Skip to content

Correct one AU to 149597870700 m exactly#163

Closed
NoNameForMee wants to merge 2 commits intoesa:masterfrom
NoNameForMee:master
Closed

Correct one AU to 149597870700 m exactly#163
NoNameForMee wants to merge 2 commits intoesa:masterfrom
NoNameForMee:master

Conversation

@NoNameForMee
Copy link
Copy Markdown

1 AU per the IAU 2012 Resolution B2 and the BIPM published "The International System of Units (SI), 9th ed."
Table 8 of "Non-SI units accepted for use with the SI units".

Ref: https://www.iau.org/static/resolutions/IAU2012_English.pdf, accessed 2022-12-17
Ref: https://www.bipm.org/documents/20126/41483022/SI-Brochure-9.pdf, accessed 2022-12-17


Please note, there is also the following lines from the NASA NAIF SPICE lib, but I leave without change here (@nasa should probably correct them upstream instead):

1 AU per the IAU 2012 Resolution B2 and the BIPM published "The International System of Units (SI), 9th ed."
Table 8 of "Non-SI units accepted for use with the SI units".

Ref: https://www.iau.org/static/resolutions/IAU2012_English.pdf, accessed 2022-12-17
Ref: https://www.bipm.org/documents/20126/41483022/SI-Brochure-9.pdf, accessed 2022-12-17
As per the XXVIII General Assembly of the International Astronomical Union, (2012 Resolution B).
And subsequent change by BIPM, the International Bureau of Weights and Measures, to the Non-SI units accepted for use with the SI units.

Also, added some explicit official references to the value provided.

(This commit here is effectively cherry-picked from what appeared to me to be the upstream libsgp4,
see its merge request dnwrnr/sgp4#31).
@NoNameForMee
Copy link
Copy Markdown
Author

@esa would anyone actually care to take a look at this MR?

In terms of unit conversions there is not really any more official source than "Bureau international des poids et mesures" (BIPM), i.e. the organisation behind the "International System of Units" (SI).

We all know that @nasa does not always properly enforce SI units all the way with all subsystem providers (e.g. NASA's Mars Climate Orbiter), but ESA should at least follow SI standard or??

(I have reached out to NASA NAIF team regarding the SPICE kernels incorrect AU conversion, but they have not yet updated SPICE for this, and it is perhaps not the highest priority...).

@darioizzo
Copy link
Copy Markdown
Member

We are using that number mainly for compatibility across tools, the user can change the value reassigning it. I am not sure we want to correct the value just now. Will keep this opened and monitor the cross compatibility situation ...

@NoNameForMee
Copy link
Copy Markdown
Author

We are using that number mainly for compatibility across tools, the user can change the value reassigning it. I am not sure we want to correct the value just now. Will keep this opened and monitor the cross compatibility situation ...

Ok, thanks for the clarification.

@darioizzo darioizzo closed this Mar 26, 2026
@darioizzo
Copy link
Copy Markdown
Member

closed as per pykep 3 new code base

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

2 participants