4
$\begingroup$

I have a question concerning AstronomicalData. If I want the declination of the moon for a given date, I use:

AstronomicalData["Moon", {"Declination", DateObject[{1985, 11, 4}]}]
(* Quantity[27.0, "AngularDegrees"] *)

so this works very well.

When I try to obtain the longitude of the ascending node for a given date:

AstronomicalData["Moon", {"AscendingNodeLongitude", DateObject[{1985, 11, 4}]}]

Mathematica tells me that {"AscendingNodeLongitude", {1985, 11, 4, 0, 0, 0.}} is not a known property, but it is listed in the list of properties.

Can someone tell me what I do wrong here ? How can I get the longitude of the ascending node for a given date?

$\endgroup$
4
  • 1
    $\begingroup$ The documentation mentions that, since Version 10, AstronomicalData has been superseded by PlanetData, StarData, etc. After some digging, I found that the following syntax works for some properties: Entity["PlanetaryMoon", "Moon"][Dated["AngularDiameterFromEarth", Yesterday]], IN particular, it works for properties that change in time, but it returns an unclear error for immutable properties (like e.g. the name of the satellite). $\endgroup$
    – MarcoB
    Commented Mar 20 at 19:16
  • 1
    $\begingroup$ As a side note, I find the bewilderingly verbose and continually changing syntax to access the curated data so cumbersome as to make it practically impossible to use. $\endgroup$
    – MarcoB
    Commented Mar 20 at 19:18
  • $\begingroup$ Dear Marco, Thanks for your help ! Indeed bewildering syntax ! I had already tried your suggestion using Entity, but it is the same problem. I get a result when asking for "Declination" or "AngularDiameterFromEarth", but it does not give me a result for "AscendingNodeLongitude", which is strange because it is in the list of properties. Any Idea what could be wrong there ? Thanks ! Werner $\endgroup$ Commented Mar 20 at 21:03
  • $\begingroup$ AstronomicalData can report the time variation of some properties, like "Declination", but only has fixed values for other properties, like "AscendingNodeLongitude", though in reality this physical property varies in time. AstronomicalData refuses to accept a date for those properties that it treats as constant. $\endgroup$
    – jose
    Commented Mar 20 at 21:12

1 Answer 1

3
$\begingroup$

Versions 13.2 and later of Wolfram Language have much better support of instantaneous positions of planets and moons. In your case, this is a more precise value of declination for the Moon:

In[]:= AstroPosition["Moon", {"Equatorial", DateObject[{1985, 11, 4, 0, 0, 0}]}]["Declination"]
Out[]= 26.5464

with the result in degrees. We don't yet have functionality to report orbital elements, like the "AscendingNodeLongitude" property you are looking for.

$\endgroup$
1
  • 1
    $\begingroup$ Dear Jose, Thanks for the clarification. Looking forward to having all orbital elements in the future ! $\endgroup$ Commented Mar 20 at 21:56

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.