Red sky at night - stargazers delight

Friday 27 July 2018

A blood moon will greet stargazers tonight as the longest lunar eclipse of the century so far takes place.

The moon will be eclipsed by the Earth for one hour and 43 minutes. The maximum eclipse takes place at 21:00, but the blood moon will have been visible since it rises at 20:52.

It will appear red because when the Earth passes between the sun and the moon – blocking the suns light – the moon appears red, because some of the sun’s light gets bounced around the edge of the Earth to hit the moon. Because blue and violet wavelengths are scattered more than red and orange ones, more of the red wavelengths reach the moon. 

La Societe Guernesiaise Astronomy Section said it should be quite the spectacle. 

“The total eclipse phase will end at 22:13, and the Moon will then gradually re-emerge from the Earth’s umbral shadow (the dark part of the shadow) until 23:19. It will finally leave the less-evident penumbra part of the shadow and regain all its former glory at 00:30.

“At the distance of the Moon (a quarter of a million miles) the Earth’s shadow is about 2½ times the diameter of the Moon. The Moon will pass close to the centre of the Earth’s shadow, so we can expect it to be quite a dark one. It takes place in the constellation Capricorn – not a very rich star field. Nonetheless, being low in the south-eastern sky it should be a lovely sight, and could create some good photographic possibilities, with foreground objects to give added interest as it rises.

“For a good observation it will be best to have an unrestricted view of the south-east part of the sky, such as anywhere on the east and south coasts. No special equipment is needed; it is easily visible with the naked eye, although it may be difficult to see in the early stages because the sky will still be bright.”

And at around 22:00, Mars will become visible just below the Moon, with the planet at its closest point since 2003.