Astronomy is the observation of space and the sky.
The sky is a great expanse of far background visible when no block or back wall acts as a barrier. Objects within it move in circular patterns, although at an equator they may appear to move vertically. It has a cycle characterized by four parts: dawn, day, dusk, and night.
When dawn starts, the sky brightens and then turns pinkish orange as the moon and stars disappear. The light level starts to increase. Solar panels will create some electricity.
During the day, in the Blockhead's world, the sun rises from the east and sets in the west. The light level will usually be at its greatest. Stars disappear and the moon sets. Solar panels will generate the most electricity.
Similarly to dawn, the sky turns pinkish orange but the light level will decrease instead. Stars will slowly appear. Solar panels will create some electricity.
The sun disappears. The moon rises and stars appear. The light level is low. Dropbears will attack blockheads passing by their location and occasionally roam from tree to tree. Scorpions will become more aggressive. Solar panels will generate little to no electricity.
There are three types of objects that can be seen in the sky: the sun, the moon, and stars. Noting their motion may allow a player to identify where a part of a world is in the world. For example, if the sun rises straight ahead of you, you are probably near the east equator.
The sun is a very bright, white object slightly larger than a block in size, directly visible only during dawn or dusk (depending on the viewing location). It's so bright that it lightens the color of the sky near it, the closer the brighter. Overcast conditions will reduce this effect and possibly keep the sun from being visible at all.
The moon is an object of similar size to the sun but not quite as bright. Like the sun, it tends to brighten nearby sky and is directly visible only during dusk or dawn (whenever the sun isn't). It's easily recognized by its mottled pattern.
Stars are very small spots of light visible in the night sky. They appear as if it were the same season, time of day, and latitude, at 0° longitude.