# All Questions

6,947 questions
9 views

### Are there any kinds of binary pairings that haven't been discovered yet?

There are lots of possible objects. For simplicity's sake (i.e. to hide my ignorance) lets assume momentarily that there are only black holes, neutron stars, white dwarfs, brown dwarfs, red giants, ...
52 views

### What's the reason that we have different quantities of days each month?

It always was interesting for me to understand the answer for the question: What's the reason that we have different quantities of days each month? If the month is fixed on the time that the moon ...
15 views

### How to separate binary and optical stellar pairs?

I have list of stellar pairs from The Washington Double Star Catalog (WDS), i.e. I have next parameters: angular separations position angles stellar magnitudes of both components Additionally I have ...
70 views

### Is space a thing?

Based on my extent of knowledge relating to astrophysics, I once thought space is a thing, which can be twisted a long side with Time regarding masses of objects(According to relativity theory). But ...
28 views

### What could possibly save an atmosphere other than a magnetic field? Why can't a magnetic field save the atmosphere in certain cases?

Similar question here. We know as a fact that the magnetic field protects planets from Solar Wind, a damaging, continuous, atmosphere-stripping wind of charged ions. Thus, a magnetic field protected ...
41 views

### Could there be additional Neptunian satellites between Larissa and Hippocamp?

Plotting the moons of Neptune in terms of semimajor axis and eccentricity using the values given on the Wikipedia page for the moons of Neptune, there appears to be a fairly large gap between the ...
55 views

### Is the water on Mars drinkable? [on hold]

Could water from Mars be fresh enough to drink? Could one run the water through a home water filter? I understand when water is frozen the salt is ejected as brine so would newly formed snow or ice be ...
50 views

### Is gravitational lensing a good way to search for negative mass?

Is it possible to verify negative mass with gravitational lensing? The following video proposes an idea that galaxies are surrounded by negative mass: https://youtu.be/MZtS7cBMIc4 Could this be ...
69 views

### What would happen if a star went supernova inside a supermassive black hole?

A black hole swallows a star. The star remains intact. Then goes supernova. What would happen to the star? Could we detect this event?
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### What do the months and hours mean in Tomas Filsinger's Map of The Universe

I have had one of these in my room for decades: I don't have the booklet that seems to usually come with it, can someone explain to me what the months (with days below it) and hours mean? I imagine ...
38 views

### Determining the shape of ʻOumuamua via stellar occultation

As far as I know, our current knowledge regarding the exact shape and size of ʻOumuamua is based on the analysis of its light curve and the assumption that it has a uniform albedo. ʻOumuamua is very ...
98 views

### How would rainbows appear on other planets?

Are other planets capable of producing rainbows? How would those rainbows appear? Can rain, clouds or ice from elements other than water produce rainbows? Related: https://space.stackexchange.com/...
39 views

### Could you tell me this constellation name? [on hold]

Hi Everyone please check this pictures could you tell me this constellation name ?
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### Roche Zone of a black hole vs Roche Zone of Neutron Star

Suppose a very unusually small back hole with the mass of about, lets say, 1.5 solar masses(hawking radiation should destroy a lot of mass let's assume). It thus would have a Roche limit smaller than ...
122 views

### the movement of the moon

I was in Cuba from January 15th to the 22nd this year and there was a quarter moon. If I use a compass to explain the orientation of the quarter moon, it started in the north position around 4 pm. By ...
50 views

### Are there known centaurs which orbit between Jupiter and Saturn without crossing their orbits?

According to Centaur minor planet Centaurs are small Solar System bodies with a semi-major axis between those of the outer planets. They generally have unstable orbits because they cross or have ...
55 views

### Who was the first to realize that the Earth is surrounded by vacuum? [on hold]

My question isn't about the arrangement of planets in space (geocentrism / heliocentrism), nor the understanding of the whole universe (we are in a galaxy, there are galaxies etc). My question is: who ...
101 views

### Do interstellar asteroids decelerate and eventually stop?

I do wonder, do interstellar asteroids eventually stop at one point in space after they gradually decelerate (or) even do they decelerate? Though there is no air like on earth and thus asteroids ...
87 views

### What's going on in this photo of Halley's comet's tail?

When researching for this answer I was looking at Space.com's 2011 article Photos of Halley's Comet Through History I saw the image below, and read the caption. Halley's Comet in 1910 ...
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### Halley's Comet current location in sky and visibility?

I am an amateur in astronomy, but recently I wonder if it is possible to see (in a photo, maybe, if not in a telescope) Halley's Comet when its not close to earth. If there is such photo, how I can ...
61 views

### What I can observe with a 80/900 refractor telescope? What can I study?

Recently I bought a telescope after a very good conversation with an astronomer friend of mine. The main goal is to see planets. However, Mars is so difficult and is far to find it in opposition. I ...
50 views

### Which is the farthest distance a particular distant known- identified object from the asteroid belt can get from the sun?

According to Space facts The Asteroid Belt is located in an area of space between the orbits of Mars and Jupiter. That places it between 2.2 and 3.2 astronomical units (AU) from the Sun But ...
83 views

### What is so special about the Ultima Thule passed by New Horizon spacecraft?

I read that the New Horizon spacecraft passed by the Ultima Thule. I also got to know that it is a flat, snowman-shaped rock. What is so special about it?
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### How to calculate the argument of perihelion for exoplanets with incomplete orbital elements?

