<p>The methods described in Jean Meeus's book are still valid, and accurate enough for the needs of most amateur and many professional astronomers.  The science of positional astronomy doesn't change so rapidly that a book published in 1991 would be out of date only 30 years later.  Even methods developed in the 19th century, such as Besselian elements of eclipses, are still useful in the 21st century.</p>
<p>Having said that, better solar system ephemerides do appear from time to time, such as the newer ones from IMCCE which supersede VSOP87.  In my own code (written in Java and available at GitHub: <a href="https://github.com/DavidHarper/astrojava" rel="nofollow noreferrer">https://github.com/DavidHarper/astrojava</a>) I prefer to use the JPL Development Ephemeris representations of the orbits of the Moon and planets, because they are computationally easier to use than the IMCCE representations.  However, I don't criticise Meeus (or anyone else) for choosing VSOP87.</p>

CC BY-SA 4.0
2024-02-21T06:46:09.323Z
*Welcome to Stack Exchange!* Are these the "newer ones from IMCCE"? https://www.imcce.fr/services/ephemerides/ If so perhaps you an add this link to your post. *Thanks!*
uhoh
CC BY-SA 4.0
2024-02-21T06:51:11.033Z
random factoid; while [PyEphem and XEphem are based on VSOP87](https://stackoverflow.com/q/34487170/3904031) the newer Python package [Skyfield](https://rhodesmill.org/skyfield/) imports the JPL DE that the user specifies, plus Keplerian orbital elements for minor planets and comets not represented in the DEs.
uhoh
CC BY-SA 4.0
2024-02-21T07:00:13.070Z
Sorry for so many comments; just fyi there are [almost 200 Stack Exchange sites](https://stackexchange.com/sites#percentanswered) and these include [Space Exploration SE](https://space.stackexchange.com/), [retrocomputing SE](https://retrocomputing.stackexchange.com/) and [Super User](https://superuser.com/).
uhoh
CC BY-SA 4.0
2024-12-24T00:34:22.703Z
Meeus' work is dated for a number of reasons. 
1.  The IAU has made multiple changes to the standard quantities used in these calculations.
2. Meeus himself does not follow IAU standards
3. GAIA and other star mappings have caused many changes to the Earth Reference Frames.
4. Meeus's limitations are reflected as computational power in the 90s was still pretty low.  in 2024, our computational power has increased by multiple factors that make calculating VSOP87 trivial.
5. Laser Imaging from JPL and DE441 have made ephemeris calculations much more rigorous.
Danny F
CC BY-SA 4.0
2024-12-24T00:40:10.877Z
Working through the literature, even Laskar's seminal works on precession quantities etc. show that in the space of 40 years, much has improved, and we can make much more accurate, detailed analysis for the range -13000 to +17000 years.
Add to that Meeus' calculations are limited in scope to 1600-2050 make everything about his work useless for historical data.
Danny F
CC BY-SA 4.0
2024-12-24T00:46:52.590Z
Basic calculations like precession have vastly new equations utilizing IAU2006A and IAU2006B - admitedly the number of terms is astronomical! but these are easily available via ftp.  It would be nice to have everything upgraded to VSOP2013 and MPP02. (considering that ELP2000's authors themselves admit to a better semi-analytical model)
Danny F
CC BY-SA 4.0
2024-12-24T00:51:26.937Z
Also infuriating is the way dating and julian day numbering is handled in Meeus' work.  Works such as Dershowitz and Reingold's Calendarical Calculations (https://www.amazon.com/Calendrical-Calculations-Ultimate-Edward-Reingold/dp/1107683165) , Ultimate Edition offer more robust and consistent solutions.  It is obvious that Meeus is not a computer programmer and this shows in the book in the handling of radians vs. degrees.  His solutions are elegant and do take into account the computational power of a microcomputer.  Today, our phones have more computational power.
Danny F
CC BY-SA 4.0
2024-12-25T07:11:39.843Z
Whilst Danny F's comments about newer IAU standards, precession models and ephemerides are true, I would re-iterate my earlier comment. For most users, including many professional astronomers, Meeus's methods give perfectly good results.
DavidHarper
CC BY-SA 4.0
2024-12-25T07:11:50.370Z
If you're actively involved in high-precision astrometry missions such as Gaia, or navigating a multi-billion-dollar spacecraft such as Parker Solar Probe, or measuring continental drift using a research-grade GPS system, then yes, you'll definitely want to use the latest and best solar system ephemerides, Earth rotation models and so forth.  But if you're doing any of those things, then you're very unlikely to be consulting StackExchange for advice :-)
DavidHarper
CC BY-SA 4.0
2024-02-21T06:27:01.597Z
2024-02-21T06:27:01.597Z
DavidHarper
<p>I understand that the <a href="https://rads.stackoverflow.com/amzn/click/com/0943396611" rel="nofollow noreferrer" rel="nofollow noreferrer">Meeus book</a> is a classic in astronomical calculations. I've read through many chapters of it now and while the content is great, it'd be nice to have discussion based on more recent context.</p>
<p>Is there a &quot;modern equivalent&quot; to this classic book?</p>

