台北の薄明時刻 — Twilight Calculator · FastTool

Twilight Duration at 台北

At 台北's latitude of 25.0°, 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 台北's dark-sky window so different month to month.

台北は北緯25度の北回帰線近くに位置し、夏至には太陽が正確に高度90°に達し、正午に影がなくなる緯度です。市立自然科学博物館は太陽の天頂通過を追跡する専用の太陽観測所を運営しており、嘉義の北回帰線標識は毎年6月に「無影日」現象を目撃しようと数千人の訪問者を集めます。

When Does It Get Truly Dark in 台北?

At 台北, true astronomical darkness begins when the sun drops more than 18° below the horizon — the end of astronomical twilight. At 25.0° latitude, this dark window varies from approximately 4–6h in summer to 12–14h in winter. During the October–March months, 台北 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.

北緯25度の台北では、夏と冬の日照時間差は約3.5時間と、東アジアの首都の中で最も小さくなります。この赤道への近さは、ゴールデンアワーが高緯度地域よりも年間を通じて安定していることを意味し、太陽がより急な角度で昇り沈むため、台北の狭い路地文化に鮮明で劇的な影を落とします。

Civil, Nautical & Astronomical Twilight Explained

Three twilight phases occur each evening and morning at 台北, 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 台北'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 台北 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 台北's coordinates.