The full moon shows its face to Earth about once a month. Yeah, sort of.
Usually the full moon is not perfectly full. We always see the same side of the moon, but part of it is in the shadow. Only when the Moon, Earth, and Sun are perfectly aligned is the Moon 100% full, and that alignment produces a lunar eclipse.
And sometimes – once in a blue moon – the moon is full twice in a month (or four times in a season, whichever definition you prefer).
The next full moon will take place Monday, April 26 at 11:31 PM EDT (3:31 UTC, April 27), but the moon will appear full to the casual stargazer the night before and after its peak. April’s full moon, which will be one of this year’s supermoons, is also referred to as the Pink Moon, although it has many other nicknames by different cultures.
Related: Night Sky, April 2021: What You Can See This Month
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When is the full moon? Calendar dates for 2021
This is when full moons will occur in 2021, according to NASA:
|Date||Name||US Eastern Time||UTC|
|Jan 28||Wolf Moon||2:16 PM||19:16|
|February 27||Snow moon||3:17 pm||8:17|
|Feb 28||Worm Moon||2:48 pm||18:48|
|26 April||Pink Moon||11:31 PM||3:31 (April 27)|
|May 26||Flower moon||7:14 am||11:14|
|Jun 24||Strawberry Moon||2:40 PM||18:40|
|Jul 23||Buck Moon||10:37 am||2:37 (July 24)|
|August 22||Sturgeon Moon||8:02 am||12:02|
|Sep 20, 2019||Corn Moon||7:55 am||23:55|
|20 Oct.||Harvest moon||10:57 am||14:57|
|Nov 19||Beaver Moon||3:58 pm||8:58|
|Dec 18||Cold moon||11:36 pm||4:36 (December 19)|
The 2021 full moon names explained
Many cultures have given different names to each month’s full moon. The names were applied to the entire month in which they occurred. The Farmer’s Almanac lists some names commonly used in the United States. There are some variations in the moon names, but generally the same ones were used by the Algonquin tribes from New England in the west to Lake Superior. European settlers followed their own customs and created some of their own names.
Other Native American people had different names. In the book “This Day in North American Indian History” (Da Capo Press, 2002), author Phil Konstantin lists more than 50 indigenous peoples and their names for full moons. He also lists them on his website, AmericanIndian.net.
Amateur astronomer Keith Cooley has a short list of the moon names of other cultures, including Chinese and Celtic, on his website. For instance,
Chinese moon names:
|January||Holiday moon||July||Hungry Ghost Moon|
|February||Budding moon||August||Harvest moon|
|March||Sleepy moon||September||Chrysanthemum Moon|
|April||Peony Moon||October||Friendly moon|
|May||Dragon Moon||November||White Moon|
|June-||Lotus Moon||December||Bitter Moon|
Full moon names often correspond to seasonal markers, so a harvest moon occurs at the end of the growing season, in September or October, and the cold moon occurs in frosty December. At least that’s how it works in the Northern Hemisphere.
In the Southern Hemisphere, where the seasons are switched, the Harvest Moon falls in March and the Cold Moon in June. According to Earthsky.org, these are common names for full moons south of the equator.
January: Hay Moon, Buck Moon, Thunder Moon, Mead Moon
February (mid summer): Grain Moon, Sturgeon Moon, Red Moon, Wyrt Moon, Corn Moon, Dog Moon, Barley Moon
March: Harvest Moon, Corn Moon
April: Harvest Moon, Hunter’s Moon, Blood Moon
May: Hunter’s Moon, Beaver Moon, Frost Moon
June: Oak Moon, Cold Moon, Long Night’s Moon
July: Wolf Moon, Old Moon, Ice Moon
August: Snow Moon, Storm Moon, Hunger Moon, Wolf Moon
September: Worm Moon, Lenten Moon, Crow Moon, Sugar Moon, Chaste Moon, Sap Moon
October: Egg Moon, Fish Moon, Seed Moon, Pink Moon, Waking Moon
November: Corn Moon, Milk Moon, Flower Moon, Hare Moon
December: Strawberry Moon, Honey Moon, Rose Moon
The phases of the moon explained with dates
The Moon is a sphere that travels around the Earth once every 27.3 days. It also takes about 27 days for the moon to rotate on its axis. So the moon always shows us the same face; there is not a single “dark side” of the moon. As the moon revolves around the earth, it is illuminated from different angles by the sun – what we see when we look at the moon is reflected sunlight. On average, the moon rises about 50 minutes later every day, which means it rises sometimes in daylight and other times at night.