I'm trying to simulate the Kepler-444 exoplanetary system using data from this website. The problem is that there is no argument of periapsis parameter for the Kepler-444 system, so while I think I'm ...
67 views

### Are galaxies moving in each direction with same speed?

All galaxies are moving away from each other (us) because of the expansion of the universe. Are they moving with same speed in each direction?
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### White Dwarf/Degenerate Gas Behaviour

just want to try to clarify a few things about the nature of White Dwarfs and degenerate gases. So if a white dwarf is help up by an electron degenerate gas, the electrons are unable to lose energy ...
43 views

### Star rotational axes and Solar system orientations

How does the orientation of stars axes of rotation and any planetary systems relate to the plane of the galaxy? Is there any relationship that has been detected, are they grouped from their parental ...
22 views

### Asteroid identification in fits image

I have a fits image, and I need to identify an asteroid. What characteristics do I look out for?
85 views

### How come the Sun does not make the Moon crash on the Earth?

As the Moon loops around the Earth, on one side of the Earth it moves toward the Sun (let's call it downward side) and on the other side it moves away from the Sun (let's call it the upward side). ...
43 views

### Historical Distance of Planets to Earth [duplicate]

I'm curious if there is a readily accessible tool available, or simply a reliable way to find out what the distance of the planets in the solar system were on a given date. For example, if I am ...
57 views

### What's the proportion of Mars' surface compared to Earth's surface uncovered of water?

How does Mars surface compare to Earth's surface? Mars is quite smaller than Earth, but most Earth's surface is covered with water. I thought making the math could be relatively easy but Earth isnt a ...
37 views

### Mass of the universe

How do we calculate the mass of the universe taking into consideration dark matter? Mass of visible matter can be computed by stellar method, but how do we calculate mass of dark matter which we don'...
45 views

### Motivation for using $\sigma_{8}$?

Press-Schechter formalism allows one to universally quantify the number of massive dark matter halos in a given volume -- The Halo Mass Function. The density contrast is given by the rms mass variance ...
21 views

### Change in declination due to precession

If the presenet declination(0°) and R.A(3 h) are known , when will the declination have the same value again?
4k views

### Is there any known moon of a moon? [duplicate]

As far as I understand, a moon is an object in permanent orbit around a planet, dwarf-planet, asteroid, etc. If there was another object permanently orbiting this moon, would that be a moon-moon? Is ...
41 views

### How long a photon stay suspended in orbit around a black hole?

Can a black hole free from an accretion disk collect photons in the photon sphere in a prolonged stable orbit? Could enough photons be in orbit to shade the actual black hole with light? Would a ...
49 views

### Found green rock 20cm below surface, is this an meteor piece? [closed]

I am wondering if this rock on picture below is meteor fragment? If so what composition you think it is? It is magnetic i tried with magnet and it sticks to it very strong, it does have a lot of mass.
30 views

### Finding the diameter of a molecular cloud using period of intensity variation of hydroxyl maser

So I have this problem (which I translated to English as accurately as could): When studying a compact molecular cloud with radiotelescope, at a wavelength of 18 cm, hydroxyl (OH) maser(ic) ...
48 views

### How to calculate the time of Ekadashi days?

Is there an official reference algorithm for calculating the Ekadashi days? I found the textual description of Ekadashi calculation on wikipedia but can't really make sense of it in order to write ...
59 views

### How do we know that the mass ratio of hydrogen and helium in the sun is approximately 3:1?

From what I learnt, we can find what elements are in the sun by analysing spectrums since each elements has same emission spectrum, and when you look at the sun's spectrum, you can see absorption ...
35 views

### Astronomy/Astrophysics Project With C++/C/Python [closed]

I am a Computer Science Engineering student, in the 1st year of college. I'm insanely interested in making a project regarding astronomy/astrophysics but I don't know where to begin from. I know C, C++...
100 views

### Why do sun spots appear near the equator of the Sun?

I noticed on many examples sun spots are near the equator of the Sun. Why are there no sun spots closer to the poles of the Sun?
284 views

### Why the Circumstellar Habitable Zone is defined as it is, if life could be possible outside of it?

According to Circumstellar habitable zone In astronomy and astrobiology, the circumstellar habitable zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a ...
62 views

### How was Cruithne's orbital time calculated?

How was it determined that Cruithne takes 770 years to complete its cycle with Earth? Janus and Epimetheus were disovered long enough ago, and have short enough cycle times, that we've had time to ...
51 views

### What causes random irregularities in the earth's rotation accounted for by dynamical time

I read in a book that the earth's rotation sometimes shows unpredictable irregularities(not caused by precession, nutation, tidal forces) which are accounted for using dynamical time. What would be ...
71 views

### How does making a refracting telescope very long reduce the chromatic aberration of an uncorrected lens?

Below are two cropped views of "Johannes Hevelius's 8 inch telescope with an open work wood and wire "tube" that had a focal length of 150 feet to limit chromatic aberration." from Harvard University, ...
70 views

### Can rogue/nomad planets and other starless planetary bodies orbit each other in a stable system?

Nomad planets (also called planemos or rogues planets) which drift in space without a star or substellar object to orbit. The majority of such planets we have discovered are gas planets with thick ...
71 views

### How can you verify the science presented on TV shows like “How the Universe Works” is current or valid? [closed]

What resources are there available where I could verify current scientific thinking on the origin of the universe theories?