Starwatch: an ‘almost total’ eclipse of the moon

People in the Americas and Pacific best placed to view lunar event from start to finish

This week, a full moon occurs on 18-19 November, and for some around the world it will be an almost total" lunar eclipse. A lunar eclipse occurs at full moon, when the moon travels directly behind the Earth and so crosses through our planet's shadow. More than 97% of the moon's disc will be in the darkest part of Earth's shadow, known as the umbra.

The eclipse begins at 6.02 GMT, when the moon's western limb touches the outer edge of the Earth's shadow. This edge does not block out all the sunlight, and is known as the penumbra. It produces a subtle dimming effect that is easily overlooked. Contact with the umbra takes place just before 7.19 GMT, and will cause a distinct shadow to begin crossing the lunar disc. The midpoint of the eclipse, the almost total phase, occurs at 9.03 GMT. The moon then leaves the umbra at 10.47 GMT, and the penumbra just before 12.04 GMT.