#Half life the gate driver#

It then receded to a wider orbit because of tidal interaction with the Earth. The most widely accepted origin explanation posits that the Moon formed about 4.51В billion years ago, not long after Earth, out of the debris from a giant impact between the planet and a hypothesized Mars-sized body called Theia. That said, 59% of the total lunar surface can be seen from Earth through shifts in perspective due to libration. The Moon is tidally locked to Earth, which means that the length of a full rotation of the Moon on its own axis causes its same side ( the near side) to always face Earth, and the somewhat longer lunar day is the same as the synodic period. During each synodic period of 29.5 days, the amount of visible surface illuminated by the Sun varies from none up to 100%, resulting in lunar phases that form the basis for the months of a lunar calendar. The Moon's orbit around Earth has a sidereal period of 27.3 days. Its surface gravity is about one-sixth of Earth's ( 0.1654 g) Jupiter's moon Io is the only satellite in the Solar System known to have a higher surface gravity and density.

The Moon is classified as a planetary-mass object and a differentiated rocky body, and lacks any significant atmosphere, hydrosphere, or magnetic field.

#Half life the gate driver#

Orbiting Earth at an average distance of 384,400В km (238,900В mi), or about 30 times Earth's diameter, its gravitational influence slightly lengthens Earth's day and is the main driver of Earth's tides. At about one-quarter the diameter of Earth (comparable to the width of Australia), it is the largest natural satellite in the Solar System relative to the size of its planet, the fifth largest satellite in the Solar System overall, and is larger than any known dwarf planet. The Moon is Earth's only natural satellite.