Solar Return Date: Only the Timing, Not a Solar Return Chart

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This page explains one thing: the date and time at which the Sun returns to the exact longitude it had at your birth, and why that moment can fall on a different date, or at a different clock time, from your birthday. It does not cast a solar return chart, does not relocate one and does not interpret one. Houses, an Ascendant, aspects or any forecasting technique for that moment are not covered here and are outside this site's method.

The short answer is that the Sun's return is set by astronomy and your birthday is set by the calendar, and the two run at slightly different rates. For one invented birth, measured over thirty years:

• Exactly one return a year. The Sun reached the natal Sun degree once in each of the thirty years from 2000 to 2029, always moving forward, never twice and never backward.
• Usually on the birthday, sometimes the day before. In Brussels clock time, 25 of the 30 returns fell on 15 August, the birthday, and 5 fell on 14 August.
• Rarely at the birth time. The local clock time of the return ran from 13 hours 49 minutes before 10:20 to 9 hours 22 minutes after it.
• A four-step rhythm. In years without a 29 February in between, the return came about 5 hours 48 minutes later on the clock than the year before; across a 29 February it came about 18 hours 12 minutes earlier.

Educational page. Astrologist.com has no transit or return tool: there is no solar return calculator, transit calendar or timing report here. The free birth chart shows natal positions only, and every date below was computed offline for an invented person.

The birth and the rules

The person is the invented Antwerp birth already used on Mars Return and Mars transits to natal Sun, reused unchanged. Window and method were settled before the first return was solved.

• Birth: 10:20 on 15 August 1989 in Antwerp. Belgian summer time (UT+2) applied, so the instant is 08:20 UT.
• Natal Sun: unrounded 142.488317°, which is 22°29'17.9" Leo, moving 0.961° a day. The chart stores 142.49° and shows 22°29' Leo. The unrounded value is the target throughout.
• Window: every return whose UT instant falls from 1 January 2000, 00:00 UT, up to but not including 1 January 2030, 00:00 UT.
• Method: the Sun's longitude comes from the very routine the chart uses (the astronomia package's apparent solar longitude), with Universal Time converted to ephemeris time in the same way. Each return was found from a six-hourly scan and then solved directly by bisection to well under a second. That is a solver tolerance; how close the model itself is to the real Sun is a separate question, treated further down. Brussels clock times were produced with the same time-zone rules the chart uses and checked back through the chart's own local-to-UT conversion. Times are UT unless marked as Brussels time, and returns after October 2026 are model projections.

Comparison rule. Each return's Brussels clock time is compared with 10:20 on 15 August of the same year, also on the Brussels clock, and the difference is given with a sign: minus means the return came earlier than that birthday clock time, plus means later. Times are cut to the minute, with seconds dropped.

Every return from 2000 to 2029

Every return fell in Belgian summer time, as the birth did, so the clock change never entered the comparison here. Returns from 2027 to 2029 are model projections.

One crossing per year, checked rather than assumed. A six-hourly scan of the Sun's distance from the natal degree found 30 forward crossings in the window, and a separate hourly scan found no backward crossing at all. The Sun does not loop backward the way the planets do, so in a Tropical zodiac it can reach a given degree only once per lap. The returns either side of the window, on 15 August 1999 at 18:29 UT and 15 August 2030 at 06:07 UT, lie well clear of its edges.

The astronomy: how long a "solar year" took here

From one return to the next took between 365.24003 and 365.24336 days, an average of 365.24137 days. Two things stand out.

First, every gap is about a quarter of a day longer than a 365-day calendar year, and about 0.009 days, or roughly 12 minutes, shorter than the 365.25-day average the calendar keeps between 2000 and 2029, when every fourth year has a 29 February.

Second, the gaps were not all equal. They varied by about 4.8 minutes from shortest to longest. A straight line through the thirty return times leaves the individual returns between 8.0 minutes early and 7.7 minutes late. The Earth's orbit is not perfectly regular, so the Sun's apparent motion speeds up and slows down very slightly from year to year; this is a property of the astronomy, not of clocks or calendars.

The civil time: why the clock and the date move

With the astronomy in hand, the clock pattern in the table follows from the calendar:

• Common years push the time later. Between two returns with no 29 February in between, the Brussels clock time moved later by 5 hours 46 minutes to 5 hours 50 minutes, because the return interval is about a quarter day longer than 365 days.
• A 29 February pulls it back. Across each 29 February from 2004 to 2028, the clock time moved earlier by 18 hours 10 minutes to 18 hours 14 minutes: one whole extra calendar day, less that quarter day.
• The cycle does not quite close. Because four calendar years average 365.25 days and the returns here averaged 365.24137, the same point in the leap cycle drifts earlier over time: 8 hours 1 minute before 10:20 in 2000, but 13 hours 49 minutes before it in 2028. The 2028 return is a model projection.
• The date follows the clock. When the time is pushed far enough back, the return slips to the day before. Here that happened five times, each time in a leap year: 2012, 2016, 2020, 2024 and 2028, all on 14 August in Brussels.
• UT and local dates can differ. In 2004 and 2008 the return was on 14 August in UT but already 15 August on the Brussels clock, two hours ahead. Anyone reading a UT table needs to convert before comparing with a birthday.

