A clock aligned with the sun

True Solar Time

Your watch tells civil time — stitched to a time-zone, nudged by politics. The sun keeps its own time. This is where it is, right now, where you are.

True solar time at

Greenwich, United Kingdom(approximate, from your time zone)

08:32:04 PM

Sun now: −35.4° below; 291° W; under the horizon

Clock time08:15:35 PM (UTC+0)

Offset from clock+16m 29s

Equation of time

+16m 29s

axial tilt: +9m 50s
elliptical orbit: +6m 39s

Longitude correction

+0m 00s

vs. standard meridian UTC+0

Solar noon

11:43:31 AM

when the sun crosses your meridian

Sunrise

06:59 AM

Day length

9h 28m

Sunset

04:27 PM

Where are you?

Light through the year

Hours of daylight

How long the sun stays up each day at Greenwich, United Kingdom.

Longest day: Jun 21 · 16h 38m
Shortest day: Dec 21 · 7h 50m
Swing: 8h 48m

The sun's figure-eightShow the sun's yearly path

Next time your clock and the sun agree: Friday, December 25, 2026 (in 51 days)On that day the equation of time is zero. Only the longitude correction separates your clock from the sun.

Clock and sun agree in 2026

Apr15passed
Jun13passed
Sep1passed
Dec25next

The analemma

If you photographed the sun at the same clock time every day for a year, it would trace this exact shape in the sky. The horizontal axis is the equation of time — how far ahead or behind the sun is of your clock. The vertical axis is its declination — how far north or south it climbs. The small loop at the top is northern summer; the big loop at the bottom is northern winter, when Earth is closest to the sun and moves fastest.

The orange dot is where the sun stands today. The open circle marks the next day the curve crosses the centre line, when the equation of time is zero.

The formula

True solar time is simply your clock time, corrected for two things: where the sun actually is in its yearly dance, and where you stand within your time-zone.

True Solar Time
  = Local Clock Time
  + Equation of Time
  + Longitude Correction

Longitude Correction
  = 4 × (longitude − standard meridian)

Why bother?

Clock time is a convenience — a single number stretched across a whole slice of the planet. Your body, the plants, the birds, the rising light — none of them read a clock. They listen to the sun. Setting your rhythm by true solar time is a small act of returning to the real world.

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