Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Coordinate systems in the solar system?

  1. Feb 7, 2010 #1
    I have read the wikipedia page regarding Celestial coordinate systems and searched on google, but I cannot find any coordinate systems which describe a planet's position in it's orbit. Does there exist such a system?

    An example use of this system would be in locating the planets in the sky. I know that Mars is near opposition now, so I would expect that Mars' coordinates in such a system to be whatever Earth's position is +~180°.
     
  2. jcsd
  3. Feb 7, 2010 #2

    russ_watters

    User Avatar

    Staff: Mentor

    That's an earth centered coordinate system, not a sun centered coordinate system. And it isn't how it typically works. The normal one uses the holds the background of stars fixed. It uses right ascention and declination. http://en.wikipedia.org/wiki/Celestial_coordinate_system

    What you suggest would hold the sun fixed. I guess something based on time would qualify, as the sun is due south at noon (therefore, Mars is due south at midnight right now).
     
  4. Feb 7, 2010 #3
    I did read that wikipedia article. But where can these coordinates for celestial objects be found, then? What is Mars' value at the moment, and where could I have looked that up myself?

    Thanks.
     
  5. Feb 7, 2010 #4

    russ_watters

    User Avatar

    Staff: Mentor

    Any decent planetarium program will give you the coordinates of an object. I use Starry Night.

    At this moment, Mars is at:
    RA: 8:39
    Dec: 23 degrees 3'
     
  6. Feb 7, 2010 #5

    D H

    User Avatar
    Staff Emeritus
    Science Advisor

    You might also want to read up on the International Celestial Reference Frame (ICRF, see http://rorf.usno.navy.mil/ICRF [Broken]) and Standards of Fundamental Astronomy (SOFA, see http://www.iausofa.org/index.html).

    As for coordinates for various bodies, the Horizons system at JPL is a very good reference. See http://ssd.jpl.nasa.gov/?horizons.
     
    Last edited by a moderator: May 4, 2017
  7. Feb 9, 2010 #6
    just something interesting:

    http://www.atticusrarebooks.com/jferg11.jpg [Broken]


    http://www.atticusrarebooks.com/jferg8.jpg [Broken]

    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=230432371491 [Broken]
     
    Last edited by a moderator: May 4, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook