What is solar noon and why does it differ from 12:00?

Solar noon is the moment the sun crosses the local meridian and reaches its highest point in the sky. It rarely coincides with 12:00 on your clock because clocks are set to a fixed time-zone offset, while the sun moves continuously. Two corrections shift it - the equation of time (up to plus or minus 16 minutes, caused by the elliptical orbit and axial tilt) and the longitude difference between your location and the centre of your time zone (4 minutes per degree).

How accurate is the solar noon time given by this calculator?

The calculator uses the NOAA solar position algorithm, based on Meeus (Astronomical Algorithms, 2nd edition). For dates between 1900 and 2100 the error is within about 1 minute of arc for the sun angle and within about 1 minute of time for noon and sunrise/sunset. Atmospheric refraction at the horizon adds a small additional uncertainty of around 1-2 minutes depending on weather.

What is the equation of time?

The equation of time is the difference (in minutes) between apparent solar time and mean solar time. It arises because Earth moves faster when near perihelion (January) and slower near aphelion (July), and because the ecliptic is tilted relative to the equator. The combined effect produces a figure-eight analemma pattern - the sun can be up to 16 minutes ahead of or behind clock noon over the course of a year.

How is the golden hour calculated?

The golden hour is defined as the period when the sun is between 0 degrees and 6 degrees above the horizon. The calculator finds the hour angle at which the solar elevation equals exactly 6 degrees using the same spherical trigonometry as the sunrise/sunset calculation, then converts that hour angle to a local time. The morning golden hour runs from sunrise until that time; the evening golden hour runs from that time until sunset.

What happens at polar latitudes?

Above the Arctic Circle or below the Antarctic Circle the sun can remain continuously above or below the horizon for days or months around the solstices. When the sun never sets the calculator shows polar day and still reports solar noon and elevation. When the sun never rises it shows polar night and only the equation of time and declination are meaningful.

Does this calculator account for daylight saving time?

The UTC offset field is purely manual. Enter the actual offset in effect on the chosen date - for example +2 for British Summer Time or +1 for Central European Standard Time. The calculator has no knowledge of DST transition rules, so you must apply the correct offset yourself.

Solar Noon Calculator

The Solar Noon Calculator tells you the exact local time when the sun is at its highest point in the sky for any location and date on Earth — plus sunrise, sunset, day length, golden hour windows and the solar elevation angle. Everything runs entirely in your browser using the NOAA solar position algorithm (Jean Meeus, Astronomical Algorithms); no data is ever sent to a server.

Why solar noon matters

Solar noon is the anchor point of the solar day. It is the moment the sun crosses your meridian, casts the shortest shadow, and shines with maximum intensity. Knowing it matters for:

Photographers — golden hour (that warm, low-angle light) starts at sunrise and ends roughly when the sun reaches 6° elevation; it mirrors symmetrically around solar noon in the evening.
Solar panel owners — panels produce the most electricity in the hour or two each side of solar noon, so pointing them true south (in the northern hemisphere) toward the solar-noon azimuth maximises yield.
Gardeners and architects — shadows are shortest at solar noon; knowing the solar elevation tells you how long a shadow any vertical object will cast.
Astronomers and navigators — the ancient technique of finding true north by bisecting the angle between a shadow at sunrise and at sunset requires knowing which moment falls exactly halfway between — solar noon.

How it works

The calculator derives every figure from first principles using four main quantities:

1. Julian Day Number (JD) — a continuous count of days since 4713 BC, used to remove calendar irregularities from the arithmetic.

2. Solar declination — the angle between the sun and the equatorial plane, ranging from −23.45° (winter solstice) through 0° (equinoxes) to +23.45° (summer solstice). On any given day, declination tells us how far north or south the sun rises and sets.

3. Equation of time (EqT) — the difference in minutes between the sun on your clock and the true sun in the sky. It is derived from the eccentricity of Earth’s orbit and the tilt of the ecliptic, and varies between about −16 and +14 minutes over a year.

4. Hour angle at sunrise/sunset — found by solving the spherical-trigonometry equation for the zenith angle of 90.833° (which accounts for atmospheric refraction and the apparent radius of the solar disc):

cos(HA) = (cos(90.833°) − sin(lat) · sin(dec)) / (cos(lat) · cos(dec))

Solar noon in UTC hours is:

Solar noon UTC = 12 − EqT / 60 − longitude / 15

Converting to local time adds your UTC offset. Sunrise is noon − HA/15 hours; sunset is noon + HA/15 hours.

Worked example — London on 21 June (summer solstice)

Latitude 51.51° N, Longitude −0.13° E, UTC +1 (BST)
Declination ≈ +23.44° (sun at its most northerly)
Equation of time ≈ −1.7 min (clocks run about 2 min ahead of the sun)
Solar noon UTC ≈ 12 − (−1.7/60) − (−0.13/15) ≈ 12:01 UTC → 13:01 BST
Sunrise ≈ 04:43 BST, Sunset ≈ 21:21 BST
Day length ≈ 16 h 38 m
Solar elevation at noon ≈ 90° − (51.51° − 23.44°) = 61.9°
Morning golden hour ends around 06:00 BST; evening starts around 20:04 BST

Compare this to 21 December: day length shrinks to about 7 h 50 m and the midday sun only reaches about 15° — less than a quarter of the way up the sky.

Formula reference

Quantity	Formula (simplified)
Solar noon (UTC h)	12 − EqT/60 − lon/15
Elevation at noon	arcsin(sin(lat)·sin(dec) + cos(lat)·cos(dec))
Sunrise offset (h)	arccos((cos(90.833°) − sin(lat)·sin(dec)) / (cos(lat)·cos(dec))) / 15
Golden-hour offset (h)	arccos((cos(84°) − sin(lat)·sin(dec)) / (cos(lat)·cos(dec))) / 15

All angles in the formulas above are in degrees; the calculator converts to radians internally before calling trigonometric functions.