1

Is it possible to get the ecliptic coordinates of orbits of planets for a specific date and time? Does the ephemeris data of planets help in constructing that? Any help on this would be helpful. I would like to get the planetary orbit data that I can plot in a map.

Tom Sol
  • 437
  • 3
  • 18
Rasika
  • 83
  • 5
  • 2
    Converting from RA & declination to ecliptic latitude and longitude is simple spherical trigonometry. See https://en.wikipedia.org/wiki/Celestial_coordinate_system for the relevant formulae. – PM 2Ring Nov 25 '19 at 21:17
  • 1
    Answers to Where can I find/visualize planets/stars/moons/etc positions? may be helpful. The two I find most helpful are the Python package Skyfield and[JPL's Horizons website.. – uhoh Nov 25 '19 at 23:35
  • If you are interested at all in using or learning Python then Skyfield works simply and nicely and can convert to ecliptic coordinates. If you'd like to try Horozons here's a tutorial and here's how to convert to ecliptic coordinates. Are either of these methods something that you'd like to try? – uhoh Nov 25 '19 at 23:42
  • 1
    @uhoh i know a bit of python, but will i be able to construct the orbit from the ephemeris data? – Rasika Nov 26 '19 at 01:37
  • @PM2Ring will i be able to construct the orbit from ephemeris data? – Rasika Nov 26 '19 at 01:52
  • @Rasika I'm a little confused by your comment because that's exactly what ephemeris data is for! Skyfield and Horizons use JPL's Development Ephemerides which are in essence just large tables of their own flavor of Chebyshev interpolation coefficients optimized to produce uniform low error no matter where you interpolate. Using either Skyfield or Horizons you specify your own series of time points and they will give you the positions of the object along its orbit. – uhoh Nov 26 '19 at 03:57
  • However, if by "construct the orbit" you mean to generate a set of fixed Keplerian orbital elements ($a, \epsilon, i, \omega$...) then no, these are by themselves not going to do that. These are meant to provide very accurate predictions at specific points in time taking into consideration all physical effects. Keplerian orbits are only approximate. Horizons does give osculating elements though. The more you explain about exactly the form of what you need, the more specific the answer can be. Here's what you can do w/ Skyfield for example – uhoh Nov 26 '19 at 04:04
  • and here's another example – uhoh Nov 26 '19 at 04:04
  • 1
    @uhoh actually i want to plot the orbit of planets on the earth for a given time and date, for that i need latitude and longitude correct? if we see a position of planet what we get is a single point , from that i cannot construct the orbit of it. please apologise if my question is wrong – Rasika Nov 26 '19 at 04:32
  • Let us continue this discussion in chat. – Rasika Nov 26 '19 at 05:29
  • @Rasika In that case Skyfield has a .subpoint() method that might do exactly what you need. Okay see you in chat! – uhoh Nov 26 '19 at 05:33
  • You asked a similar question earlier. The issue here is that the Earth rotates. The point where Saturn (for example) is overhead moves west at several hundred miles per hour and returns to nearly the same spot within 24 hours (closed to 23 hours and 56 minutes, a sidereal day). You can't really plot a skymap over an Earth map unless you compensate for the Earth's 'rapid' rotation. BTW, I'm working on a "map overlays" project which would include this, so feel free to ping me personally (contact info in profile). –  Nov 26 '19 at 15:31

0 Answers0