Sun signs and the constellations they are named after divide the sky in two different ways, and in 2026 they seldom agree. We sampled every day of the year at noon Singapore time with the PyEphem 4.2.1 library, and the Sun stood in the constellation that shares its sign's name on 40 of 365 days. On 298 days it was in the previous sign's constellation. On 9 it was two signs back, and on 18 it was in Ophiuchus, which gives its name to no sign. A tropical sign is a 30° slice of the Sun's yearly path, counted from the March equinox. A constellation here is one of the official regions whose boundaries Eugène Delporte published in 1930, as Roman (1987) tabulates them.
Virgo lodges the Sun for more than 44 days, the longest stay of the year
We found each 2026 crossing to the second, then rounded to the hour: using the Sun's apparent position instead of its astrometric one moves a crossing by four to seven minutes.
| Sun enters | About, UTC+8 | Days |
|---|---|---|
| Capricornus | 20 Jan, 10:00 | 27.4 |
| Aquarius | 16 Feb, 21:00 | 24.1 |
| Pisces | 12 Mar, 22:00 | 37.5 |
| Aries | 19 Apr, 10:00 | 25.5 |
| Taurus | 14 May, 22:00 | 38.3 |
| Gemini | 22 Jun, 05:00 | 29.2 |
| Cancer | 21 Jul, 10:00 | 21.0 |
| Leo | 11 Aug, 09:00 | 37.1 |
| Virgo | 17 Sep, 10:00 | 44.5 |
| Libra | 31 Oct, 22:00 | 23.1 |
| Scorpius | 24 Nov, 01:00 | 6.5 |
| Ophiuchus | 30 Nov, 13:00 | 18.3 |
| Sagittarius | 18 Dec, 21:00 | 32.8* |
*The stay running into January 2027; the one that began in December 2025 was also 32.8 days. Two checks stand behind the table. Our own lookup over Roman's boundary list, catalogue VI/42 at the CDS VizieR service, reproduced every crossing within 50 seconds of PyEphem's boundary routine. A re-run of 2018 matched 12 of the 13 entry dates for that year in the table EarthSky published that January, which Bruce McClure drew from Guy Ottewell's Timetable of astronomical events. The one discrepancy was Capricornus. EarthSky gives 19 January, while our calculation places the crossing 47 minutes into 20 January UTC.
Ophiuchus hosts the Sun for almost three weeks
The Sun leaves Scorpius around 13:00 on 30 November 2026, Singapore time, and stays in Ophiuchus for 18.3 days, nearly three times its stay in Scorpius. Crossings drift by hours from year to year, so no fixed pair of dates holds every year.
Sign Aquarius begins at about 09:44 on 20 January, Singapore time, and the Sun crosses from Sagittarius into Capricornus less than half an hour later. For those minutes the sign is Aquarius while the Sun sits in Sagittarius, two names apart. In late October sign Scorpio has begun while the Sun is still in Virgo, which accounts for 8 of the 9 days two signs back. The ninth is 23 November, when sign Sagittarius has begun and the Sun is still in Libra.
Check-in comes about four weeks after a sign begins, on average
The main cause of the gap is precession, the slow turning of Earth's axis that carries the March equinox westward against the stars. In PyEphem's model the Sun at the March equinox stood at 27.80° of J2000 ecliptic longitude in AD 1 and at 359.64° in 2026, a shift of 28.16°. The Sun covers 360° in 365.2422 days on average, about 0.9856° a day, so on our arithmetic the shift is worth 28.6 days.
The measured gap fits. Across the 12 pairs of sign and namesake in 2026, the constellation entry comes on average 27.9 days after the sign begins. Run backwards, the equinox Sun crossed from the constellation Aries into Pisces in about 66 BC, and on the same model it reaches Aquarius in about 2600. Both are model years, the 1930 lines projected onto other centuries.
Uneven borders lengthen some stays and shorten others
Equal 30° constellations would give every sign roughly the same lag. The real regions are irregular: along the Sun's path their widths run from 6.5 days to 44.5. The lag therefore varies by sign, from 19.2 days for Leo to 38.6 days for Libra.
Against the 28.6-day precession figure, six signs lag less, Leo by the widest margin at 9.4 days short. Six lag more, and Libra runs furthest over, by 10.0 days. Precession sets the average at about four weeks; the uneven boundaries push individual signs around it, as many below as above.
Around the turn of the era the namesakes still turned the Sun away for two months
We repeated the count for every year from 200 BC to AD 200 and checked it with hourly samples. Measured hourly, agreement rises to a flat plateau of about 83% of the year, roughly 300 days, from roughly 60 BC to AD 75.
No single year stands out: noon samples reach 305 of 365 in four separate years, and neighbouring years differ by as much as six days, which is sampling noise. Even at the peak about two months a year disagreed, 18 or 19 of them in Ophiuchus. These figures rest on Delporte's 1930 boundaries projected backwards, so they describe our model of an ancient sky. Nobody had drawn those lines then.
The tropical signs open their doors at the equinox, whatever the stars
The signs were defined from the equinox to begin with. Ptolemy, writing in the 2nd century, says in Tetrabiblos I.10 that the zodiac has "no natural beginning", and he counts the signs from the vernal equinox, as he says earlier writers did (Robbins's 1940 translation, LacusCurtius). In a footnote, Robbins separates sign Aries, the 30° that begins at the equinox, from the constellation of that name.
A sign date is therefore a solar date, and it moves by hours each year, as our guide to why solar-term dates move explains. Our Sun Sign Finder works out each changeover from the Sun's computed position. Its 2026 times agree with PyEphem within 11 seconds, and across 2,400 changeovers from 1901 to 2100 the largest gap was 51 seconds, in December 2100. Until a revision dated 6 November 2026, its disclaimer still described a removed daily horoscope as "generated from the date", its zone list lacked UTC+6:30, Myanmar's offset in the IANA time zone database, and every birth defaulted to UTC+8. The revision drops that wording, adds +6:30 and Singapore's pre-war +7:20, and defaults to the offset Singapore kept on the birth date. In the revision, 21 March 1970 at 08:40 with the Singapore option gives Aries, because the Sun entered it at 08:26 local time; UTC+8 gives Pisces.
PyEphem and Roman's table re-run the guest list for any year
Each instant needs two lookups. Divide the Sun's apparent ecliptic longitude of date by 30° and round down for the tropical sign. Pass the Sun's astrometric J2000 position to constellation() in PyEphem, which needs no separate ephemeris file. Do both at noon each day and compare.
For an independent boundary test, Roman's VI/42 list gives each region's edges at the 1875 equinox, with a precession routine. For the sign side, the US Naval Observatory's Earth's Seasons service gives the 2026 March equinox as 14:46 UTC on 20 March, 22:46 in Singapore, the moment sign Aries begins.
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