The Moon does not emit its own light, shining instead by reflecting sunlight. Depending on the relative positions of the Earth, Sun and Moon, varying amounts of the lunar surface appear to be illuminated.

When the Moon is between the Earth and the Sun, the bright side of the Moon is facing away from the Earth, and we have a New Moon (position A in the diagram below).

The New Moon rises at sunrise, transits the meridian at noon and sets at sunset. The New Moon phase repeats every 29.531 days – one synodic month.

Solar eclipses can only occur within a few days of the New Moon, but they do not happen at every New Moon. This is due to the 5.1 degree tilt of the Moon’s orbit around the Earth compared to the Earth’s orbit around the Sun. The intersection of these two orbits is the line of nodes, and solar eclipses occur when this line is pointing towards the centre of the Sun.