Lunar eclipse today: How to see the May 2023 penumbral eclipse

Hot on the heels of the hybrid solar eclipse back in April, a lunar eclipse of the full flower Moon is set to occur the night before the Coronation (although it won't be visible in the UK).

While not as dramatic as a total lunar eclipse, it will be the deepest penumbral eclipse until 2042.

But what time does the lunar eclipse take place? Where in the world will it be visible? And, will the Moon turn red during this lunar eclipse? Answers to these questions, and more, are below.

If you’re looking forward to making the most of the warm nights this year, why not plan ahead with our full Moon UK calendar and astronomy for beginners guide?

When will the penumbral lunar eclipse occur?

The penumbral eclipse will occur on 5 May 2023. It will occur at 3:14pm UTC (4:14pm BST), however because the Moon will be below the horizon at this time, we will not be able to see the eclipse from the UK.

The Moon will rise at 8:35pm on 5 May and set at 5:31am the next morning.

The penumbral eclipse will be visible from parts of Europe, Asia, Australia, Africa, the Pacific, the Atlantic, the Indian Ocean and Antarctica (times vary with location). According to Time and Date, this will be the deepest penumbral eclipse until September 2042.

• Penumbral eclipse begins: 5 May, 3:14pm UTC*
• Maximum: 5 May, 5:22pm UTC
• Penumbral eclipse ends: 5 May, 7:31pm UTC
• Coverage: 98.7 per cent of the Moon

*UTC is one hour behind BST

The penumbral eclipse will occur when the Moon is in the constellation Libra.

What is a penumbral lunar eclipse?

The eclipse on 5 May is not a full lunar eclipse, nor a partial lunar eclipse - it's a penumbral lunar eclipse.

A penumbral lunar eclipse occurs when the Moon passes through the Earth's penumbral shadow, which is the lighter, outer part of the Earth's shadow. The Moon will not pass through the darker central part of the Earth's shadow (the umbra). The resulting effect is subtle, and viewers may see the Moon darken, but not disappear.

In contrast, during a partial lunar eclipse, the Moon passes through the Earth's umbra, the inner, darker part of the Earth's shadow. During a total lunar eclipse, the Moon passes completely into the shadow cast by the Earth. This causes the Moon to appear partially or completely reddish-brown, giving it the nickname 'Blood moon'.

What causes a lunar eclipse?

During a lunar eclipse, the Sun, Earth, and Moon align perfectly, causing the Earth's shadow to block sunlight from reflecting off the Moon's surface. While the Moon does not disappear entirely, during a full lunar eclipse it will turn a bright, copper-red colour.

The Moon goes through different stages during a lunar eclipse, first passing into the penumbra (the outer part of the Earth's shadow), then into the umbra at totality, before returning to the penumbra on the other side, and finally leaving the shadow altogether.

During the penumbral eclipse on 5 May, the Moon will not pass into the umbra (it just misses it), remaining only in the penumbra.

Will the Moon turn red?

Sadly, no. The Moon will not turn red during the eclipse on 5 May 2023, as it does during a total lunar eclipse. The Moon may appear slightly darker or perhaps even reddish, but the effect is much more subtle than during a total lunar eclipse.

So, what will we be able to see?

"Unfortunately, this will be a disappointing lunar eclipse for two reasons," says Dr Darren Baskill, astronomy lecturer at the University of Sussex.

"Firstly, for us in the UK, the eclipse ends just before the Moon rises. While the very south-eastern tip of England is a theoretical exception, as the Moon rises there 45 minutes earlier than it does over Scotland, it will still be daylight as the Moon rises over Kent, and so impossible to notice the eclipse by eye!"

"Secondly, even if you are in a favourable location on Earth – such as in Asia – it will be difficult to notice any changes, as on this occasion, the Moon is travelling through the Earth’s outer, lighter, 'penumbral' shadow, and not the darker, central, “umbral” shadow."

"So no matter where you are on Earth, the Moon will not go dark red like it does when it passes through the heart of the Earth’s shadow. Instead, it will just dim slightly as it passes through the Earth’s lighter outer shadow," explains Baskill.

What’s the difference between the Earth’s umbra and penumbra?

During a lunar eclipse, two shadows are cast on the Moon: a lighter, outer shadow called the penumbra, and a darker, inner shadow called the umbra.

"Everything – including the Earth and yourself! - has two types of shadow: the dark heart of the shadow called the umbra, and then a lighter outer shadow around it, called the penumbra," says Baskill.

And our expert has a nifty experiment that you can try yourself:

"At night, hold your hand roughly 60cm (or two feet) over white paper and beneath your ceiling lights, and you will see that your hand has both a deep shadow in the middle, and a lighter outer shadow around the edge," Baskill explains.

The degree of immersion of the Moon in the umbra defines the type of eclipse observed.

When the Moon partially passes through the umbra, it results in a partial lunar eclipse, while a total lunar eclipse occurs when the Moon enters, and is fully shrouded by, the umbra.

When is the next lunar eclipse?

The next partial lunar eclipse will occur on 28 October 2023, while the next penumbral lunar eclipse will occur on 25 March 2024. But we’ll have to wait until 14 March 2025 for the next total lunar eclipse, when we'll also be treated to another two total lunar eclipses in (relatively) quick succession: 7 September 2026 and 3 March 2026.

Here is a list of the upcoming lunar eclipses:

• 5 May 2023: Penumbral
• 28 October 2023: Partial
• 25 March 2024: Penumbral
• 18 September 2024: Partial
• 14 March 2025: Total
• 7 September 2025: Total
• 3 March 2026: Total
• 28 August 2026: Partial
• 20 February 2027: Penumbral

Why does a lunar eclipse only happen during a full Moon?

Similar to a solar eclipse, which can only occur during a new Moon, a lunar eclipse can only happen when the Moon is full. It occurs when the Sun, Earth, and Moon are in perfect alignment, and this alignment only takes place during the full Moon phase of the lunar cycle.

"A lunar eclipse always occurs either two weeks before or after a solar eclipse, and since there was a solar eclipse on 20 April 2023, the accompanying lunar eclipse occurs on 5 May," Baskill says.

Viewing tips

Unlike solar eclipses that require special equipment to observe safely, lunar eclipses can be viewed with the naked eye. This is because the Moon only reflects sunlight and doesn't emit any dangerous radiation. During a lunar eclipse, the Moon doesn't get any brighter than a full Moon, so it is safe to watch without protective gear.

To observe a lunar eclipse, all you need is clear skies and a good view of the Moon. It's recommended to avoid areas with high light pollution to enhance visibility.