Astronomical algorithms
by Jean Meeus · first published 1991
16mentions
8recommended by
15HN commenters
2010–2026first – last mentioned
53% recommend47% neutral
Why HN recommends it
Practical collection of recipes for positional astronomy, covering computations of planetary positions and ephemerides from formulas. Suited to hobby programmers and anyone converting the math into code.
Summarised by Claude from recommending comments
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To develop terminology and understanding of the physical/mathematical problems you could look into the books of Jean Meeus. "Astronomical Algorithms" contains, ...well, exactly that: small recipes to solve problems in positional astronomy or calculate ephemerides. Check Willman Bell publishers for the english version of his books. I liked "Celestial…
on “Ask HN: Celestial Mechanics Book Recommendations ” ↗For those of you interested in the topic, the best publicly available database I've found is http://www.astronexus.com/node/34, and The Book for astronomical computation is Astronomical Algorithms, by Jean Meeus, http://www.willbell.com/math/mc1.HTM (Shameless plug: I used both to implement the Common Lisp sky renderization engine for my startup, http://greaterskies.com, that makes pretty personalized…
on “100,000 stars” ↗It is a great fun to compute Planetary positions. You should really read a book named "Astronomical Algorithms" by Jean Meeus. That is the ultimate source for those computations, for hobby use. (There is a really nice chapter in there, about accuracy, and interpolation of values). You'll find various implementations…
on “Computing planetary positions – a tutorial with worked examples (2003)” ↗Astronomical Algorithms by Jean Meeus is a great read for anyone interested in these types of problems.
on “The Patek Philippe Caliber 89 and Horology’s Easter Problem” ↗Last time I looked into this I implemented some stuff from Astronomical Algorithms https://www.amazon.com/dp/0943396352 which was more fun for me than just grabbing the data.
on “Total Eclipse of the Moon: 2022 May 16” ↗I am currently trying to do (yet another) Rust implementation of the formulas in Jean Meeus' fantastic book "Astronomical Algorithms" (2nd ed. 1998). I am fighting two issues: 1. While it is possible to code the algorithms as a non-astronomer with the information provided in the book, I would definitely want to understand much better…
on “Ask HN: Which astronomy textbook for beginners?” ↗nice! I have needed this before. I think you're using the Meeus algorithm from Astronomical Algorithms? it's a classic, great choice
on “Show HN: Tiny Moon – Swift library to calculate the moon phase” ↗A book called "Astronomical Algorithms" was written back in the 80's or 90's. It was very exciting and inspirational for me that the sun and moon and the position of planets - nature itself - could be predicted by code. It still is an inspiration…
on “Ask HN: What piece of code/codebase blew your mind when you saw it?” ↗I've spent a lot of time finding objects in the sky to high accuracy with astronomical algorithms. The first step is always converting from UTC to TAI. See Astronomical Algorithms by Jean Meeus if you don't believe me. Your noon example works for a single longitude in a time zone and the time between…
on “Falsehoods programmers believe about Unix time” ↗A few months ago I submitted a link to Jean Meeus's Astronomical Algorithms (now available at https://shopatsky.com/products/astronomical-algorithms-2nd-e...) without realizing it was no longer available for purchase. Now the Willmann-Bell catalog is returning through Sky and…
on “Willmann-Bell Books Now Available” ↗Yes, pretty much every good library I came across referenced Meeus' Astronomical Algorithms [0] book and formulas. Those were a bit dense for me to fully parse, but Dr. Louis Strous` page [1] on finding the position of the moon helped simplify it for me (although that implementation is less…
on “Show HN: Tiny Moon – Swift library to calculate the moon phase” ↗I extracted the lunar calculations from my Android app Lunar Locator into a standalone Java library. The equations are from Jean Meeus' "Astronomical Algorithms." Given a time and location, it calculates relative lunar positions, rise/set times, distance, illumination, and more. Available on Maven Central (Java 17+): https://github.com/dgrims3/MoonLocatorLibrary…
on “Show HN: MoonLocator – Astronomical library for moon calculations in Java” ↗…needed) that calculates sun/shade exposure for every section at the World Cup 2026 stadiums depending on date and match time. The technical core: solar azimuth and altitude calculations (based on Meeus astronomical algorithms, ~0.3 degree accuracy) tied to each stadium's orientation and GPS coordinates. For each open-air stadium I mapped the seating sections to compass bearings, then render an interactive overlay showing which…
on “Show HN: I calculated sun/shade exposure for every seat at World Cup stadiums” ↗It uses the Python lib Astral, which uses "equations from Astronomical Algorithms, by Jean Meeus", to find location of the Sun in the sky. That method assuming earth motion without gravitational pull from other planets or the Moon, and has accuracy of 0.01 arc degree. Meeus is a rock…
on “Hengefinder: Finding When the Sun Aligns with Your Street” ↗…based on Astronomy Answers articles that are thankfully still live at https://www.aa.quae.nl/en/reken/zonpositie.html, but v2.0 specifically was rewritten to use the approach described in Jean Meeus' Astronomical Algorithms book.
on “Sun Clock” ↗