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--- photo:light_pollution [2026/04/16 23:31] – [light pollution] gary1
+++ photo:light_pollution [2026/04/16 23:43] (current) – [Twilight] gary1
@@ Line 86: / Line 86: @@
   * Where there's no light pollution the limiting magnitude is usually assumed to be 6.5, though some people can see fainter. Under such conditions, the sky is packed with stars, the Milky Way is a mass of swirling, jumbled detail and any clouds appear blacker than the sky itself.
-=====Twilight=====
-  *the sun obviously also causes major effects on sky brightness before sunrise and after sunset
-  *if there is any sun above the horizon, only objects with magnitude brighter than about minus 2 (eg. Venus, Jupiter, moon, occasionally Mars at opposition) can be seen - albeit with difficulty in daylight
-  *remember the sun moves 15deg per hour due to earth's rotation but rate that it disappears depends upon latitude from the equator and season
-  *the sun through the year follows the ecliptic which is tipped 23½° with respect to the celestial equator (the same plane as the equator on Earth).
-  *depending on the season and the observer’s latitude, the Sun may appear to set at a steep or a shallow angle relative to the horizon.
-  *at latitude more than 68° north or south, depending on the season, the Sun may not rise or set at all.
-  ***Twilight Stages: ()**
-    * **Civil Twilight (Sun 0° to 6° down):**
-      * only the brightest stars (magnitude 0 or brighter, like Sirius, Vega, Arcturus) and planets (Venus, Jupiter) are visible.
-    * **Nautical Twilight (Sun 6° to 12° down):**
-      * 1st magnitude stars appear as the sky gets darker.
-    * **Astronomical Twilight (Sun 12° to 18° down):**
-      * by the end of this period, 6th magnitude stars (naked-eye limit) become visible, particularly at the zenith.
 =====astrophotography in areas of light pollution:=====