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Questions tagged [fundamental-astronomy]

Questions involving basic astronomical concepts or information.

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Can I learn astrophysics and astronomy with my basic math?

I want to learn astrophysics and astronomy, I'm very interested in it because there are many questions that popped up in my head, and really curious about things, but I'm afraid of a little bit on ...
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0answers
39 views

Question on dec 2013 answer to“How to measure the altitude and azimuth of a star?”

I am looking at your response to the above question. You stated: For Northern Hemisphere, a star that is crossing the North local meridian (that is, between the Zenith and the North Horizon) the ...
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1answer
129 views

Massive degraded impact crater on Mercury - chemical evidence?

The planet Mercury has a myriad of impact features - this has been known for some time. However, observe in the following images, a relatively large 'High-Mg region' detected on the planet (below): ...
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3answers
10k views

If Earth is tilted, why is Polaris always above the same spot?

Why is Polaris, the North Star, always above (or near) the North Pole? If Earth is tilted, Polaris' path should be in winter 23 degrees away from its path in summer, or not?
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1answer
38 views

Basis of color index

As an amateur astronomer for 60 years and always as interested in the science as in the observing, I thought I had a pretty good understanding of the fundamentals. But I'm distance-auditing a third-...
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1answer
53 views

Necessary steps to calculate photon's path by using null geodesic equation

Can anyone please give me an explanation on how to calculate photon's path by using the null geodesic equation? N.B. I know all of the non-zero values of Christoffel symbols.
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2answers
89 views

How to determine the eccentricity, knowing the orbital speed and distance

How to determine the orbital eccentricity of a planet, knowing the instantaneous orbital speed of it and the distance from the Sun to the planet at that moment?
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3answers
104 views

Does any asteroid we have ever seen have a hot core like earth.?

I was wondering if any of the asteroids we have ever seen has a hot core like Earth's. I'm thinking that Earth has a strong gravitational field and so formation would have involved a lot of ...
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3answers
1k views

Where to obtain Tycho Brahe's data?

I would like to obtain Tycho Brahe's data on Mars. What would be an authoritative source? One source I could find is this page (the data is given as an Excel file) but I have no idea can that be ...
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1answer
72 views

Making sense of the lomb-scargle periodogram

I am trying to use the periodogram to tell when a signal is periodic or not by following the tutorial for the astropy Lomb-scargle periodogram here. http://docs.astropy.org/en/stable/stats/...
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1answer
70 views

How to calculate declination of Moon?

Is there any way to calculate declination of Moon for any day?I'll subtract inclination of Earth on the ecliptic from the result. I'll get Moon's the shortest angular distance from Sun. Thanks for all ...
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3answers
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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 ...
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1answer
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Why the more-luminous star has larger surface area when two stars have the same temperature?

If two stars have the same temperature but one is more luminous than the other, the more-luminous star must have a larger surface area, and therefore a larger radius than the dimmer star. The ...
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3answers
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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 ...
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1answer
110 views

Does weight influence Earth's spin? [closed]

If put enough weight on a particular point on Earth's surface disturbing the balance between hemispheres, is it possible that the Earth's spin could change like an unbalanced spinning top?
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2answers
1k views

Where can I find/visualize planets/stars/moons/etc positions?

What resources are available to find the positions of planets, stars, moons, artifical satellites, asteroids, and other heavenly bodies?
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1answer
67 views

What does half-lit means?

Aristarchus estimated the relative distance of the Sun and Moon by observing the angle between the Sun and the Moon (α in the diagram) when the Moon is exactly half lit. Angle β must be 90° for ...
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2answers
3k views

Which came first: Galaxies <=> Stars <=> Planets?

If a galaxy is defined as a collection of planetary systems (and all matter in between), and a planetary system is defined as a collection of planets circling a star (and all matter in between), and a ...
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1answer
42 views

How does one “use” the Pan-Starrs data?

I've seen that a large block of Pan-Starrs data has been released and is available on-line and how the distributors of the data expect professionals and the general public to use the data in their ...
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1answer
44 views

Luminosities and Apparent Brightness of Two Stars of which one is 8 times the distance of the first star [duplicate]

Suppose two stars have the same apparent brightness, but one star is 8 times further away than the other. What is the ratio of their luminosities? Which one is more luminous, the closer or the further ...
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1answer
42 views

The Luminosity of two stars with same brightness but at different PC away

Stars A and B are both equally bright as seen from Earth, but A is 120 pc away while B is 24 pc away. Which star has the greater luminosity? How many times brighter is it?
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1answer
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What's the useful magnification for a scope with 70mm objective lens?

Some of the spotting scopes which are e.g. 70mm claim to magnify terrestrial objects at 75x. But yet they cannot produce sharp and clear images at even 30x-35x. While 90mm scopes can do a better job ...
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1answer
81 views

Why do most of the myths behind constellations originate from Greek? [closed]

Why do most of the myths regarding constellations happen to have begun from Greek civilization? Why not other civilizations? Most people who lived in the past era probably observed star patterns in ...
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1answer
54 views

Simulating Noise in Astronomical Images

I want to add realistic noise to a simulated image but I am a little confused about the process. I want to have some Gaussian random noise representing the readout noise and to also add Poisson noise ...
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3answers
554 views

Is there a flaw with the newer purposes and correlations attributed to the HR diagram? (And would a third axis of mass correct the enclosed flaw?)

