I'm the moon. I go around the planet you live on about 13 times a year! Yup in a year. I am made outta stone. Where I am there is no gravity. I'm not hollow. I appear to you at night.
As the Sun sets, the Moon rises with the side that faces Earth fully exposed to sunlight The Moon has phases because it orbits Earth, which causes the portion we see illuminated to change. The Moon takes 27.3 days to orbit Earth, but the lunar phase cycle (from new Moon to new Moon) is 29.5 days. The end.
Moon phases go like this; New moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter, Waning Crescent.
Facts about me: The Moon (or Luna) is the Earth's only natural satellite and was formed 4.6 billion years ago around some 30–50 million years after the formation of the solar system. The Moon is in synchronous rotation with Earth meaning the same side is always facing the Earth.