Summary<\/p>\n
A blue moon will grace the sky this weekend, marking the second full moon in a single month.
\n The celestial event occurs roughly every two to three years.
\n Despite its name, the moon will appear its usual silvery white or golden hue in the night sky.<\/p>\n
\n AI-generated summary was reviewed by a CNN editor.<\/p>\n
\n You\u2019ve probably heard the phrase \u201conce in a blue moon.\u201d Maybe you\u2019ve even used it to describe an occasional occurrence in your life \u2014 the frequency with which you buy a new cellphone, for example.\n <\/p>\n
\n But this weekend will bear witness to a true blue moon: the second full moon to appear in the sky in a single month.\n <\/p>\n
\n The celestial event comes around seven times every 19 years or roughly every two to three years, according to EarthSky<\/a>.\n <\/p>\n \n The moon cycle has eight lunar phases<\/a>, and it lasts 29.5 days \u2014 just shy of a typical month\u2019s length. As a result of this mismatch, the occasional month will host two full moons. The second of these moons is called a blue moon \u2014 a calendrical blue moon, to be precise.\n <\/p>\n \n Sometimes a single year can even feature two blue moons. In 2018, January and March both had two full moons, while February lacked one. The next time this phenomenon will happen is in 2037, according to The Old Farmer\u2019s Almanac<\/a>.\n <\/p>\n \n Another type of blue moon is a seasonal blue moon. This occurs when four full moons, rather than the usual three, appear within a three-month season. Within the lineup, the third one is called the blue moon. The next seasonal blue moon will rise on May 20, 2027.\n <\/p>\n \n Despite its colorful name, Earth\u2019s satellite will appear its typical silvery white or golden hue.\n <\/p>\n \n The phrase \u201cthe moon is blue\u201d dates back to the 1500s and was used to describe something thought to be impossible, which is where the term \u201cblue moon\u201d comes from, according to Brittanica<\/a>.\n <\/p>\n \n However, the 1937 Maine Farmer\u2019s Almanac was where the phrase was first documented, and it stuck, evolving over time to refer to the celestial event as we know it today, noted Dr. Pamela Gay, senior scientist at the Planetary Science Institute.\n <\/p>\n \n It is, however, possible for the moon to appear blue when our planet\u2019s atmosphere contains smoke or dust particles that are a hair wider than 900 nanometers<\/a>, although it\u2019s a rare occurrence. In 1883, people reported observing the moon turning blue after the eruption of Indonesia\u2019s Krakatoa volcano, according to Brittanica<\/a>.\n <\/p>\n \n May\u2019s blue moon will appear fullest, or peak, at 4:45 a.m. ET on Sunday before the sun rises. This event will also feature a micromoon, which means it will be near its farthest point from Earth in its orbit, according to EarthSky<\/a>.\n <\/p>\n \n Because the moon\u2019s orbit around Earth isn\u2019t a perfect circle, its apparent size varies by about 10% at different points in its orbit, Gay said. The nearest point is called the perigee and the farthest the apogee. A full moon around the time of apogee is a micromoon \u2014 and the upcoming event will be this year\u2019s most distant full micromoon.\n <\/p>\n \n Sunday\u2019s moon will be about 252,334 miles (406,093 kilometers) from Earth, compared with its average distance of about 238,855 miles (384,400 kilometers), according to NASA<\/a>. However, the silvery orb won\u2019t look noticeably smaller to the unaided human eye.\n <\/p>\n \n \u201cIf you\u2019re used to comparing the moon to known things in your landscape \u2014 or holding your thumb up at arm\u2019s distance to compare it to your thumb \u2014 you can see that 10% difference. But to the average person you\u2019re not going to notice the difference at all,\u201d Gay said.\n <\/p>\n \n The last calendar blue moon, which took place in 2023, was no micromoon. In fact, it was the opposite: a supermoon, when the full moon coincides with perigee \u2014 its closest approach to Earth. At perigee, the moon is about 226,000 miles (363,300 kilometers) away from Earth, according to NASA<\/a>.\n <\/p>\n \n For the Americas, Africa and Europe, the moon will appear fullest the night of May 30. Australia, New Zealand and Asia will find the brightest full moon on the night of May 31.\n <\/p>\n \n \u201cWhen that moon is rising, sometime between 5:30 and 6:30 in your time zone, and the sky is still this beautiful blue, there\u2019s not a lot of weird settings to fuss with, your cellphone will take care of all the details for you,\u201d Gay said. \u201cThis time of year is really kind of an awesome time to get those photos of the full moon.\u201d\n <\/p>\n