At new moon, the moon is located between the earth and the sun, so that the side of the moon facing us does not receive direct sunlight and is illuminated only by dim sunlight reflected off the earth.
A few days later, as the moon moves around the Earth, the side we can see becomes gradually more illuminated by direct sunlight. This thin strip is called the waxing crescent moon.
A week after the new moon, the moon is 90 degrees from the sun in the sky and is half lit from our point of view – what we call the first quarter, because it is about a quarter of the way around Earth.
A few days later, the lighting area continues to increase. More than half of the moon’s face appears to get sunlight. This phase is called a waxing moon.
When the moon has moved 180 degrees from the new moon phase, the sun, earth, and moon form a line. The moon’s disk is as close as possible to being fully illuminated by the sun, so this is called a full moon.
Then the moon moves until more than half of its face appears to get sunlight, but the amount decreases. This is the waning moon phase.
Days later, the moon has moved another quarter around the earth, to the position of the third quarter. The sun’s light is now shining on the other half of the moon’s visible face.
Then the moon goes into the waning sickle phase, as less than half of its face appears to get sunlight, and the amount decreases.
Finally, the moon returns to the starting position of the new moon. Because the moon’s orbit is not exactly in the same plane as the Earth’s orbit around the sun, they are rarely perfectly aligned. Usually the moon will pass above or below the sun from our vantage point, but occasionally it will pass right in front of the sun and we get a solar eclipse.
Each full moon is calculated to occur at an exact moment, whether or not near the time the moon rises where you are. So when a full moon comes up, it usually happens several hours before or after the actual time when it’s technically full, but a casual skywatcher won’t notice the difference. In fact, the moon will often look similar on two consecutive nights around the full moon.
Lunar eclipses of 2021
Lunar eclipses are inextricably linked to the full moon.
When the Moon is in its full phase, it passes behind the Earth with respect to the Sun and can pass through Earth’s shadow, creating a lunar eclipse. When the moon is completely in the shadow of the Earth, we see a total lunar eclipse. At other times, the moon only partially passes through Earth’s shadow in what is known as a partial or even penumbral lunar eclipse (when the moon only passes through the outermost part of Earth’s shadow).
There will be two lunar eclipses in 2021. A total lunar eclipse will occur on May 26 and a partial lunar eclipse on November 19.
The May 26 total lunar eclipse will only be visible in parts of East Asia, Australia, the Pacific, and the Americas. It starts at 4:47 am EDT (0847 GMT) and ends at 9:49 am EDT (1349 GMT).
The partial lunar eclipse of November 19 will be visible in the early morning hours in the Americas, Northern Europe, East Asia, Australia and the Pacific. It starts at 1:02 am EST (0602 GMT) and ends at 7:03 am EST (1203 GMT).
Because the moon’s orbit is tilted around the Earth, it does not align with the Earth’s shadow every month, and we do not have a lunar eclipse every month.
Solar eclipses of 2021
When the moon is in its “new” phase, it moves between the earth and the sun, so that the side facing the earth appears dark.
Occasionally, the moon’s orbit gets so far away with the sun that part or all of the sun can be blocked by the moon, as seen from Earth. When the moon completely blocks the solar disk, we see a total solar eclipse during the day, which can be a truly awe-inspiring place. Other times, the moon can only partially block the sun in a partial eclipse.
The moon can even create a “ring of fire” eclipse when it passes directly in front of the sun, but is at a point in its orbit that is too far from Earth to completely cover the solar disk. This leaves a ring or “annulus” around the moon to create what is called an annular solar eclipse.
There will be two solar eclipses in 2021. An annular solar eclipse “ring of fire” will occur on June 10, 2021. It will be visible as a partial solar eclipse from regions in North America, Europe and Asia, with the “ring of fire”. effect visible from Northern Canada, Greenland and Russia.
The 2021 total solar eclipse will occur on December 4. It will only be visible in its entirety from Antarctica, with partial views from South Africa and the South Atlantic.