Equation of Time & Solar NoonMathematics

Equation of Time (EoT), Solar Noon & True Solar Time Astronomy Calculator

Calculate True Apparent Solar Time (AST), astronomical Solar Noon clock time, and the Equation of Time (EoT in minutes) accounting for Earth's orbital eccentricity and axial obliquity.

Calculator Inputs

Live Real-Time
day
Quick select:
deg
Quick select:
deg
Quick select:
Calculated ResultEquation of Time & Solar Noon

Solar Noon Clock Time (Decimal Hours)

11.91hrs

Equation of Time (EoT in Minutes)

-1.49 mins

Longitude Time Correction (Minutes)

6.8 mins

Total Solar Offset (Minutes)

5.31 mins

Astronomical Precision: Accurately computes true solar transit across the local geographical meridian.

Solar Time Profile

Equation of Time
-1.49 mins(0%)
Longitude Offset
6.8 mins(100%)

Detailed Calculation Breakdown

Longitude Offset
6.8 mins
Equation of Time
-1.49 mins
Solar Noon
11.91 hrs

Calculation Methodology

Equation of Time: EoT (mins) = 9.87*sin(2B) - 7.53*cos(B) - 1.5*sin(B), where B = 360/365*(Day - 81). Longitude Correction = 4 * (Local Longitude - Standard Meridian). Solar Time = Clock Time + Total Correction/60.

Important Legal & Educational Disclaimer

This celestial mechanics and astronomical geodesy tool calculates solar position kinematics.

This calculator is designed for educational and informational purposes only based on public statutory frameworks. The outputs do not constitute binding financial, tax, or legal advice. We assume no liability for decisions made based on these estimations. Always verify with the relevant official authorities or a certified professional advisor.

Frequently Asked Questions

Earth's 23.44° axial tilt (obliquity) combined with its slightly elliptical orbit (eccentricity), causing solar days to vary slightly throughout the calendar year.
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