"The Universe is commonly defined as the totality of existence" but that is more of a philosophical position. Empirically we know (or believe) that it is of finite size some believe it is expanding ...
The astronomical zodiac contains a bunch of constellations along the ecliptic. Some sources say there are 13 constellations in the astronomical zodiac. Other sources claim there are 12. According ...
This XKCD what-if talks about rainbows on planets in a binary star system. It points out that there are two types: circumbinary planets, where the planet orbits far from and around both stars ...