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© T A Rector/I P Dell'Antonio/NOAO/AURA/NSFThe Moon orbits Earth in an elliptical path that brings it 50,000 km closer to our planet on one side of its orbit than on the other.

The Moon will shine especially bright this weekend, as it will come closer to Earth during its full phase than at any other time in 2009.

The Moon does not orbit Earth in a perfect circle. Instead, it follows an elliptical path that brings it 50,000 kilometres closer to our planet on one side of its orbit (called perigee) than the other (apogee).

On Saturday, 10 January, the Moon will reach perigee, coming within 357,500 kilometres of Earth. The next day, it will enter its full phase, when its disc appears completely illuminated by the Sun.

This will make it about 14% bigger and 30% brighter than typical full Moons (see the difference in the full Moon's size in 2004).

This full Moon will be the biggest of 2009, but it will not loom quite as large as the one last month. On 12 December 2008, perigee occurred about 1000 km closer to Earth than the upcoming event and occurred just four hours before the Moon entered its full phase.

That full Moon holds the title as the biggest during the period from 1993 to 2016, though to observers it will be virtually indistinguishable from this weekend's Moon.