Questions tagged [positional-astronomy]

Questions about positions of objects in the sky, either relative to a fixed coordinate system like the equatorial and ecliptic coordinate systems, or relative to an observer's point of view.

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2
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1answer
419 views

Will time that moon crosses meridian always be periodic?

If I observe the moon pass my celestial meridian at a specific north polar clock 'time' will I observe every subsequent passage at ( 'current time' + 13.2* X 'days passed' mod 360* ) ? Does the moon ...
2
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1answer
320 views

What should be the declination of a star to be marginally circumpolar given the latitude & height from ground?

If I'm given the latitude, I can easily find the declination by using declination = 90 - latitude. I can also find the angle of dip from the height but should I add or subtract it from the declination ...
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1answer
60 views

Calculate NEO object position with nasa Near Earth Object data

I wish to create a 3D visualisation of NEO's by date in relation to earth, but calculating their position at that time has got me stuck. From this question I was able to fine Nasa's NEO object data: ...
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0answers
159 views

Viewing “Diamond Fuji”

Diamond Fuji is a phenomenon in which the (typically) setting sun is positioned directly atop Mt Fuji. Some relatively detailed predictions for viewing times at a nearby park are available here. I ...
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3answers
2k views

Generate an uniform distribution on the sky

How to generate an uniform distribution of stars on the sky ? What I want is make a simulation of random points following uniform distribution on a part of the sky (making the assuption that we have ...
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1answer
135 views

Measuring declination in negative hours of arc?

I'm running the program found at https://www.projectpluto.com/source.htm in order to find the Right ascensions and declinations of celestial bodies at various points in time. An odd thing I've noticed ...
3
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1answer
320 views

How to visually chart HORIZON ephemeris

I'm trying to build a 3D model of the Sun, Earth and Moon in in Javascript (using Three.JS, which relies on x,y,z coordinates for all objects) in order to simulate the Aug. 21 eclipse. I've ...
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3answers
102 views

What of the following moon-situations would be better?

Okay, so imagine that there is an Earth-like planet, with the following conditions: It's further from it's sun than the Earth is from the Sun (not much, but enough for weather to be a little colder ...
5
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1answer
90 views

What is the difference between ICRS and ICRS2?

When I first learned about Positional Astronomy (50 years ago), everything was described with respect to the Equator and Ecliptic (true or mean, of date or of a specific epoch). Then 'they' invented ...
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0answers
53 views

Does an algorithm exist that takes an image of the night sky and tell you where in the milky way that perspective likely originates? [duplicate]

In Stargate they talk about using the stars on other planets to figure out their location. I know that's fiction, but it made me wonder if such an algorithm (with arguably little usefulness right now) ...
4
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1answer
242 views

Stellarium simulation

I'm interested lately in Stellarium and the functionalities which it provides especially scripting. I want to make a simulation that shows the celestial sphere with some planets like Venus, Mars, and ...
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2answers
323 views

Is it possible to figure out your location in the Milky Way if you are suddenly wormholed to a random, distant location in the galaxy?

If you were flying along in your spacecraft somewhere in our solar system and then a large, stable wormhole suddenly opened and you flew into it and were whisked away to some distant location in the ...
29
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1answer
4k views

If dark matter bends light, how do we know the stuff in the sky is where we think it is?

We measure movement, position, and many other things of an object in space because of its light and what we can measure with it. But as far as I know there's supposed to be a HUGE amount of dark ...
3
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1answer
384 views

About the formula for taking in count of the observer altitude in sunrise/sunset formula

I'm new here and searched for solution but did not found one. I have found algorithms in order to calculate sunrise and sunset times for an observer on the surface of Earth with explanations of ...
11
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1answer
346 views

How the position of this black hole known?

How do scientists know the positions of black holes? Observe the highlighted area in the image:
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2answers
526 views

Declination of the Sun formula

I encountered a book discussion that defines the Sun's declination as 23.5 degrees (inclination of Earth's equator to the ecliptic) times the sine of the Sun's longitude. Does this make sense? How do ...
3
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2answers
460 views

Length of a tidal day or by how much is the Moon late each day?

A tidal day is the MEAN time between successive meridian transits of the Moon. (This is sometimes called called a lunar day, a term that should be deprecated for use in this sense, because it is also ...
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0answers
59 views

Attempting to determine astronomy values in a parameter file

Recently I inherited quite a few old QuickBasic programs which perform various astronomical calculations. I'm attempting to understand these programs and rewrite some of them in Python. I do not ...
2
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1answer
98 views

Centre (projected) of a galaxy cluster

A galaxy cluster consists of somewhere around a few tens to several hundred galaxies. To measure the position of a galaxy cluster, i.e. it's RA and DEC, do astronomers always assume it to be its ...
2
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2answers
653 views

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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1answer
2k views

What is the Galactic Latitude and Galactic Longitude? How is different from the latitude and longitude we use on Earth?

It has to something with the positioning of sun and galactic center of the milky way but I wasn't able to understand how for a given star, its co-ordinates are calculated. Some explanation would be ...
0
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1answer
506 views

Moving-Cluster method for determination of the distance of Hyades. A starter problem

I am currently following a class of observational astronomy lab. I will present a brief description of the method in first and then proceed to the question, so anyone is welcomed to read the entire ...
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2answers
485 views

Question on Equatorial and Galactic coordinate systems

I'm currently working with proper motions and have needed to convert my galactic longitude and latitude into right ascension and declination (ie from galactic to equatorial coordinates). This is fine ...
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2answers
119 views

Are Wikipedia's sun ecliptic-coordinate formulae accurate?

