Sunrise and sunset in Santa Teresa, Rio de Janeiro, Brazil

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

• Longest day: December 21, 13 h 33 min, from sunrise at 05:04 to sunset at 18:37.
• Shortest day: June 21, 10 h 44 min, from sunrise at 06:32 to sunset at 17:16.

• Sunrise and sunset are when the top of the Sun meets a level horizon, allowing for the usual bending of light by the air. Hills, buildings and height shift 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 22.9° S, 43.2° 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