CC BY-SA 4.0
2023-06-13T06:11:06.553Z
If there is one, I would also like to know about it! I think it remains the only work of its kind, though. Updated quantities have been published here and there, but not in a single work. For example, for the Moon’s orbit, one can refer to Éphémérides Lunaires Parisiennes; for the planets, to VSOP 2013; etc.
Pierre Paquette
CC BY-SA 4.0
2023-06-13T17:58:58.147Z
The amazon comments seem to have suggestions.. Also observe that the author is long-dead, the work is therefore copyright free and I don't see how amazon can charge 100$ for this.. ridiculous capitalism.
AtmosphericPrisonEscape
CC BY-SA 4.0
2023-06-13T19:05:09.530Z
@AtmosphericPrisonEscape Supply was disrupted when Willmann-Bell went out of business. Sky Publishing now [sells it for $36](https://shopatsky.com/products/astronomical-algorithms-2nd-edition). Copyright endures several decades after publication or author's death depending on country.
Mike G
CC BY-SA 4.0
2023-06-13T19:16:11.920Z
@MikeG Ah, I was under the impression that he is already dead for a century..
AtmosphericPrisonEscape
CC BY-SA 4.0
2023-06-13T20:06:25.570Z
He is still alive. https://en.wikipedia.org/wiki/Jean_Meeus *Astronomical Algorithms* was first published in 1991.
PM 2Ring
CC BY-SA 4.0
2023-06-13T20:23:22.883Z
@MikeG That's probably good enough to be converted to an answer, along with the detail that the author is still alive.
StephenG - Help Ukraine
CC BY-SA 4.0
2023-06-13T20:42:44.340Z
The closest thing to an updated version is the Explanatory Supplement to the Astronomical Almanac, 3rd ed, but it is not aimed at amateurs.
Greg Miller
<algorithm>
Modern equivalent of Astronomical Algorithms by Jean Meeus?
Ana
# Modern equivalent of Astronomical Algorithms by Jean Meeus?

(Asked by: username_0 on 2023-06-13)

I understand that the [Meeus book](https://rads.stackoverflow.com/amzn/click/com/0943396611) is a classic in astronomical calculations. I've read through many chapters of it now and while the content is great, it'd be nice to have discussion based on more recent context.

Is there a "modern equivalent" to this classic book?

**Tags:** algorithm
> **Comments:**
> **username_1**: If there is one, I would also like to know about it! I think it remains the only work of its kind, though. Updated quantities have been published here and there, but not in a single work. For example, for the Moon’s orbit, one can refer to Éphémérides Lunaires Parisiennes; for the planets, to VSOP 2013; etc.  
> **username_2**: The amazon comments seem to have suggestions.. Also observe that the author is long-dead, the work is therefore copyright free and I don't see how amazon can charge 100$ for this.. ridiculous capitalism.  
> **username_3**: @AtmosphericPrisonEscape Supply was disrupted when Willmann-Bell went out of business. Sky Publishing now [sells it for $36](https://shopatsky.com/products/astronomical-algorithms-2nd-edition). Copyright endures several decades after publication or author's death depending on country.  
> **username_2**: @MikeG Ah, I was under the impression that he is already dead for a century..  
> **username_4**: He is still alive. https://en.wikipedia.org/wiki/Jean_Meeus *Astronomical Algorithms* was first published in 1991.  
> **username_5**: @MikeG That's probably good enough to be converted to an answer, along with the detail that the author is still alive.  
> **username_6**: The closest thing to an updated version is the Explanatory Supplement to the Astronomical Almanac, 3rd ed, but it is not aimed at amateurs.  

