How far from the Earth is the Moon?
The average distance between the Earth and Moon is approximately 384,400 kilometers. This measurement is obtained by calculating the average distance between the two celestial bodies at different points in their orbits. The most accurate method of measurement uses lasers directed at reflectors left on the lunar surface by the Apollo missions, enabling precise estimation of the time taken for signals to return to Earth.
It is interesting to note that, despite this considerable distance, scientists have managed to establish stable communication with the manned and robotic missions sent to the Moon, a remarkable testimony to technological progress.
The Moon orbits the Earth in an elliptical trajectory, i.e. it moves in an oval shape, moving closer to and further away from the Earth with each orbit. This movement is the result of the gravitational influence between the Earth and the Moon.
The Moon’s position in the sky varies, and this change is responsible for the lunar phases observed from Earth. These phases are the result of the amount of sunlight the Moon’s visible surface receives at different times during its orbit.
The distance between the Earth and the Moon is not fixed. It fluctuates due to the Moon’s elliptical orbit and the gravitational forces at play. The main forces responsible for these variations are gravitational tides, which are generated by differences in the force of gravity exerted by the Moon at different locations on Earth, and vice versa.
One notable phenomenon is that the Moon is progressively moving away from the Earth at a rate of around 3.8 centimetres per year, a process precisely measured through analysis of laser signals reflected from the lunar surface.
The duration of the journey from the Earth to the Moon depends on the trajectory and speed of the mission. The Apollo missions, for example, took around three days to reach the Moon. However, this time may vary according to the route taken by the spacecraft and the nature of the mission.
Trips to the Moon have been made using different technologies and for different purposes, influencing the trajectories chosen and, consequently, the duration of the missions. These missions remain milestones in space exploration, testifying to man’s ingenuity and perseverance.