Exploring the myth<\/strong><\/h2>According to myth-busting website Snopes.com, the idea can be traced back to a meme that first appeared in 2016<\/a>.<\/p>That meme said simply:<\/p>
“Save the date: May 29th<\/sup>, 2016. Green moon visible for first time since 1847.”<\/p>While that original post got some traction, the rumour of the green Moon really took off when someone reposted a version of it in 2018 \u2013 now with an added pseudoscientific explanation involving the full Moon\u2019s proximity to blue-hued Uranus in the night sky, and with the date of this supposed upcoming celestial wonder changed to 20 April.<\/p>
That date should have been a clue \u2013 but more on that in a moment.<\/p>
Can the Moon ever appear green?<\/strong><\/h2>![\"The](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/48\/2022\/12\/07.LunarEclipseMaximumTotalityMichaelShapiro-f3d1962-e1676626673547.jpg\")
The rusty red hue of a lunar eclipse. Credit: Michael Shapiro, Farmington Hills, Michigan, USA, 8 August 2022<\/figcaption><\/figure>There are only two reasons the Moon might appear green: either it actually is<\/em> green, or something is happening to the light that reflects off its surface, before it reaches our eyes, that makes it appear<\/em> green.<\/p>We\u2019ll assume you know the Moon isn\u2019t actually green. If it was, it would look green every night, not once every 420 years, as that April 2018 post claimed!<\/p>
But could something make it appear green? That\u2019s a much more sensible question.<\/p>
After all, we sometimes see a \u2018Blood Moon\u2019 that appears orange or red in hue.<\/p>
You\u2019ll see these when there\u2019s a lunar eclipse<\/a>, because the only light reaching the Moon from the Sun, during such an event, is red light that has been refracted towards the Moon by Earth\u2019s atmosphere (with blue wavelengths, conversely, refracted outwards into space).<\/p>![\"The](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/48\/2023\/05\/orange-moon-09a1b76.jpg\")
The Moon appears orange when close to the horizon. Credit: Ambre Haller \/ Getty Images<\/figcaption><\/figure>For similar reasons, you’ll often see a Moon close to the horizon appear orange<\/a>, because sunlight reflected from its surface towards the observer has had to pass through a thicker part of Earth’s atmosphere.<\/p>The Moon can also sometimes appear red or orange if seen through skies that are dense with pollutants such as ash from volcanos or smoke from forest fires.<\/p>
In rare, extreme cases, such particles can also have the reverse effect, scattering red light and making the moon appear blue.<\/p>
Though the phrase \u2018blue moon<\/a>\u2019 usually refers to either the second full Moon in a month, or the third full Moon in a season of four, and has nothing to do with colour at all.<\/p>How to make the Moon green<\/strong><\/h2>![\"You](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/48\/2024\/10\/GettyImages-517153770-scaled.jpg\")
You could use a green camera filter to photograph a ‘green’ Moon. Credit: iStock \/ Getty Images Plus<\/figcaption><\/figure>There are no known natural or atmospheric phenomena that would make light appear greener than it is.<\/p>
If you wanted to make the Moon appear green you could:<\/p>
- Observe or photograph the Moon through a filter (or the bottom of a beer bottle!)<\/li>
- Photograph the Moon then edit it to produce a verdant hue<\/li><\/ul>
Those things can make the Moon appear green, but no known natural phenomenon will.<\/p>
And if the Moon isn\u2019t green, and if nothing is happening to its light to make it appear so\u2026 then you\u2019re not going to see a green Moon, are you?<\/p>
So why do people think you might?<\/p>![\"Astronomers](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/48\/2024\/05\/telescope-filters-planets-guide.jpg\")
Astronomers attach coloured filters to their telescopes to bring out specific features in planets and other targets.<\/figcaption><\/figure>Green Moon and 420<\/strong><\/h2>It helps if you understand that \u2018420\u2019 has long been a US slang term for marijuana\/cannabis, and that \u20184\/20\u2019 (April 20) is now celebrated by some as so-called ‘International Weed Day’.<\/p>
Once you\u2019re equipped with that information, claims that \u201cthe Moon is going to turn the colour of marijuana for the first time in 420 years on 20 April\u201d don\u2019t sound quite so credible!<\/p>
Basically, the whole idea is a joke and nothing more.<\/p>
Except, there\u2019s a kicker here\u2026 because in the course of researching this article, we found a letter published in scientific journal The Observatory\u00a0way back in 1884, which mentions “the most interesting phenomenon” of a green-hued Moon having been observed during “the recent remarkable sunsets as seen in this climate.”<\/a><\/p>That raises the intriguing possibility that someone, somewhere actually HAS seen a green Moon at some point \u2013 but if they did, then the explanation is beyond us (and apparently beyond NASA, too).<\/p>
Someone who posted the 1884 letter on Quora suggested it may be “an optical illusion due to how the visual processes in your brain produce the experience of colour.”<\/p>
Green flash of the Moon<\/strong><\/h2>![\"Green](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/48\/2024\/10\/green-lunar-flash.jpg\")
Green flash of the Moon captured by ESO Photo Ambassador Gerhard H\u00fcdepohl. Credit: G.H\u00fcdepohl (atacamaphoto.com)\/ESO<\/figcaption><\/figure>There is a phenomenon known as a ‘green lunar flash’, where a small part of the Moon may appear green very briefly when it’s low on the horizon.<\/p>
This, again, is to do with how light from the Moon is reflected and scattered through Earth’s atmosphere before it reaches our retinas and camera sensors.<\/p>
