Earth
Earth is the home planet of humans. Earth exists approximately 40 light years from the planet of Saylua, in a separate star system in the Milky Way. Earth's radius is about 30% larger than Saylua's radius. Compared to Saylua, however, Earth has a very long orbit of 365 days. Earth's star, the sun, is a yellow dwarf while Saylua's Sayaris is an ultra cool dwarf star. The bright sun of Earth's star system causes Earth's surface to receive almost as much sunlight as Saylua's Saydia, despite Earth being almost 50 times further from its sun than Saylua is from Sayaris. However, unlike Saylua, Earth has a Day/Night Cycle.
Day/Night Cycle
Earth is not tidally locked, which means that it rotates on its axis. This spinning allows different regions of its surface to receive sunlight during different times of day in a rhythm known as the Day/Night cycle. On Earth, the concepts of day and night are both heavily linked to the idea of time with day being generally seen as the time when sun hits the surface of a given region and night being seen as the time when a region is dark. Humans on Earth tend to sleep during the night and do most of their activities during the day, in contrast to the humans on Saylua who choose to sleep at arbitrary times. The 24-hour day originated from Earth as a system to align time against the rotation of Earth's axis. Although Saylua does not have a planetary rotation keep time by, humans on Saylua divide their time into 24-hour days to stay consistent with the time system of Earth.
Moon
Earth has a moon orbiting the planet, which is not to be confused with Saylua's moon, Luaris. Unlike Luaris, Earth's moon is a satellite of the planet, orbiting its host planet about once every 27 days. On Earth, humans frequently referred to their moon simply as "the moon", a practice which is also used in Saylua to describe Luaris. For humans on Saylua, the term "moon" has come to colloquially refer to a bright, highly noticeable celestial body in the night sky rather than a satellite which orbits a planet.
