This Friday (the 27th of July) the Moon will rise into view in the south east around 9.30pm with an unusual red colour. This is due to a rare phenomena known as total lunar eclipse – when the Earth sits directly between the Moon and the Sun.
But why doesn’t the Moon darken if its light supply is cut off by the Earth, and why will it turn a red colour?
The best way to think about this is to imagine yourself standing on the surface of the Moon as the Earth slowly passes in front of the Sun.
As the disc of the Earth begins to occult the Sun it will start to darken until finally the whole of the Earth sits in front of the Sun. But as this takes place something amazing happens. The Earth’s atmosphere refracts the sunlight into an intense circle of vibrant sunset. It’s this ring of fire around the Earth that illuminates the Moon during totality, giving it an eerie red colour.
This far north between 9.30pm and 10.30pm it’ll still be pretty bright outside but the colour change should still be obvious to see. As the evening progresses the eclipse will become partial and will be almost over by midnight.
Totality for this lunar eclipse will be 103 minutes making it the longest in this century. As my animation below shows we won’t be able to witness the start of this eclipse, only its middle and end.
Peak Eclipse 9.21pm
Moonrise (at 57 deg north) 9.35pm
Total eclipse ends 10.13pm
Partial eclipse ends 11.19pm
Eclipse ends 12.28am
Clear skies and happy Moon watching!