Day and night cycle



The day and night cycle, of the Terraria world, refers to the rising and setting of the Sun and Moon, and the ways this can affect the world.
 * Day begins at 4:30 a.m., while night begins at 7:30 p.m.
 * Day and Night each have their own respective theme music in some surface biomes.
 * Some surface enemies only spawn at night (see Enemies below).
 * Some NPCs sell unique items at night.

Note that the Sun in Terraria rises at the left of the map, even though the left is referred to in-game as "West" (the same for right/East), eg. when a Goblin Army, Frost Legion, or Pirate Invasion begins approaching.

Time

 * All newly-created Worlds begin at 8:15 a.m.
 * In-game time can be displayed by equipping a Watch, GPS, PDA, Cell Phone or can be checked from a Grandfather Clock.
 * One minute of in-game time lasts one second of real-world time, meaning one hour in-game lasts one minute real-world. One Terraria day therefore lasts 15 real-world minutes, and night lasts 9 real-world minutes.
 * As of 1.3.0.1, time can be sped up to the end of the current cycle once every seven days, using the Enchanted Sundial.

Mobile Time
In the, before Hardmode is initiated, the day/night cycle occurs at a dynamic rate. In order to accommodate the shorter play times that mobile game sessions tend to entail, day and night last for shorter overall periods, and boss or event fights can cause the day or night period to extend in order to offer players more time to complete them. Once Hardmode begins, the day and night cycle will progress at the same speed as in other versions.

Enemies
At the surface layer, unique enemies spawn at night. Nocturnal enemies will run or fly away when the day starts.

Additionally, many bosses can only be summoned successfully and fought during the night, including Eye of Cthulhu, Skeletron, The Twins, The Destroyer, Skeletron Prime and Ocram.

In contrast, King Slime can only spawn randomly during the day, though it can be summoned with the Slime Crown at any time.

Night-only enemies

 * Demon Eye
 * Raven (only during Halloween)
 * Zombie
 * Blood Zombie (during a Blood Moon)
 * Drippler (during a Blood Moon)

Night-only Hardmode enemies

 * Clown (during a Blood Moon)
 * Hoppin' Jack (only during Halloween)
 * Possessed Armor
 * Wandering Eye
 * Werewolf (during a Full moon)
 * Wraith

Achievement
You Can Do It! is the achievement you earn for surviving your first full night ( only).

Trivia

 * You can grab the sun or the moon on the title screen and move it around.
 * Before formal server software was released for Terraria, and while it was necessary to open a second window of Terraria to host a server, you could drag the sun or moon around to directly change the time of day within the server.
 * If you are wearing sunglasses, the sun will appear to be wearing them too. Un-equipping the sunglasses will cause it to revert back. This has no functional effect.
 * Internally, the time counter is reset to zero at both dawn and dusk. During daytime, the counter is allowed to go up to 54000, and during nighttime it is only allowed to go up to 32400.