We're all gearing up for tonight's penumbral lunar eclipse. Royal Observatory Astronomer, Colin Stuart, tells us what it is and how to see it.
Sky-watchers across much of the world are gearing up to observe a lunar eclipse. Starting at 10:34pm this evening (GMT) the Earth’s shadow will start to encroach onto the surface of the Moon. Those with clear skies should be able to spot this as a slight dimming in the usual brightness of the Moon. The effect, which peaks at 2:53 am (GMT) on Saturday morning, will be visible from Europe, Africa, a lot of Asia and most of North America.
We only see the Moon because it reflects light towards us from the Sun. Lunar eclipses occur when the Earth either completely, or partially, blocks the path of light from the Sun to the Moon. The event this evening is known as a penumbral lunar eclipse – the Moon will only partially move into the Earth shadow (or umbra). Lunar eclipses of this kind are not as spectacular as a full blown lunar eclipse when the Moon turns blood red as the Earth blocks almost all light from the Sun reaching the lunar surface and only the light filtering through our atmosphere is bounced back to us.
By chance, the eclipse will be accompanied by the return of a comet known as 45P. This ice mountain is set to make its closest approach to the Earth since 2011 on the same night as the eclipse. However, early observations suggest it may not be as bright as astronomers had first hoped, although it may still be worth trying to track down as it won’t be back again until 2022. You need to be looking just under the famous four stars known as “The Keystone” in the constellation of Hercules in the pre-dawn sky.