Earthshine tonight: How to see June’s spectacular Moon event

This may be your last chance this year to spot this incredible phenomena.

By Holly Spanner

Published: Thursday, 15 June 2023 at 12:00 am

There is more than just the Moon’s phases and craters to capture our attention. For the last couple of months, a subtle, ethereal glow has been appearing on the Moon, with this month potentially being the last chance to see it. If you’re finding yourself marvelling at how beautiful the Moon is, you’re not alone; this celestial phenomenon that has fascinated observers for centuries.

If you want to learn more about when you can see this ghostly glow, why it happens and what it has to do with Leonardo da Vinci, read on.

Why not escape the sweltering indoor temperatures and make the most of clear nights this year with our full Moon UK calendar and astronomy for beginners guide?

When can I see Earthshine?

If the clouds hold, you can see Earthshine tomorrow morning, 16 June 2023, before sunrise at 4:42am BST (5:24am EDT, New York City).

Earthshine is visible in the early morning a few days before the new Moon, and in the evening a few days after new Moon. So whether you’re a lark or a night owl, you needn’t miss out on seeing the Moon’s ghostly glow.

Here are the next opportunities to see Earthshine on either side of the new Moon on 18 June 2023:

Earthshine is not visible all year round; April and May are the best months. However, we may be treated to an epilogue this month in June, although it may not appear as bright as last month.

What is Earthshine?

Earthshine is the faint illumination on the Moon, from Earth’s reflected sunlight.

Sunlight reflects off the Earth and reaches the Moon’s surface, brightening the otherwise unlit part of the lunar disk (not to be confused with the ‘dark side’ of the Moon, which is tidally locked away from us).

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The thin waning 26-day-old Moon is low in the dawn sky. It’s reddened by the low altitude and twilight colours but still shows some Earthshine on the unlit side of the Moon. Image credit: Getty images

Earthshine is also referred to as the Da Vinci glow, and its intensity can vary based on factors like atmospheric conditions, Earth’s albedo (reflectiveness), and the observer’s location.

It’s a beautiful sight and is certainly worth looking out for in these early Summer months.

Why can you only see Earthshine during a crescent Moon?

The reason Earthshine is so visible during a crescent Moon is simply because the illuminated portion of the Moon is slimmer. This allows for a larger portion of the darkened Moon to be illuminated by Earthshine, and the contrast between the illuminated and dark regions is more apparent.

June is perhaps the last good opportunity to view Earthshine this year, as during the spring, the northern hemisphere is tilted towards the Sun before starting to tilt away after the solstice. It’s aided, too by the higher latitudes, where the last of the lingering winter snow and ice still provide some ground cover, reflecting more light than the darker-coloured vegetation and water, so we get more apparent Earthshine.

While you might expect therefore, that Earthshine would be brighter during the winter months when snow and ice cover is prolific, the amount of light reaching the Arctic is significantly less – the Sun not even rising in the very high latitudes – so Earthshine is not as eventful during the winter.

Why is it called the Da Vinci Glow?

Earthshine has been documented for centuries. Back in Renaissance Italy, when Leonardo da Vinci was observing the night sky in the 16th Century, he made detailed drawings and sketches of celestial bodies, including the Moon.

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A depiction of Earthshine, as drawn by polymath Leonardo da Vinci in the 16th Century. Image by Getty Images

Da Vinci meticulously documented his astronomical observations, noting the positions, phases, and features of these objects, including a sketch of Earthshine in the corner of one of his manuscripts. Through his detailed notes, many have adopted the term ‘Da Vinci Glow’, although he did not coin the term himself.

What affects Earthshine?

There is a combination of different factors that affect the appearance and intensity of Earthshine, including the Earth’s cloud cover, the composition of its atmosphere, and the angle of sunlight reflecting off our planet onto the Moon.

Changes in cloud cover are one of the main factors affecting how bright Earthshine will be; the cloudier the Earth, the brighter Earthshine will appear. Of course, we still need to be able to see the Moon – so it’s all a matter of balance.

Earthshine will therefore vary in brightness and colour, so it can be different from one month to the next.

Earth’s atmosphere also plays a crucial role in how Earthshine appears to us. As light from the Sun passes through our atmosphere, it undergoes scattering and absorption, with different wavelengths being affected differently. The presence of particles or pollutants, for example, can affect the scattering of light and alter its colour.

This atmospheric filtering influences the colour and intensity of the Earthshine, and it’s this light that is ultimately reflected back to the Moon.

Different types of ground cover will reflect different amounts of light. Land, for example, reflects around 10-25 per cent, while clouds reflect the most; around 50 per cent of light.

What equipment do I need to see Earthshine?

Good news – you don’t need any special equipment to see Earthshine; just your eyes. If you want to pick out some of the features you wouldn’t normally see, then a pair of binoculars or a telescope will come in handy, and allow for a closer view of the Moon’s surface. Why not grab a pencil and sketchbook and recreate some of da Vinci’s sketches yourself?

If you’re in a typical, non-air-conditioned British house, then you might like to escape the accumulated heat for a while and make the most of the cooler night air. Set up a recliner, beanbag, or hammock outside and look towards our celestial neighbour. You may even glimpse a sporadic meteor if you’re lucky.

Just remember; if you fall asleep – sunrise is around 4:42am in southern England, so you’ll be woken up early!

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