Weather threatens lunar spectacle

South Africa is the perfect place from which to view tonight's full lunar eclipse, but residents of the Western and Northern Cape might not get to see the event.

Overcast conditions in both provinces threaten to bring the curtain down on the show.

Professor Derck Smits from Unisa said the moon would turn dark and red in colour during the eclipse, which would last from 9.22pm until 11.03pm tonight.

Smits said the earth's shadow had two parts - the penumbra (partial shadow) and the umbra (complete shadow).

"The moon passes through the umbra, an umbral eclipse occurs and the moon will turn into a red colour," he said.

"The earth's atmosphere tends to scatter blue light. This then results in only red light passing through, causing the moon to be red in colour."

However, weather expert Mnikeli Ndabambi warned: "A frontal system will be approaching from the south-west of the country, resulting in cloudy to overcast conditions over most areas of the Western Cape as well as the western part of the Northern Cape. This might obscure the lunar eclipse," said Ndabambi.

Smits said the eclipse should be most clearly visible to residents of Gauteng, Limpopo, Mpumalanga, KwaZulu-Natal, eastern parts of North West, the eastern Free Sate, and the eastern part of the Eastern Cape.

Smits said if an astronaut were to stand on the moon during the eclipse, the sun would be completely blocked by the earth and would illuminate the earth's atmosphere from behind.

"The astronaut would see a red ring of sunsets and sunrises surround the earth."