Full moon (this usage has been noted as "erroneous" by "Sky & Telescope" in 1999). According to either definition, "blue moons" occur with the average frequency of intercalary months, seven times in 19 years, the "Farmers' Almanac" system of "full moon names" effectively defining a lunisolar calendar. Full moon The full moon is the lunar phase when the Moon appears fully illuminated from Earth's perspective. This occurs when Earth is located between the Sun and the Moon (more exactly, when the ecliptic longitudes of the Sun and Moon differ by 180°). This means that the lunar hemisphere facing Earth – the near
Colonization of the Moon serve as a source of construction materials within cis-lunar space. Rockets launched from the Moon would require less locally produced propellant than rockets launched from Earth. Some proposals include using electric acceleration devices (mass drivers) to propel objects off the Moon without building rockets. Others have proposed momentum exchange tethers (see below). Furthermore, the Moon does have some gravity, which experience to date indicates may be vital for fetal development and long-term human health. Whether the Moon's gravity (roughly one sixth of Earth's) is adequate for this purpose, however, is uncertain. In addition, the Moon is the closest large body