When I was younger, I was looking at HR diagrams, and began to experiment with the HR diagram. I was looking at plotting different groups of stars on the HR diagram when I found RV Tauri stars. ...
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0answers
38 views

Any ideas for an astronomy + ML project? [closed]

I wish to do an astronomy related project which incorporates machine learning.Do you have any suggestions?
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2answers
80 views

How to find the radius of a satellite not knowing the mass

If I know the semi-major axis, the density of the planet, and orbital period.. how can I find the radius of the satellite? I can't think of any formula to use.
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1answer
6k views

How many astronomers are there in the world today?

How many now living individuals have a PhD in astrophysics, or by some other definition can be reasonably classified as astronomers? I think Richard Feynman once said that only one in a million is an ...
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0answers
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How strong are the stellar flares on YZ Ceti?

Doing research for a game and trying to understand the implications of the stellar flares from YZ Ceti. In short (ignoring the planets for now), if people were to build large space stations of various ...
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2answers
373 views

What liquids can be found in the void space?

Is there any material natural or otherwise a free floating liquid that can exist in space? https://space.stackexchange.com/questions/32274/what-liquids-last-the-longest-in-space
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1answer
40 views

Obtain IR diffuse data from WISE

I need some help obtaining IR background diffuse data from the WISE observation. There is already some work done in this regard; see: http://wise.skymaps.info/ . These are .fits files. How do I find ...
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2answers
177 views

What was the length of the solar day 73 million years ago?

How could this be estimated, or how accurately could it be extrapolated from a present-day measurement of the Earth's spin-down rate?
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2answers
221 views

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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1answer
61 views

Need help with the calculations/conversion of a celestial object

I'm developing a telescope controller open-source application. I started this project with a very little knowledge of Astronomy. Basically, the app is going to send data to telescope over a wireless ...
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2answers
666 views

A curious relationship between lunar periods and the solar year

Earlier today I was exploring the astronomy features on WolframAlpha, when I stumbled upon an intriguing numerical relationship involving the values for the lunar synodic and sidereal months. Using ...
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1answer
320 views

Numbers 80 to 85 in Ancient Astronomy

Do any numbers in between 80 and 85 (or thereabouts) hold any relatively important or relatively obvious meaning in ancient astronomy ? A few clarifications: By ancient I mean related to human ...
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1answer
86 views

The Solar Motion and the peculiar velocities of stars

Local standard Of Rest is the hypothetical origin of a reference system with respect to which the motions of all stars in some neighborhood of the sun average out to be zero which type of motions of ...
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1answer
72 views

What factors determines the size of a galaxy?

Recently i saw a post comparing sizes of different galaxies with the Milky Way. The largest one being the Ic 1011.What makes this galaxy so large? What factors decide the size of a galaxy?
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1answer
141 views

Equation of the Center constant factor

This questions concerns the longitudinal aspect of the Equation of Time, also called the Equation of the Center. In some sources the equation looks like the following: $\nu - M = 2\varepsilon \sin M$ ...
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2answers
223 views

Planetary reference systems and time

I am researching into how coordinate systems of solar systems objects are created by reading some of the reports written by the Working Group on Cartographic Coordinates and Rotational Elements (e.g. ...
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3answers
218 views

Directions to Proxima Centauri

I'm writing a sci-fi novel in which humans venture to the stars for the first time. Their "shake down" cruise takes them to Proxima Centauri. I'm trying to understand where Proxima Centauri is located ...
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2answers
329 views

Why does each and every planet of our solar system have an unique axial tilt angle?

Why do planets have an axial tilt? From the above image we can see that each planet's axial tilt angle varies and differs from the others. What was the cause of this, was this from the beginning of ...
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3answers
106 views

Account for radiation energy in the statement “total energy of universe is zero”

I've read in Hawking's book The Theory of Everything that total energy of the Universe is zero. He explained this by saying that if there are two bodies separated by a distance and having some mass, ...
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1answer
52 views

When black holes forms out of a supernova do they have a very high velocity?

When black holes forms out of a supernova do they have a very high velocity ?? Or do they remains at the position of parent star ??
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3answers
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Relation between angular resolution and aperture?

The angular resolution of a telescope is given by $\frac{1.22\lambda}{D}$. This should mean that the smaller the aperture D, the higher the angular resolution. But it is exactly the opposite - why?
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1answer
43 views

Photometric redshift

I have decided to do undergraduate thesis on "estimating photometric redshift" or something related to this using machine learning. Reading previous papers, I have come to know that work has been done ...
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4answers
108 views

Tips for a beginer who wants to learn more about astronomy [closed]

I have completely no idea about astronomy, but I am starting growing interest in it as I have been always wondering on what has been discovered out there and since I am studying CS, maybe I will learn ...
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2answers
555 views

What is the effect of the axial precession on the orientation of the planet's orbits?

I am working on an online application to visualize the positions of the planets and to calculate their ephemerides (you find it here, but it is not complete yet). I do not have much knowledge in ...
3
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1answer
130 views

Flatness of celestial systems like galaxies and Solar System [duplicate]

If we look around the cosmos, we will see most of the systems are just flat disks. Either it is solar system, galaxies, or the rings of Saturn. What is the matter, does it depend on how they were ...