The image above was captured by Gerhard H\u00fcdepohl and you can read about the image and what causes the greenn flash via the ESO website<\/a>.<\/p>There’s a similar effect that occurs with the Sun and also with the planet Venus, the latter known as the green flash of Venus<\/a>.<\/p>Are there any green moons?<\/strong><\/h2>![\"Saturn's](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/48\/2024\/10\/titan-moon-infrared-green.jpg\")
Saturn’s moon Titan isn’t actually green. These are just false-colour images captured in infrared by the Cassini spacecraft. Credit: NASA\/JPL\/University of Arizona<\/figcaption><\/figure>Ok, so our Moon never appears green, except through some sort of optical manipulation, but what about other moons in the Solar System?<\/p>
You may have seen images of green moons around other planets in our Solar System, but these are likely ‘false-colour’ images.<\/p>
That meme said simply:<\/p>
“Save the date: May 29th<\/sup>, 2016. Green moon visible for first time since 1847.”<\/p> While that original post got some traction, the rumour of the green Moon really took off when someone reposted a version of it in 2018 \u2013 now with an added pseudoscientific explanation involving the full Moon\u2019s proximity to blue-hued Uranus in the night sky, and with the date of this supposed upcoming celestial wonder changed to 20 April.<\/p> That date should have been a clue \u2013 but more on that in a moment.<\/p> There are only two reasons the Moon might appear green: either it actually is<\/em> green, or something is happening to the light that reflects off its surface, before it reaches our eyes, that makes it appear<\/em> green.<\/p> We\u2019ll assume you know the Moon isn\u2019t actually green. If it was, it would look green every night, not once every 420 years, as that April 2018 post claimed!<\/p> But could something make it appear green? That\u2019s a much more sensible question.<\/p> After all, we sometimes see a \u2018Blood Moon\u2019 that appears orange or red in hue.<\/p> You\u2019ll see these when there\u2019s a lunar eclipse<\/a>, because the only light reaching the Moon from the Sun, during such an event, is red light that has been refracted towards the Moon by Earth\u2019s atmosphere (with blue wavelengths, conversely, refracted outwards into space).<\/p> For similar reasons, you’ll often see a Moon close to the horizon appear orange<\/a>, because sunlight reflected from its surface towards the observer has had to pass through a thicker part of Earth’s atmosphere.<\/p> The Moon can also sometimes appear red or orange if seen through skies that are dense with pollutants such as ash from volcanos or smoke from forest fires.<\/p> In rare, extreme cases, such particles can also have the reverse effect, scattering red light and making the moon appear blue.<\/p> Though the phrase \u2018blue moon<\/a>\u2019 usually refers to either the second full Moon in a month, or the third full Moon in a season of four, and has nothing to do with colour at all.<\/p> There are no known natural or atmospheric phenomena that would make light appear greener than it is.<\/p> If you wanted to make the Moon appear green you could:<\/p> Those things can make the Moon appear green, but no known natural phenomenon will.<\/p> And if the Moon isn\u2019t green, and if nothing is happening to its light to make it appear so\u2026 then you\u2019re not going to see a green Moon, are you?<\/p> So why do people think you might?<\/p> It helps if you understand that \u2018420\u2019 has long been a US slang term for marijuana\/cannabis, and that \u20184\/20\u2019 (April 20) is now celebrated by some as so-called ‘International Weed Day’.<\/p> Once you\u2019re equipped with that information, claims that \u201cthe Moon is going to turn the colour of marijuana for the first time in 420 years on 20 April\u201d don\u2019t sound quite so credible!<\/p> Basically, the whole idea is a joke and nothing more.<\/p> Except, there\u2019s a kicker here\u2026 because in the course of researching this article, we found a letter published in scientific journal The Observatory\u00a0way back in 1884, which mentions “the most interesting phenomenon” of a green-hued Moon having been observed during “the recent remarkable sunsets as seen in this climate.”<\/a><\/p> That raises the intriguing possibility that someone, somewhere actually HAS seen a green Moon at some point \u2013 but if they did, then the explanation is beyond us (and apparently beyond NASA, too).<\/p> Someone who posted the 1884 letter on Quora suggested it may be “an optical illusion due to how the visual processes in your brain produce the experience of colour.”<\/p> There is a phenomenon known as a ‘green lunar flash’, where a small part of the Moon may appear green very briefly when it’s low on the horizon.<\/p> This, again, is to do with how light from the Moon is reflected and scattered through Earth’s atmosphere before it reaches our retinas and camera sensors.<\/p> The image above was captured by Gerhard H\u00fcdepohl and you can read about the image and what causes the greenn flash via the ESO website<\/a>.<\/p> There’s a similar effect that occurs with the Sun and also with the planet Venus, the latter known as the green flash of Venus<\/a>.<\/p> Ok, so our Moon never appears green, except through some sort of optical manipulation, but what about other moons in the Solar System?<\/p> You may have seen images of green moons around other planets in our Solar System, but these are likely ‘false-colour’ images.<\/p>Can the Moon ever appear green?<\/strong><\/h2>
How to make the Moon green<\/strong><\/h2>
Green Moon and 420<\/strong><\/h2>
Green flash of the Moon<\/strong><\/h2>
Are there any green moons?<\/strong><\/h2>