---

## 1 answers

### Answer by username_7 on 2024-02-21. Score: 3

The methods described in Jean Meeus's book are still valid, and accurate enough for the needs of most amateur and many professional astronomers. The science of positional astronomy doesn't change so rapidly that a book published in 1991 would be out of date only 30 years later. Even methods developed in the 19th century, such as Besselian elements of eclipses, are still useful in the 21st century.

Having said that, better solar system ephemerides do appear from time to time, such as the newer ones from IMCCE which supersede VSOP87. In my own code (written in Java and available at GitHub: <https://github.com/DavidHarper/astrojava>) I prefer to use the JPL Development Ephemeris representations of the orbits of the Moon and planets, because they are computationally easier to use than the IMCCE representations. However, I don't criticise Meeus (or anyone else) for choosing VSOP87.

> **Comments:**
> **username_8**: *Welcome to Stack Exchange!* Are these the "newer ones from IMCCE"? https://www.imcce.fr/services/ephemerides/ If so perhaps you an add this link to your post. *Thanks!*  
> **username_8**: random factoid; while [PyEphem and XEphem are based on VSOP87](https://stackoverflow.com/q/34487170/3904031) the newer Python package [Skyfield](https://rhodesmill.org/skyfield/) imports the JPL DE that the user specifies, plus Keplerian orbital elements for minor planets and comets not represented in the DEs.  
> **username_8**: Sorry for so many comments; just fyi there are [almost 200 Stack Exchange sites](https://stackexchange.com/sites#percentanswered) and these include [Space Exploration SE](https://space.stackexchange.com/), [retrocomputing SE](https://retrocomputing.stackexchange.com/) and [Super User](https://superuser.com/).  
> **username_9**: Meeus' work is dated for a number of reasons.  1.  The IAU has made multiple changes to the standard quantities used in these calculations. 2. Meeus himself does not follow IAU standards 3. GAIA and other star mappings have caused many changes to the Earth Reference Frames. 4. Meeus's limitations are reflected as computational power in the 90s was still pretty low.  in 2024, our computational power has increased by multiple factors that make calculating VSOP87 trivial. 5. Laser Imaging from JPL and DE441 have made ephemeris calculations much more rigorous.  
> **username_9**: Working through the literature, even Laskar's seminal works on precession quantities etc. show that in the space of 40 years, much has improved, and we can make much more accurate, detailed analysis for the range -13000 to +17000 years. Add to that Meeus' calculations are limited in scope to 1600-2050 make everything about his work useless for historical data.  
> **username_9**: Basic calculations like precession have vastly new equations utilizing IAU2006A and IAU2006B - admitedly the number of terms is astronomical! but these are easily available via ftp.  It would be nice to have everything upgraded to VSOP2013 and MPP02. (considering that ELP2000's authors themselves admit to a better semi-analytical model)  
> **username_9**: Also infuriating is the way dating and julian day numbering is handled in Meeus' work.  Works such as Dershowitz and Reingold's Calendarical Calculations (https://www.amazon.com/Calendrical-Calculations-Ultimate-Edward-Reingold/dp/1107683165) , Ultimate Edition offer more robust and consistent solutions.  It is obvious that Meeus is not a computer programmer and this shows in the book in the handling of radians vs. degrees.  His solutions are elegant and do take into account the computational power of a microcomputer.  Today, our phones have more computational power.  
> **username_7**: Whilst Danny F's comments about newer IAU standards, precession models and ephemerides are true, I would re-iterate my earlier comment. For most users, including many professional astronomers, Meeus's methods give perfectly good results.  
> **username_7**: If you're actively involved in high-precision astrometry missions such as Gaia, or navigating a multi-billion-dollar spacecraft such as Parker Solar Probe, or measuring continental drift using a research-grade GPS system, then yes, you'll definitely want to use the latest and best solar system ephemerides, Earth rotation models and so forth.  But if you're doing any of those things, then you're very unlikely to be consulting StackExchange for advice :-)  

---

