# All Questions

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### How would light from a blue or red star affect the way we see?

How would things look if we saw them through the light of a blue or red star? Would there be any changes?
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### If we lived in a multiverse, what would our universe most likely then be named? [closed]

For instance, we live in the Milky Way Galaxy. We don't just call it "The Galaxy", because we know there are multiple different galaxies. So if we lived in a multiverse, it wouldn't make much sense to ...
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### Can the supernova remnant SN 1572 be observed by amateur astronomers?

The SN 1572 remnant, also called Tycho's supernova remnant, is beautiful in X-ray images. It seems to be rather dim in visible light. Are there any amateur photographs of this object? How long are the ...
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### Is the light we see from stars extremely old?

Our nearest star Proxima Centauri is 4.243 light years away from Earth. Does that mean we are seeing light that is 4.243 years old everyday?
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### Are we moving ever closer to the center of our Galaxy due to a super massive black hole?

I've seen in documentaries that at the center of each galaxy is a super massive black hole which holds the galaxy together. Since black holes have such a strong pull, are we slowly being pulled in ...
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### Black Hole, Object or Portal? [on hold]

Some say that a black hole is a rip in space-time, a portal linking two points in the universe as one. How sound is this? I've read that when a giant star collapses, what is left behind (a massive ...
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### Do solar systems have to evolve in a galaxy?

Is it possible for a solar system like ours to exist and evolve apart from all other star systems and galaxies. Sort of like a stand alone solar system or rogue solar system for lack of a better name. ...
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### Can looking at the sun through solar viewing eclipse shades everyday harm your eyes?

I have a pair of Solar Viewing Eclipse Shades that say "Safe for Direct Solar Viewing" and would like to know if my eyes would be harmed if I looked at the sun everyday for about a minute wearing ...
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### Why does the darkening of the Moon go from left-to-right during an eclipse?

In anticipation of the upcoming April 2014 lunar eclipse, I decided to use the 3D virtual planetarium software Stellarium to simulate what it is supposed look like where I live, since I've never ...
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### What happens to the shrinking universe in the presence of the pressure of Hawking radiation?

Black holes release Hawking radiation. Now assume that the universe after all collapses back again, bringing all matter to a single black hole. I assume that this would bend the whole space-time of ...
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### If Venus and Mars changed places, would we then have 3 habitable planets?

This is the supposition: Venus is too hot, Mars is too cold. If they switched places then Solar energy would change to make both more Earth like. We might as well have had three instead of just one ...
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### Heavy bombardment - Why has things cooled?

I was always taught and lead to believe that at the beginning of our solar system, there was a period of heavy bombardment, which is conceivable. Why has it just stopped and we are at peace from ...
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### Is light bending around my finger? [closed]

I was hoping that astronomy enthusiasts/scientists would help me out with a simple question about light. Hold your outstretched hand up to any bright light source (the sun, or even a light bulb) so ...
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### Would Venus have any significant effects on Earth if its orbit were entirely within the habitable zone?

If Venus was entirely inside the habitable zone, or life zone, would its proximity to the Earth provoke any remarkable changes to the Earth?
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### Where is all the antimatter?

The universe supposedly started off with equal parts matter and antimatter and they are said to annihilate each other. Also, nature is famous for it's balance between everything. So all we see is ...
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### Absolute magnitudes of stars

Where to find comprehensive list of absolute magnitudes for stars of different spectral types? I need published paper or web page with data and reference to the source.
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### What would the sky have looked like when galaxies first started to form?

If I stood on a theoretical earth at the time that galaxies were just starting to form, what would the sky have looked like? Due to the smaller size of the universe would it have been densely packed ...
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### Are many exoplanets synchronously tidally locked like Mercury?

The only tidally locked planet in the Solar system i Mercury. But it is synchronously tidally locked 3:2, because of the relatively high eccentricity of its orbit, so doesn't turn the same side ...
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### Why is the speed of light 299,792,458 meters/sec?

