# All Questions

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### Term for the period between planet alignments?

Is there an established astronomical term for the period of time between alignments of pairs of planets? For example, Mars, Earth, and the Sun roughly align ever 780 Earth days. In my writing, I've ...
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### period of an eclipsing binary

I am confused about the definition of the period of an eclipsing binary, a binary configuration where one component crosses the other across the line of sight. When people say that an eclipsing binary ...
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### orbital angular momentum and the longitude of ascending node

Consider the motion of a planet around an oblate star. Because of the oblateness the star has a non-zero quadrupole moment which causes the orbital angular momentum of the planet to precess around the ...
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### Are the Voyager spacecraft outside of our Solar System? [duplicate]

The wikipedia says that Voyager 1 cross the heliosphere, but is really outside the Solar System, or need to cross the Oort cloud?
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### Is a swimming pool analogy to building of black holes in the centers of galaxies valid?

In our garden, we have a little pool to enjoy our 2 children. It is 3 meters in diameter and contains some 4 m³ of water. For cleaning-convenience every evening I go walking some 5 or 10 rounds in ...
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### Why does light from objects take time to reach us? [duplicate]

Why does the light of objects such as the Sun, stars etc. take time to reach us? E.g. Why does sunlight take 8 minutes to reach us, instead of reaching our eyes as soon as it rises.
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### Black hole at Galactic Center of the Milky way and Bar of stars?

The Milky Way is a barred spiral galaxy, with a supermassive black hole at its center. Here As it is a barred spiral galaxy, it has a central bar-shaped structure composed of stars.Here So my ...
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### Why are tides biggest during the equinoxes?

I've read that during the equinoxes, tides are at their maximum. Shouldn't this only apply to latitudes near the equator? I mean, when the solar declination is near to 0º and we have a full or new ...
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### Do galaxies change shape and size over time?

Galaxies come in different shapes and sizes. What factors determine the shape and size of a galaxy, and how can these change over time?
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### How does Astronomy, amateur and professional, contribute to humanity and a better world? [migrated]

I think this is a good question to ask. There are possibly many aspects to this question. Astronomy and seeking knowledge has lead to the development of space probes, space science, development of ...
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### Does Earth transit look like a black dot surrounded by red light?

As we know, lunar eclipse appear red, if we can see Earth transit from Mars, does it look like a black dot surrounded by red light on the sun?
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### Can there be elliptical rings around a planet?

The rings of Saturn and Jupiter are circular. Orbits can be elliptical, so can rings be elliptical?
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### How are heavier elements such as carbon and silicon distributed within the Sun?

In a previous question I asked about the source of carbon and silicate dust that Solar Probe Plus will encounter in its close flyby of the Sun. It seems likely that most sources would include infall ...
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### Best format for analyzing and comparing coordinates across multiple tables

First coding project so if I am asking something wrong or asking too much please let me know. ANY help or advice would be greatly appreciated, including how to better word this question if necessary. ...
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### Why can we trust Hubble Time if the rate of expansion is not constant?

The age of the Universe can be estimated from taking the inverse of the Hubble constant: $t_\text{universe} = 1/H_0 =d/v.$ It seems to me this method assumes that any given galaxy has been receding ...
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### What is the origin of the dust near the sun?

In this question I asked about the Solar Probe Plus mission. Reading a 2008 report I saw that there is an elevated exposure to high velocity dust near the sun. I understand the high velocity, anything ...
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### Is the radius used in the formula for the escape velocity the average radius of the celestial object or the radius at the starting location?

I learnt that the escape velocity is given by $$v_e = \sqrt{\frac{2GM}{r}}$$ Say I want to launch a rocket from the earth into space and want to calculate the escape velocity $v_e$ (I guess without ...
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### Why does the Moon appear gray when passing between the Sun and the Earth?

Shouldn't the Moon appear as bright as a full Moon seen at midnight from Earth? The photo was taken by DSCOVR at Lagrange point 1. In the picture, The Moon appears dark gray. Of course the Earth ...
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### Refraction by Saturn's atmosphere - how dense is it here?

This tweet from CassiniSaturn shows an image of Saturn's rings being optically distorted by the dense atmosphere. It is explained more fully on this page and is available here. The refraction is ...
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### Can't find Cassiopias Schedar or Caph in Tycho-2 catalog supplement 1

I'm trying to locate three stars inside Cassiopeia, gam cas, Schedar, and Caph. I have found gamma Cas inside the Tycho-2 catalog supp1.dat file, however when I look for Schedar or Caph I have no luck....
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### Is the sun really white? [on hold]

"If you could travel into space and look at the Sun without going blind, you'd find that it's actually white, and not yellow" "White light is composed of all the visible colors in the electromagnetic ...
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### Weird light in the sky, curious as to what it is [on hold]

One night (a couple days ago) I looked out my bedroom window and saw a red light. It was fairly big but obviously not close to the window. It was moving, back and fourth between the distance of a ...
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### Parts of the Universe Shows Fewer Named Stars [duplicate]

I'm becoming interested in the currently identified stars in the universe. There is a wide swath where much fewer named stars are shown. Why is this? The image below is a mollweide projection of the ...
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### Is this a real picture of the moon?

