Any Galaxy (Milky-way) based coordinate systems?

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Discussion Overview

The discussion revolves around the existence and characteristics of coordinate systems based on the Milky Way galaxy, particularly in relation to the positioning of the Sun and other solar system bodies. Participants explore the implications of using different origins for these coordinate systems and their practical applications in astronomy.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant mentions the "Ecliptic coordinate system" and questions if there is a Milky Way-based coordinate system that accurately represents the positions of solar system bodies over time.
  • Another participant introduces the concept of galactic coordinates and provides links to resources for further information.
  • Concerns are raised about the designation of the Sun as the origin of the galactic coordinate system, with questions about whether the center of the Milky Way would be a more appropriate choice.
  • Some participants argue that a Sun-centered system simplifies calculations for observations from Earth, as it aligns with how the galaxy appears from our perspective.
  • Precision in the Sun's location is noted, contrasting with the uncertainty surrounding the center of the galaxy, which some argue makes it less practical as a reference point.
  • The relationship between the galactic equator, celestial equator, and ecliptic is discussed, highlighting their non-parallel nature.
  • One participant suggests that the choice of the Sun as the origin is based on convenience, given the proximity of solar system objects.
  • Clarifications are made regarding the distances involved, with one participant correcting a previous statement about the distance from the Earth to the Sun.

Areas of Agreement / Disagreement

Participants express differing views on the appropriateness of using the Sun versus the center of the Milky Way as the origin for coordinate systems. The discussion remains unresolved, with multiple competing perspectives presented.

Contextual Notes

Participants highlight limitations in precision regarding the center of the galaxy, which may affect its utility as a reference point for calculations. The discussion also reflects varying assumptions about the convenience and practicality of different coordinate systems.

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TL;DR
As the Sun also moves, how to find its absolute coordinates in the galaxy?
There is an "Ecliptic coordinate system" that represents the apparent positions, orbits, and pole orientations of Solar System objects.

But, the Sun itself is NOT having a fixed immovable positon:
- It moves around the barrycenter of the solar system
- It also revolves around the central black hole of our Milky Way galaxy.

Is there any Milky-way-based coordinate system that gives the position of the Sun/ other solar system bodies at any particualr time?

Is there any site/ software showing pictorial representation of such a "Milky-way-based" movements of solar system bodies?

Thanks.
 
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Baluncore said:
Galactic coordinates.
https://en.wikipedia.org/wiki/Galactic_coordinate_system
That seems weird to me. Why is our Sun designated as the origin of that coordinate system? Shouldn't it be the center of the Milky Way Galaxy instead? Does the Equatorial Coordinate System also use the Sun as the origin?

1722007586318.png
 
A Sun centred galaxy makes it easier to calculate what the sky will look like above our heads. To us, our galaxy appears to be Sun centred.
 
Also we know with pretty high precision where the sun is. The location of the center of the galaxy has very wide error bars (+- 0.8 kpc from Reid et al 2009, ApJ, 705, 1548) so it is pretty useless as the center for calculations.
 
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berkeman said:
Why is our Sun designated as the origin of that coordinate system?
The frame has been chosen for convenience. After all, none of us (including JWST) are more than a million miles from the origin.
 
sophiecentaur said:
After all, none of us (including JWST) are more than a million miles from the origin.
But we are 97 million miles away.
 
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Baluncore said:
But we are 97 million miles away.
I should have said "apart".
We orbit the Sun regularly so using the Earth would make it inconvenient to use Earth as an origin - a conversion would be needed for every observation. Using the Sun as origin must be the least worst choice, particularly for distances that can be measured in Parsecs (I think).
 

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