The full moon of April, called the Pink Moon, will occur in the eastern U.S. Monday night (April 26), a day before it reaches perigee, the closest point in its orbit to Earth — meaning that it will be a near-"supermoon," appearing ever-so-slightly larger than usual.
The moon becomes officially full on Monday at 11:32 p.m. EDT (0332 GMT on Tuesday, April 27), according to NASA. In New York City moonrise is at 7:24 p.m. local time on Monday, and moonset is Tuesday morning at 6:26 a.m.; the sun sets Tuesday at 7:49 p.m., according to Time and Date.
The full moon will be in the constellation Libra and have an angular diameter (or apparent width) of 33.41 arcminutes, against an average of 31 arcminutes across, according to Heavens-Above.com calculations. An arcminute is one-sixtieth of a degree, so the difference in size to most people won't be noticeable. The moon reaches perigee the next day — April 27 at 11:23 a.m. EDT (1523 GMT). (The timing will be the same all over the Earth; one need only adjust one's time zone).
The moon appears larger because it is at its closest point to Earth this month, at a distance of 222,064 miles (357,378 kilometers) versus an average of 240,000 miles (384,400 km). The moon's orbit isn't a perfect circle; it's actually an ellipse (though if you were to draw it on a piece of paper to scale it would still look like a circle). When the full moon coincides with perigee it is sometimes called a "supermoon." In this case, the full moon will miss perigee by about 12 hours. "Supermoon" isn't a term used by astronomers, and whether a full moon counts as "super" depends on how close to the official full moon the user of the word thinks perigee should be.
Full moons occur when the moon is on the opposite side of the Earth from the sun. We see the moon's Earth-facing side fully illuminated by the sun, unless the moon's orbit carries it through the Earth's shadow, resulting in a lunar eclipse. That won't happen this time — the moon will "miss" the Earth's shadow because the moon's orbit is inclined 5 degrees to the plane of the Earth's orbit. If an astronaut were standing on the moon, from their perspective the sun would be directly overhead — it would be lunar noontime, with the Earth appearing dark like the new moon, offset from the sun (though invisible except for the city lights on the surface).
When observing the full moon through binoculars or a small telescope it can be hard to spot surface details, because there are no shadows. Moon filters are available that can make some features stand out. Waiting a few days after the full moon or observing a few days before allows shadows to bring out more detail.
Visible planets, stars and constellations
Being in the constellation Libra, the moon will make a rough right triangle with Arcturus, the brightest star in the constellation Boötes, the herdsman, and Spica, the brightest star in Virgo. At about 9:30 p.m. local time in mid-northern latitudes, Arcturus will be to the left (north) of the moon, and Spica is slightly above it to the right as the moon rises in the southeast (the moon would be at the right-angle point of our triangle).
As the full moon becomes visible in the evening, the sun will be just setting and the two will share the sky for about 20 minutes. Among the first objects to become visible after the sun sets will be Mars, high in the south-southwest. By about 9 p.m. on April 26 it will be about 35 degrees above the horizon, in the constellation Gemini. Mars will be above and to the left of the star Aldebaran, and above the constellation of Orion, the hunter. In fact, it will form a bright group with the stars Aldebaran,
Betelgeuse, Procyon and Sirius, the brightest star in the sky — Sirius will be toward the southwest about 13 degrees above the horizon. Bringing your eyes upwards will hit Procyon, the brightest star in Canis Minor, the "little dog," and going down farther you'll spot Betelgeuse. Mars sets by 12:18 a.m. on April 27 in New York City, according to Heavens-Above.com.
Jupiter and Saturn, meanwhile, will be visible in the wee hours; Saturn rises first, at 2:39 a.m. local time on April 27 in New York, and Jupiter follows at 3:20 a.m. local time. Saturn is in the constellation Capricornus and Jupiter in Aquarius, both relatively faint groupings of stars. From mid-northern latitudes, Saturn will appear to the right of Jupiter by about 4 a.m., about 13 degrees above the southeastern horizon. Jupiter will be about 7 degrees above the horizon.
In the Southern Hemisphere, the plane of the Earth's orbit, known as the ecliptic, will meet the horizon at a much steeper angle than in the Northern Hemisphere in the predawn, late-April sky (this is a function of the season; the situation is reversed in September).
If you are in the mid-southern latitudes, Saturn and Jupiter will rise much earlier. In Melbourne, for example, Saturn rises at 12:05 a.m. local time on the morning of April 27 and Jupiter at 1:19 a.m. local time. As a consequence, both will be a lot higher in the sky — by 4 a.m. local time in Melbourne Saturn is a full 45 degrees high and Jupiter is about 31 degrees. (The full moon occurs in Melbourne at 1:31 p.m. on April 27).
The April full moon shares the sky with bright winter constellations, but only briefly, as all but Gemini have set by 10 p.m.; at that point, Leo is high, near the zenith as one faces south, with Virgo (and the moon) to the left. Crossing the sky (though hard to see with a full moon) is the Hydra constellation, a line of medium-to-faint stars that starts to the right of Spica and ends about halfway between Regulus, the brightest star in Leo, and Procyon.
By about midnight on April 26-27 the Summer Triangle, an asterism made up of Vega, Deneb and Altair will be just clearing the horizon in the east from the mid-northern latitudes. Vega is the brightest star in Lyra, the lyre (and made famous by the movie "Contact"). Deneb is the brightest star in Cygnus, the swan (which also forms the Northern Cross) and Altair is the brightest star in Aquila, the eagle.
In mid-southern latitudes by 9 p.m., as the full moon gets higher in the northeast, one can see the constellation Centaurus, the centaur high in the southeast, which contains Alpha Centauri, our nearest stellar neighbor. Above Centaurus and nearly overhead is the Southern Cross, and near the zenith will be Puppis, Carina and Vela, the three constellations that make up the Ship. In the east-southeast, an upside-down Scorpius will be pointing its claws towards the moon, as Antares rises.
How the 'Pink Moon' got its name
According to the Ontario Native Literacy Project, the Ojibwe (Anishinaabe) peoples called it Namebine Giizis, the Sucker Moon, for the eponymous fish, which goes to the spirit world and receives cleansing techniques.
The Haida of the Pacific Northwest call the April full moon Xiit Kungáay, or "Migratory geese moon," according to the Tlingit Moon and Tide Teaching Resource published by the University of Alaska at Fairbanks.
Related: Full moon names (and more) for 2021
In the Southern Hemisphere, April is late summer and early autumn, and the Māori of New Zealand described the lunar month in April to May (as measured between the successive new moons, with the full moon halfway between) as Haratua, which means " Crops are now stored in pits. The tasks of man are finished," according to the Encyclopedia of New Zealand.
In China, the traditional lunar calendar calls the April lunation the third month, Táoyuè, or Peach Month.
For Muslims, the full moon marks the middle of the holy month of Ramadan, when observant Muslims fast from sunrise to sunset until the next new moon.
Editor's note: If you have an amazing skywatching photo you'd like to share for a possible story or image gallery, you can send images and comments in to firstname.lastname@example.org.