I found this picture and I am really wondering if it is possible for the moon to get as close to the earth as this picture shows? ( Super moon above Rio De Janeiro)
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### Current communication delay to mars [migrated]

I'm not sure if I should ask this question here or on the Space Exploration Stack Exchange. If I'm on the wrong network here, please let me know. I read that the communication delay between earth and ...
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### Using SkyChoord to read in multiple coordinates.

so I recently wrote a basic code to analyze the distance between two points which are stored in two separate excel files. Now that I have that code working its time to apply the legitimate use and use ...
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### Jupiter, Saturn, Uranus, Neptune system GM

I'm modelling the solar system. I'm using data from Nasa. To do this I'm using the barycenter of the planets Jupiter, Saturn, Uranus, Neptune. However the website fails to give the Gravitational ...
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### How far away is the nearest compact star remnant likely to be?

Neutron stars and black holes are hard to detect when they are solitary, and there seems to be big uncertainties about how common they are. White dwarfs are much easier to detect and the nearest one ...
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### More than 67 Jovian moons?

Wikipedia says that there are now 67 known moons of Jupiter. It got me wondering: is it really possible in our day and age that there are more, but we haven't observed them yet? On the other hand, ...
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### What is the temperature of the solar atmosphere (the corona) and how is it measured?

The temperature of the Sun's atmosphere, also referred to as the solar corona, is known to be hot even hotter than the Sun's surface. What is its temperature and how is it measured? How does it ...
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### Is remote measurement of isotope ratios possible, or must a sample be aquired

Is it possible to measure to measure isotopic abundance of remote astronomical objects - ie measurement without having a sample to feed into a mass spectrometer? Do different isotopes show any ...
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### Planets, gem stones and their psychological effect on society [closed]

I have been having a pretty bad events happen to me lately. Any new undertaking turns sour. Situations that seemed to be getting better yesterday suddenly take a turn for the worst. For example I ...
40 views

### Bright two moving lights on the night sky [closed]

About a month ago, I was out with my friends, It was midnight, and We were watching a bright dot in the sky. It was shining more than the stars. (It is there everyday, cca. 3 years, before that it ...
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### Why did the Big Dipper form? [closed]

There is an asterism comprising 7 stars, known as Saptarishi mandalam, but better known to the Western world as the Big Dipper. It gets its name from the seven rishis. Why did this asterism form, why ...
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### Why celestial objects appear brighter in the night sky than in photographs from closer proximity?

The moon, for example, appears very bright in the night sky, but quite dark from photographs on/near its surface. Similarly, Mars and Venus appear as bright dots in the sky but in closer photographs ...
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### Is it possible that a star system ejects an object out of the galaxy?

I know it is possible that a star system ejects a planet out of the star system and the planets becomes rogue planets and orbit around the galaxy. Is it also possible that a planet gains enough speed ...
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### Interfacing FORTRAN programs for model atmospheres with IDL or Python

I'm trying to use model atmospheres such as Kurucz or MARCS for the first time personally and I'm wondering if it is better to wrap it with IDL or Python in terms of writing the code, and getting the ...
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### Stars in a straight line [closed]

I have observed many 2 stars which will be distant but seeing from here it will be in a straight line. Similarly 3 stars which is short distant to each other will be in a straight line. How is it ...
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### What is the projected range of the JWST to be able to detect exoplanet atmospheres?

Yesterday the K2 mission detected transit events of objects passing in front of a number of M dwarfs which could turn out to be rocky planets. If some of these planets host atmospheres, could the JWST ...
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### Can I get help getting image of Celestial Body at RA 2.220 and Declination +15.59?

My mom had a star named for my dad who died a few years back. I told her that I'd try to find an image of that star and send it to her. My dad's Birthday was 3/31/1931 if that helps. Would love ...
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### Galaxy centre X structure - could this reflect impact of black hole at galactic centre

As reported in this science article X Marks the spot Centre of Milky Way, a X shaped feature is confirmed centered on our galaxy's centre, when looking on from within the plane of the Milky Way. In ...
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### How far into intergalactic space would you have to go to see the Milky Way?

If in the distant future a ship were somehow able to move beyond the galaxy and into intergalactic space, how far would it have to go before we could look out a window and see the Milky Way in its ...
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### Do far away planets reflect light in the same way our moon/earth reflects light?

Here’s a scenario: Say you’re up in space and you’re far enough way that you can see the planet earth. Whilst looking down, you can see blue sky, blue water and green land and white clouds and ...
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### How often is a blue moon?

A blue moon is two full moons in the same month. How many times will a blue moon occur in the average lifetime of say 70 years?
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### New moon and full moon [closed]

When it is new moon we call it as amavasya . How does the moon grow and attain full moon. We call this as pournami. Again it is getting diminished. How does this happen?
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### How many stars would it take to draw a line across the middle of the sky that appeared solid?

I was talking with a friend about how slowly the star field changes (based on the speed that we are moving through the galaxy) and I started to wonder about a star's visible size. They are basically ...
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### Does Eddington's variable polytropic index better fit data from the Standard Solar Model?

I came across a 1938 paper by Arthur Eddington1 in which he discusses stellar polytropic models where the polytropic index $n$ varies inside the star, decreasing from a value $n_2$ at the surface to a ...
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### how can a supermassive black hole cause so much energy to enlighten its matter when its massive gravity prevents light to escape?

to cite this german newspaper: Das Materie-Monster sitzt den Angaben zufolge im Herzen der 42 Millionen Lichtjahre entfernten Polarring-Galaxie NGC 660, deren Aktivität innerhalb weniger Monate ...