculate the average temperature of the heliosphere?

It is my understanding that one can measure the temperature of the universe by measuring cosmic microwave background radiation. Could we also use this method for calculating the average temperature of ...
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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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### During night on the Moon is there Earth light and Earth phases?

I realise that night time on the Moon is two weeks, however I am curious if during the night there, whether or not the Earth reflects light in similar manner to the Moon. On the one hand, I know it ...
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### How do I see more than just points in the sky?

I just bought a new telescope with these specifications: Aperture: 203 mm Focal Length: 1200 mm F/ratio: f/5.9 I usually use a 28 mm eyepiece, giving me about 42.5x magnification, but I also have ...
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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 ...