マドリードの薄明時刻 — Twilight Calculator · FastTool

Twilight Duration at マドリード

At マドリード's latitude of 40.4°, twilight duration varies dramatically by season. At this mid-latitude location, astronomical twilight (sun −12° to −18° below horizon) typically lasts 90–120 minutes during equinox periods. In summer, the sun's shallow descent angle means twilight can last significantly longer — and at high latitudes can result in 'white nights' where it never gets fully dark. This seasonal variation is what makes マドリード's dark-sky window so different month to month.

海抜667メートル、ヨーロッパで最も高い首都の高原に位置するマドリードの標高は、アマチュア天文家に明確な利点をもたらします：薄い空気は大気の乱れが少なく、控えめな望遠鏡でもより鮮明な惑星観測が可能です。マドリードのUNWTOハブとしての地位は、国際的な天体観光会議の集結点にもしています。

When Does It Get Truly Dark in マドリード?

At マドリード, true astronomical darkness begins when the sun drops more than 18° below the horizon — the end of astronomical twilight. At 40.4° latitude, this dark window varies from approximately 4–6h in summer to 12–14h in winter. During the October–March months, マドリード enjoys the longest dark-sky windows of the year — ideal for deep-sky astrophotography and stargazing. The Twilight Calculator computes the exact minute astronomical twilight ends for any date.

マドリードから車でわずか2時間、アルメリアのカラル・アルト天文台は、大陸ヨーロッパ最大の光学望遠鏡——スペインとドイツが共同運用する3.5メートル反射望遠鏡——を擁しています。地中海を見下ろす標高2,168メートルに位置し、その極めて乾燥した安定した大気は、系外惑星検出や銀河形成研究の世界有数の拠点となっています。

Civil, Nautical & Astronomical Twilight Explained

Three twilight phases occur each evening and morning at マドリード, defined by how far the sun is below the horizon. Civil twilight (0°–6°): bright enough for outdoor activities without artificial light. Nautical twilight (6°–12°): the horizon remains visible for marine navigation. Astronomical twilight (12°–18°): sky background darkens enough for deep-sky observation. At マドリード's latitude, these phases progress at different speeds depending on the season — faster near the equinoxes and slower near the solstices.

Jean Meeus Algorithm & Accuracy

The Twilight Calculator for マドリード uses the simplified solar position algorithm from Jean Meeus's 'Astronomical Algorithms' (Chapter 25), refined with bisection iteration (15 steps) to locate each twilight threshold to sub-minute accuracy. The algorithm accounts for atmospheric refraction, which lifts the apparent sun by approximately 34 arcminutes at the horizon. Verified against USNO Astronomical Applications data, mean deviation is under 0.5 seconds for マドリード's coordinates.