Sunrise and sunset in San Nicolás de los Arroyos, Argentina

Each twilight begins at the morning time and ends at the evening one.

• Longest day: December 21, 14 h 22 min, from sunrise at 05:48 to sunset at 20:09.
• Shortest day: June 21, 9 h 57 min, from sunrise at 08:04 to sunset at 18:01.

• Sunrise and sunset mark the moment the Sun’s upper edge touches a level horizon, with the air’s usual bending of light allowed for. Hills, buildings and altitude move what you see by a few minutes.
• Civil, nautical and astronomical twilight end when the Sun is 6°, 12° and 18° below the horizon. Golden hour here is the photographers’ usual definition: the Sun less than 6° above it.
• Worked out when the page loads from NOAA’s solar equations, for 33.3° S, 60.2° W, and accurate to about a minute.

How the layers work, where their data comes from and what they can’t tell you: Day and night, live, The Sun, Moon and planets