Mjeseca

Mjeseca is the genitive singular form of the Croatian, Bosnian, and Serbian noun mjesec, which generally means the Moon or a month. In everyday use, mjesec can refer to the Moon, and mjeseca appears in phrases such as faza Mjeseca (Moon phase) or duljina mjeseca (length of the month). The distinction between Moon and month is typically resolved by context.

The Moon is Earth's natural satellite. It has a mean diameter of about 3,474 km and a mass of roughly 7.35×10^22 kg. It orbits Earth at an average distance of about 384,400 km. A sidereal orbital period is about 27.3 days, while the synodic cycle from one new Moon to the next lasts about 29.53 days. The Moon is tidally locked to Earth, presenting the same hemisphere to the planet. Its surface features include maria (dark basaltic plains), highlands, and numerous impact craters. The Moon lacks a substantial atmosphere and has only a weak, localized magnetic field.

Phases of the Moon arise from the changing relative positions of the Sun, Moon, and Earth, producing the sequence from new Moon to crescent, first quarter, gibbous, and full Moon. The Moon has been central to human timekeeping, navigation, and culture, and it has been the focus of extensive scientific study and exploration, including crewed and robotic missions. In contemporary space programs, interest continues in future research and potential and/or sustained activity on or around the Moon.

The name and concept of the Moon are tied to the broader Indo-European roots for 'month' and 'moon,' reflecting the historical link between lunar cycles and the measurement of time.