Find out what a lunar eclipse is and when you can catch the next lunar eclipse in the UK
An eclipse of the Moon occurs when the Earth lies directly between the Sun and the Moon, and the Moon lies in the shadow of the Earth.
For a total lunar eclipse to happen, all three bodies – the Sun, the Earth and the Moon – lie in a straight line. This means that the Moon passes through the darkest part of the Earth’s shadow - the umbra.
But a lunar eclipse isn't always 'total'. There are actually three different types of lunar eclipse.
During a total lunar eclipse, the Moon usually turns a deep, dark red because it is illuminated by light that has passed through the Earth's atmosphere and has been bent back towards the Moon by refraction.
A partial lunar eclipse happens when the Moon passes through the Earth's penumbra (the outer region of the Earth’s shadow), and only a section of it passes through the umbra (the darkest part of the Earth’s shadow).
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.
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.
The table below shows upcoming UK lunar eclipse dates.
When is the next full Moon?
See astronomer Tom Kerss's top tips for observing and photographing a lunar eclipse in the video below.
28 October 2023 partial lunar eclipse - A partial lunar eclipse was visible throughout all of Europe, Asia, Africa, and western Australia. From the UK we only saw a small fraction of the full Moon pass into the umbra. At its maximum, which occured at 21:15, just 12% was in Earth's shadow, with 6% in the umbra.
16 May 2022 total lunar eclipse - This total lunar eclipse was visible over South America, most of North America and parts of Europe and Africa. People in the UK were able to see the lunar eclipse at totality when the entire Moon turned red. The entire eclipse lasted for more than five hours, however, observers in the UK could only see the eclipse from 2.32am – 5.10am as the Moon had set below the horizon by the end of this period.
19 November 2021 - partial lunar eclipse - This eclipse was unusually long, lasting over six hours in total from the moment the Moon entered the Earth's shadow or 'penumbra'. The very early part of the eclipse was visible in the UK, but because of the timings the Moon had set before the eclipse reached its maximum.
Image: An eclipse from a thousand sunsets © Noah Kujawski | shortlisted in Astronomy Photographer of the Year 2022
A lunar eclipse happens between two to five times a year, with a total lunar eclipse occurring at least two every three years.
A lunar eclipse occurs during the full moon phase but an eclipse does not happen every month, even though the lunar cycle is 29.5 days. This is because the moon’s orbit is inclined by 5˚ relative to the Earth’s orbit. This means that as it travels around the Earth it also moves up and down in its orbit.
Since the Earth is around four times wider than the Moon, its shadow can darken the moon for up to five hours depending on conditions. Lunar eclipses can be seen between two and five times every year – from somewhere on the Earth’s surface. Total lunar eclipses are much rarer from one particular location.
When the moon is close to perigee, the closest point to Earth in its orbit, it makes the moon appear slightly larger than usual. This phenomenon has been dubbed a “supermoon”. Much like “blood moon” it is not an official astronomical term. A “supermoon” will appear up to 7% larger than a regular full moon.
Find out more about supermoons
People sometimes refer to a lunar eclipse as a ‘blood moon’ because of the way the Moon can turn a deep coppery red colour during its eclipse.
However, the colour of the Moon during totality will depend on the global state of dust in the Earth’s atmosphere. Dust in the atmosphere blocks out the higher frequency blue light waves, but the longer wavelength of red light is able to still come through.
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Header image: Passage of a Lunar Eclipse © Mike White - Astronomy Photographer of the Year 2023 shortlisted in the Skyscapes category