日の出・日の入り計算
任意の都市・座標・日付の日の出、日の入り、薄明、昼の長さを計算します。
結果
使い方
Search for a city (its coordinates and time zone fill in automatically) or type latitude and longitude directly, then pick a date. Times are shown in the location's own time zone.
標準的な天文計算式（NOAA）でローカルに計算します。緯度72°未満で誤差は約1分以内です。
よくある質問
What are civil, nautical and astronomical twilight?
They are stages of dawn and dusk defined by how far the sun sits below the horizon: civil twilight ends at 6°, nautical at 12°, astronomical at 18°. Civil twilight is when it is still bright enough for most outdoor activities; after astronomical dusk the sky is fully dark.
Why does the tool sometimes say the sun does not rise or set?
Above the polar circles the sun can stay up (midnight sun) or stay down (polar night) for weeks. On such dates there simply is no sunrise or sunset, and the tool says so instead of showing a misleading time.
How accurate are the times?
They are computed with the standard NOAA solar equations, which are typically accurate to within a minute for latitudes below about 72°. Atmospheric conditions can shift the observed moment slightly.