実用

Sunset Time Calculator

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Times shown in UTC. For your local time, add your timezone offset. Approximation — actual times may differ by a few minutes.

Sunrise & Sunset Calculator

Latitude

+ North, − South

Longitude

+ East, − West

Date

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Detailed Guide Coming Soon

We're working on a comprehensive educational guide for the Sunset Time Calculator in your language. The content below is shown in English.

とは何か Sunset Time Calculator?

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A sunset calculator computes the exact time of sunset and civil twilight for any location and date using solar position algorithms.

Calkulon makes complex calculations simple — built for students and everyday problem-solvers.

公式

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f(x)Sunset time depends on latitude, longitude, date, and refraction. Uses NOAA algorithm or lookup tables.

変数の説明

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記号	名前	単位	説明
φ	Latitude	degrees	—
λ	Longitude	degrees	—
t	Sunset time	local time (HH:MM)	—

方法 Sunset Time Calculator

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1Based on solar declination, hour angle, and observer latitude/longitude
2Civil twilight ends when sun is 6° below horizon
3Nautical twilight: 12°; Astronomical twilight: 18°
4Equation of Time accounts for Earth's elliptical orbit

解いた例

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例 1

入力:London (51.5°N), 21 December 2025

結果:Sunset ≈ 15:58 GMT; Civil twilight ends ≈ 16:32 GMT

実際の応用

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Photography planning (golden hour)

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Outdoor event scheduling

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Safety and security lighting

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Astronomical observation times

London Sunset Times by Season

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Date	Sunset (BST/GMT)	Day length
21 Jun (summer)	21:21 BST	16h 38min
23 Sep (equinox)	19:01 BST	~12h
21 Dec (winter)	15:58 GMT	7h 56min
20 Mar (equinox)	18:16 GMT	~12h

よくある質問

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Why does sunset time change throughout the year?

Earth's axial tilt. Summer: sun higher arc, sets later. Winter: sun lower arc, sets earlier.

Is sunset time the same everywhere?

No. Latitude determines sun angle. Longitude determines time zone. Terrain (hills, mountains) can block sun.

What's the difference between sunset and twilight?

Sunset: sun touches horizon. Civil twilight: 6° below horizon (still light). Nautical: 12° below (navigational).

参考文献

›Sunrise/sunset — NOAA

Formula-verified for precision

Reviewed October 2026

Our methodology

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