Ok, I am majoring in physics (4th year) and I never understood this fundamental (kinda) question. Maybe I haven't explored it enough. For example, why does it take 8min20sec for the light from the ...
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### What is that void that the universe is growing into? [duplicate]

We understand that this is the universe and it is essentially full of space and time, but what is on the outside of the universe, and isn't that nothing, something, and how far does that reach. I.e. ...
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### Formulas to determine the illuminated phase and orientation of the Moon

The phase of the Moon (the bright limb) looks different depending on where on Earth the observer is located and the time of the observation. I've located this video and the accompanying spreadsheet ...
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### Is everything quantum entangled?

So, I am learning about quantum entanglement in my quantum course and had a thought. If the Big Bang is the creation of everything - time included, and this came from a single "source". Would it not ...
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### Why doesn't the earth's surface collapse onto itself? [closed]

From what I know the sun (or any other star) nuclear fission keeps it from collapsing under its own gravity until the fuel runs out, if that's so why doesn't the earth surface like the tectonic plates ...
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### What method is used to calculate the 'quality' of a solar/planetary image?

What sort of algorithm is used to calculate the relative quality of an image, such as is performed by PIPP, Registax, or Avistack? Such applications take planetary or solar images and prior to ...
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### Location on (or in) the celestial sphere

First off, I apologize if I am breaking any site-etiquitte. Secondly, this is probably extremely elementary. For a lab, I was given the question: When we are sitting in a planetarium, where are ...
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### What would an astronaut on the moon experience if a 1 meter diameter meteorite struck the surface one km away? [migrated]

Would the impact result in sufficient gas expelled from the vaporization of the meteorite to carry sound waves a distance of a kilometre from the impact? Would the blast wave be sufficient to injure ...
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### regarding curvature of earth [closed]

i am having one doubt in earth's curvature.....this question may be dumb... How much we need to travel on earth to feel the curvature of earth. hypothetical case: for ex we are building a vehicle ...
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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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### Why do objects burn when they enter earth's atmosphere?

Why do all objects burn when they enter our atmosphere? is this because of our atmosphere composition? and does this happen on other planets as well?
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### Can redshift be measured using fourier?

Are there pictures that contain high enough dynamic width, so that amateurs can use fourier spectrum analysis to observe the redshift themselves? I know pictures usually are encoded using RGB and/or ...
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### if the big bang only expanded the universe when and how did it originate? [duplicate]

If the big bang expanded the universe from a singularity point, that means that there was matter before, so where and how did matter form for the first time if it's even possible to know such a thing? ...
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### How can we infer the mass of SMBH in galaxies that are not active anymore?

I know it is possible to infer the mass of a supermassive black hole (SMBH) by many methods, i.e., stellar orbits for out Galaxy, Iron line profile from the accretion disk, and probably other methods ...
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### Do black holes die?

I know of stars actually dying (exploding as a supernova) but I have never heard of what happen to black holes. Do they continue to live forever, waiting there for more matter to absorb? Do they ...
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### Can someone explain a Geostationary Orbit in a simpler way?

According to Wikipedia (link), a geostationary orbit, geostationary Earth orbit or geosynchronous equatorial orbit (GEO), is a circular orbit 35,786 kilometres (22,236 mi) above the Earth's equator ...
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### To what extent are structure formations unexplained?

I hear conflicting claims about our understanding of the structure formation in our universe. I heard that ΛCDM explaines well the large scale structure of the universe i.e. Comparison of the ...
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### What does black hole evaporation correspond to in the accelerating universe / black hole analogy?

In the same way, as a black hole emits Hawking radiation corresponding to its temperature $$T = \frac{\hbar}{r_{BH}}$$ the accelerating universe can be described as all of the stuff falling ...
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### What are the masses of the two stars (given the information provided)?

If anyone would at least be willing to point me in the direction of finding the answer, or help me solve it I'd appreciate it. I don't know how to go about this, and need to know how to solve this on ...
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### Is it possible to calculate the time of day given latitude, longitude and solar elevation angles (zenith, azimuth, elevation)?

I am trying to determine the time of day of some images I have. I know the lat/lon, the day and year of image. I also know the 3 solar angles (zenith, azimuth, and elevation). Is there MATLAB or ...

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