I'm creating a C++ program that calculates the ecliptic coordinates based on the formulae from Wikipedia But, my calculations appear off. The mean anomaly for today, for example, should be 80.4-...
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2answers
946 views

Solar / lunar positions in ECEF using SOFA C libraries

I'd like to calculate the positions of the sun and moon in the ECEF coordinate system using the SOFA (http://www.iausofa.org/current_C.html) libraries given a Julian day input. So far, I've got this ...
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1answer
103 views

SDSS. Google Sky and DeCaLs

(1) Please go through following image Possible Super Red Giant? However sdss shows it as galaxy! Am I missing something. (2) Google Sky shows object in latitude and logitude format like this. Is ...
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1answer
262 views

Angular distance/apparent separation between AE Aurigae and Orion's belt

The title perhaps gives the question away, but would anyone know/be able to roughly approximate the angular distance/apparent separation between AE Aurigae and Orion's belt. I have the value of $42^\...
27
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2answers
2k 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?
3
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2answers
887 views

Why do stars seem not to move relative to each other?

Whilst I understand why stars move across our skies,(Earth rotation) I struggle to understand why they do not appear to move relative to each other. To explain: Take the best know constellation the ...
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1answer
370 views

Obtaining stars vector position in relation to the center of the galaxy at a given date

How can someone obtain such vector, for stars in the Milky Way? Input should be star data (from a catalog, eg: Hipparcos) and Julian Date. Output should be a Vector Position (in pc) in relation to ...
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2answers
1k views

Get date and time by position of the sun and the observer position

I am working on an astrology project (don't panic, my question is about astronomy or math), where I need to figure out some values by the longnitude of the planets. I have a program for this, the ...
2
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1answer
243 views

Where can I look up the 3D positions of the closest stars? [duplicate]

The problem: I want to simulate a travel from Earth to the closest 15-25 stars. Which is the fastest way to accomplish this? What i have: I currently have the distance between Earth and the nearby ...
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1answer
330 views

relation between azimuth angle of the sun and angle of the shodow

What is the relation between azimuth angle of the sun the bearing of an vertical object's shadow? For example if the bearing of the shadow is 75° can we conclude that azimuth angle of the sun is 195°?...
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1answer
1k views

Finding a location using the direction of shadow, UT and date approximately

Does anyone know how to find a location by using : the direction of shadow relative to the normal (for example azimuth angle) the Universal time (UT) and date I have a satellite image and I know ...
3
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1answer
175 views

Can we draw a min(distance) and max(mass) relation based on current observation data of nearby astronomical objects within several parcsecs?

The data precision now can exclude a >>$1M_{\odot}$ black hole companion, which has a, say 10000 year orbital period with our sun? Can we draw a two dimensional diagram(Mass VS. distance) to show the ...
2
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1answer
153 views

Finding the suns position in the sky anywhere at any time

What am I looking for? from any point Latitude, Longitude and date D I want to know where the sun is in the sky at any given time anywhere on our planet. I even don't know what the outcome will be ...
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2answers
468 views

Real-time position of a distant celestial body

How might it be possible to determine (via some specific online empemeris or via some well-understood algorithm) the observed position of some distant celestial body (e.g. Betelgeuse)? To be concrete:...
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2answers
1k views

Where to get Polaris Right ascension value from

To calculate for example the polaris hour angle I use this formula to calculate polaris hour angle. τ = θ - α τ= hour angle θ= sideral time α= polaris RA (~ 2h32m) But where does the α=2h32m come ...
7
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3answers
592 views

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?
4
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1answer
273 views

How do you calculate length of day in a multiple-star system?

How can you calculate the length of day for a planet (given a particular latitude and longitude on that planet) orbiting multiple stars? What about a planet that is orbiting one star, but that star ...
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3answers
1k views

Calculate time when star is above altitude 30°

To find the best observation time for an object, I'd like to calculate the time when it is 30° or more above the horizon. Local Sideral Time would be sufficient. To include that in my program, I need ...
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2answers
2k views

Find constellation over Earth coordinates on a specific date-time

I would like some help in finding the exact constellations, or some sort of visualization of the stars over an specific location an time. The idea is to find out the closest star or group of stars on ...
3
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2answers
271 views

What is the Northernmost Latitude of Saturn?

My wife and I were watching a TV show last night, which takes place in Salem, Massachusetts circa 1693. One character went to a particular place in the woods at a particular time to be exactly under ...
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2answers
166 views

When is Gamma Draconis closest to the zenith in London on April 4th

I am reading Roobert Hooke's paper An attempt to prove the motion of the earth from observations (1674, faksimile). Hooke writes The principal dayes of doing which will be about the 4 of April, ...
3
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1answer
208 views

How do I get from Star Atlas to real life?

This question is about finding the elevation and bearing of a given star at a particular time at Latitude 52N. I look up the RA and Declination of my star. How do I calculate its bearing and ...
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1answer
285 views

Why is a star at its highest point when local sidereal time = RA (right ascension)?

I'm currently taking a course called Introduction to Astronomy at Coursera. It's not very formal so they didn't present a proof of the statement in the title. I understand why logically one could ...
4
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1answer
134 views

VSOP for exosatellites? (Io, Titan, Ariel, etc)

VSOP87 (and the subsequent VSOP2000 and VSOP2013) provide reasonably accurate planetary positions while still maintaining a small file size compared to the Chebyshev polynomial files. VSOP ...
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1answer
2k views

Calculating Angular Distance

Given the horizontal coordinates of two objects in the sky, how does one go about calculating the angular separation between them?

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