Earthshine: Rare lunar event to look out for from France this evening
Light reflected off the Earth’s surface will cast onto the dark side of the moon, briefly illuminating the rarely observed side of its surface - but clear skies are needed to see it
Earthshine gives the Moon a faint, blue tinge, and lights up its rarely seen dark side
Thomas Dutour / Shutterstock
It may be possible for stargazers in France to witness a rare lunar phenomenon called Earthshine this evening (February 4).
This is where the glow caused by sunlight reflects off the Earth and shines onto the dark side of the moon, illuminating areas that are rarely seen.
This phenomenon occurs only a few times per year. It happens when “all of the Sun’s light is reflected away from Earth, and the side of the Moon facing Earth is barely visible,” NASA’s Earth Observatory website states.
“Sometimes the dark face of the Moon catches the Earth’s reflected glow and returns that light. The dark face of the Moon has a faint shine, a ghostly version of a full Moon.”
The colour of Earthshine is usually pale blue or turquoise, due to a combination of a blueish colour coming from the Earth and because the Moon’s surface reflects yellow light.
This event may be observable around dusk this evening in France – which is around 18:00 to 18:30.
However, cloudy skies or bad weather will obscure it, so it will only be possible to witness in the right conditions.
It is easier to see in midsummer in the northern hemisphere when the earth reflects more sunlight back to the moon.
But if the skies are clear in your area this evening, it might be worth having a glance towards the Moon.
Earthshine is sometimes known as ashen Moon in English. In French, it is referred to as lumière cendrée, or sometimes Clair de Terre.
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