On Thursday evening there will be a
penumbral and also partial lunar eclipse visible from the UK.
A penumbral lunar eclipse occurs when the Moon travels only through the outer, fainter part of the Earth's shadow, or 'penumbra'. This happens when the Earth moves between the Sun and Moon but the three do not form a perfectly straight line. The penumbra causes only a slight darkening of the Moon's surface, with the Moon still exposed to some direct sunlight, so this type of eclipse is easy to miss.
During the partial phase of the eclipse, part of the Moon travels through the Earth's full 'umbral' shadow. However, on this occasion only a very small section of the Moon will be covered by the umbra at maximum eclipse, though the whole northern half of the Moon will be darkened by the penumbral shadow.
The penumbral phase of the eclipse should start at about 19.03 BST, though it will only be visible after about 20.00 in the UK as before that the Moon will be below the horizon. Roughly speaking, moonrise is earliest toward the east of the UK, latest toward the West (about 20.11 in London and 20.44 in Glasgow on 25 April).
The partial phase of the eclipse begins at 20.54 BST, with greatest eclipse at about 21.07 when the Moon is closest to the centre of the Earth's full shadow. The Moon will still be near to the horizon, so you'll need a clear view to the East to see it. The partial eclipse ends at 21.21 after only 27 minutes, making it the second shortest partial lunar eclipse of the century. The penumbral phase ends at 23.11, bringing the whole event to a close.
There will be three lunar eclipses in 2013. However, only two are visible from the UK, the other taking place on 18-19 Oct 2013. Sadly we’ll have to wait till March 2015 for the next Solar eclipse that can be seen from these shores.