21st Century New and Full Moons

(2001-2030) - updated 2024-12-24

We are proud to present here the most accurate and precise listing of New and Full Moons for the 21^st Century (2001-2030). 

To our knowledge, this is the first and only such publication available to the public with millisecond and milliarcsecond accuracy and precision. JPL Horizons has the limitation of generating such results within 0.5 second intervals, so each event can only be calculated manually (at least until some programmer can create a specific algorithm) to achieve the desired result of 0.0000001" as the maximum difference in Ecliptic longitude between the Sun and Moon.  When this occurs (see highlights in snip), the Moon is applying to exactness in longitude whereas if we were to add a millisecond of time, it would cause a separation from exactness which is what we’ve avoided.  There are Horizons links included in the listing for the Sun and Moon results for researchers to compare our table with real-time data.

With the retrieval of this JPL Horizons data, we have available the other coordinates of RA, DEC, LAT, Galactic LON and LAT, km distance of the Moon with meter-level accuracy, the angular diameter of the Moon, type of eclipse (if any), SuperMoon status based upon a yearly qualifier, as well as Swiss Ephemeris (SE)-links to each event to compare their almost-accurate data with the gold-standard JPL Horizons. Here’s one PDF snip with most of the extra data:

Astrologers and astronomers will appreciate, we hope, the effort involved in this months-long, laborious project.  Those who do rectification of birth times are probably aware of how crucial it is to have accurate and precise transit data.  And, when casting any chart, in this case a New or Full Moon chart, one second of time is equivalent to approximately 15 arcseconds on an angle, and the slow movers like Pluto may spend several weeks, for example, near a station, traveling just an arcminute during those weeks!  To render a more accurate prediction of such a transit to an angle in any chart requires obviously more accurate timing, in this case of the New and Full Moon charts.

Every 1-3 days JPL Horizons updates the EOP coverage and predicts ahead (currently to 2025-03-20), so with each of their updates, with this kind of millisecond precision, the Moon calculation requires in almost all instances a subtraction of a millisecond in about a dozen or so of the future events so that the New or Full Moon is applying to 0.0000000 exactness. We could update our file with each of JPL’s update, and we’ve done a few, except lately, we’ve limited it to a monthly exercise. This needed subtraction is apparently due to the slight “movement or slowing down” of the Earth’s rotation that astronomers say began back in 2020 and is still continuing. For how long this slowing down will continue is anyone’s guess, though, and it might necessitate a leap second being subtracted next June or December 2025. That would be a first instance, however, since all others have been additions to the UTC time scale to agree with UT1 (formerly, GMT) which is rotational by definition, just as is sidereal time.

The more comprehensive or lengthier astrological tables from other sources, e.g., Astrodienst, AstroPixels, etc., are generally limited to one minute of time precision, which may cause up to more than 34 seconds divergence due to rounding errors, with which most astrologers don’t seem to be bothered. Both sources unfortunately use an outdated J. Meeus algorithm from last century to calculate their tables. Projected results with errors also due to their assumption that includes the addition of future leap seconds may also show up in the next decades of those tables.  Here’re three examples of New Moons that are more than 33 seconds off from the tabulation in both linked sources: 2028-06-22, 18:27:33.618 UT, 2029-10-07, 19:14:33.905 UT and 2030-01-04, 2:49:34.114 UT. Both lists show “18:27,” “19:14” and “2:49,” respectively, not rounded up, as one would expect. In other words, don’t use these tables to erect New or Full Moon charts if higher accuracy is of any concern, which was J. Meeus’ caveat.

In addition, it’s simply impossible to predict leap seconds, which is why JPL Horizons does NOT venture into vain prognostication beyond six months.  Mother Earth may just decide to continue over the course of weeks or months “slowing down” slightly more the rotation of the Cosmos around the GeoCenter, of which appears to most of us as the Earth speeding up instead.  If that continues, a leap second may, as mentioned, need to be subtracted for once, maybe twice, then the Cosmic rotation may speed up again (or, the Earth may “slow down,” if you will), who knows? There have been no leap seconds added since 2016, so stay tuned on that development.

For those who support our work, some of this data is available upon request, e.g., a particular year of tabulations, along with, of course, the full posts and additional content in the Celebrity Charts and Planetary Discoveries sections.