Sun



The Sun is a sprite appearing in every version of Minecraft (except Classic) that lights up all top-most blocks while it is in the sky. When the player creates a new world the sun starts on the eastern horizon at dawn. As time passes, it will slowly move westward across the sky and over the western horizon while the moon rises on the eastern horizon. Daytime lasts 10 minutes (in real time). Grass blocks will spread most quickly when exposed to sunlight, which is at the high-point of the day, at about time 4300. The deeper underground the player is, the less sunlight will illuminate the ground, and ultimately there will be no sunlight at all. A gap or a vertical shaft in the ceiling of a cavern will allow sunlight to filter in.

Sunlight
Sunlight, in game, is the name given to the light which illuminates all blocks which do not have a shadow cast over them by a non-transparent block positioned vertically above them in the sky, or if it's raining. Clouds do not cast shadows, and shadows are not affected by the position of the sun in the sky. As of Beta 1.5, however, clouds in weather like rain or snow have been darker, and the light coming from the sunlight is not as bright. During these storms the ambient light value during the day will be reduced to 12 from the usual 15, and in thunderstorms the light level will be reduced to 7, allowing hostile mobs to spawn.

Sunlight (or torchlight) can be used to turn dirt blocks into grass blocks, as long as there is an illuminated grass block adjacent to the dirt.

Hostile Mobs
Hostile mobs will not spawn in sunlight, although existing mobs are affected in different ways by the light. Skeletons and Zombies will be set on fire upon entering an area illuminated by sunlight; however, the mobs will try to avoid contact, and will not burn if the mob is in water or in rain. These mobs will also be safe from the sun if they are under shade. Spiders turn neutral while in direct sunlight, until attacked by the player. Endermen will teleport away from players in sunlight. All other hostile mobs, such as Creepers, Slimes, and Silverfish are completely unaffected by sunlight.

Certain Nether mobs will burn, but otherwise all are also unaffected due to their immunity to fire. Some Nether mobs such as zombie pigmen and magma cubes can spawn in all light conditions. In addition, boss mobs do not take damage from sunlight.

History
According to Notch, the Minecraft sun actually used to rise in the north, not in the east. This was a bug, but was left in the game. This was changed in Minecraft Beta 1.9 prerelease 4, so the sun and moon now both rise in the east.

In the 1.9 pre-release 4, both the sun and the moon were changed from being square to having a more rounded look to them. However, since 1.9 pre-release 6 they are square-shaped again, although it is unknown whether they will be back to being exactly like they were or will somehow be modified. Notch said in a Twitter post that it was for 'consistency' purposes.

The Sun and Moon graphics used to be in /terrain in the minecraft.jar. Since the 1.9 pre-release, /terrain isn't used anymore and now the Sun and Moon graphics are in /environment.

Trivia

 * When the sun rises and sets, the blocks change their light level depending on what angle the sun is at (giving the effect of gradually getting lighter at dawn and gradually getting darker at dusk).
 * You can't see the Sun or Moon with Render Distance set to Short or Tiny.
 * The sun is larger during sunrise and sunset.
 * The position of the sun in the sky does not affect lighting and shadows, so a device such as a sundial would be impossible. However, sun-induced shadows will be added to Pocket Edition, making this sort of thing possible.
 * In Creative Mode, it is possible to reach very high y-values using the flying feature. At a y-value of about 576.620, the moon will appear opposite the sun, or, at night, the sun becomes visible opposite the moon, making it seem almost as if the player is in space.
 * If the player is underwater and looks at the sun, it looks the same as the sun at sunset.