So leap years are one cause of the date change, but not the only one. The clock reading also depends on the zone and on whether summer time applies, and the small year-to-year variation in the astronomy shifts each return by minutes. For a birth near a clock-change weekend in late March or late October, the summer time status at birth and at the return might not match; that check belongs to the conversion, as explained in birth time, time zones and daylight saving.

The return is a single instant for the whole world. Someone living in another zone reads that same instant on a different clock; nothing about the Sun's position changes, and this page does not set up a chart for wherever that person lives.

If the birth time is unknown

Without a birth time, natal Sun is not one value but a range. The whole Antwerp birth date runs from 22:00 UT on 14 August up to, but not including, 22:00 UT on 15 August 1989. Across that day the Sun moved from 142.074636° (22°04'28.7" Leo) at 00:00 local time to a limiting value of 143.035542° (23°02'08.0" Leo) at 24:00, a span of 0.961°. The value at 23:59 was 143.034874°, about a minute's worth of motion short of the 24:00 limit, which belongs to the next date.

Solving the return for both ends of that range gives, in each year, a span of return instants a little over 24 hours wide (24.002 to 24.006 hours). For example:

So for an unknown time, the honest answer is a window of about a day that can straddle two calendar dates. As a separate check, the 2026 return was worked out for 145 sample birth times (every ten minutes from 00:00 to 23:50, plus 23:59); the sampled returns all fell on 14 or 15 August on the Brussels clock. Those are samples, not a proof of limits.

Rounding, and a second ephemeris

Using the stored 142.49° instead of the unrounded value made every return 2.52 minutes later. Reading the displayed 22°29' Leo back as 142.4833° made every return 7.47 minutes earlier. Neither moved any return to another Brussels date. The displayed minute stands for a range of values, so a displayed position cannot pin the return to better than several minutes.

The Swiss Ephemeris, an independent ephemeris, was used only as a reference. It places the natal Sun 5.33 arc-seconds below the chart's value. At the chart's thirty return instants, Swiss put the Sun up to 25.9 arc-seconds away from the target, and solving each return again with the Swiss Sun moved it by up to 10.8 minutes (8.6 minutes when the Swiss natal Sun is used as the target too). The solver's sub-second tolerance is therefore no guide to the model's accuracy: read the minutes in the table as this model's minutes, which another ephemeris can move by several. The repository's golden fixtures, which cover the Sun, test chart positions to 0.05°; they are chart checks, not return-time accuracy figures.

Using the date, if you want to

Some people like to mark the moment the Sun gets back to its natal degree as a personal new year, a pause to look at natal Sun's sign and what it describes. That is an optional reflection: the return causes nothing, predicts nothing and explains no event, and nothing here is a claim about health, money, work, relationships or any other outcome.

Working out your own date

1. Read natal Sun from the free birth chart and write it as a longitude from 0° Aries. A displayed minute is a small range, not an exact value.
2. In a Tropical ephemeris, find for each year the moment the Sun passes that longitude; it happens once a year, within about a day of your birthday.
3. Convert that UT moment to the clock of the place you care about, using that place's time-zone and summer time rules for that date.
4. Compare it with your birthday date and birth time on the same clock. Expect the time to move later by roughly six hours a year and to jump back after each 29 February.
5. If your birth time is unknown, solve for the start and the end of your birth date; your return is somewhere in that span of about a day.

A manual method is in how to read transits without a transit tool. For how Venus, which does loop backward, comes back to its own natal degree, see Venus Return. Ask the Astrologist can talk about natal Sun or about a return date you have found yourself; it does not compute return dates.

Related articles

• Venus Return (a planet that can loop back over its natal degree)
• Mars Return
• Birth Time, Time Zones and Daylight Saving
• Mars Transits to Natal Sun (a different mover, the same natal Sun)
• Jupiter Transits to Natal Sun
• Birth Chart Without a Birth Time
• Reading Transits Without a Tool
• Lunar Return Date (the Moon back on its natal degree, about thirteen times a year)
• Sun Transits Through the Houses (the same yearly solar lap, measured against natal house cusps)