Sunrise & Sunset Calculator
Sunrise (approx)
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Sunset (approx)
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Day Length
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Solar Noon
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How Sunrise and Sunset Are Calculated
Uses solar declination and hour angle equations. Declination varies +/-23.45 degrees with seasons, causing day length changes.
Hour angle formula: cos(HA) = -tan(latitude) x tan(declination). At extreme latitudes, the sun may not rise or set.
These are approximations. Actual times vary by a few minutes due to atmospheric refraction and longitude within timezone.
Frequently Asked Questions
Why do day lengths change?
Earth's 23.45 degree tilt causes the Sun's declination to change through the year.
Longest day of year?
Summer solstice (June 21 north, December 21 south). At 40 N, about 15 hours of daylight.
What causes midnight sun?
At latitudes above 66.5 degrees, the sun stays above the horizon for 24 hours near the solstice.
How accurate is this?
Within 5-10 minutes of actual times. Refraction, elevation, and orbital eccentricity are not included.