March 2021: The Next Full Moon is the Worm Moon (and, By Some Definitions, a Supermoon)

The next full Moon will be Sunday afternoon, March 28, 2021, appearing opposite the Sun in Earth-based longitude at 2:48 PM EDT. This will be on Monday morning from India's timezone eastward to the International Date Line. The Moon will appear full for about three days around this time, from Saturday morning through Monday night into early Tuesday morning.

In the 1930s the Maine Farmer's Almanac began publishing American Indian Moon names for each month of the year. According to this almanac, as the full Moon in March this is the Crow, Crust, Sap, Sugar, or Worm Moon. The more northern tribes of the northeastern United States knew this as the Crow Moon, when the cawing of crows signaled the end of winter. Other northern names were the Crust Moon, because the snow cover becomes crusted from thawing by day and freezing by night, or the Sap (or Sugar) Moon as this is the time for tapping maple trees. The tribes more to the south called this the Worm Moon after the earthworm casts that appear as the ground thaws. It makes sense that only the southern tribes called this the Worm Moon. When glaciers covered the northern part of North America they wiped out the native earthworms. After these glaciers melted about 12,000 years ago the more northern forests grew back without earthworms. Earthworms in these areas now are mostly invasive species introduced from Europe and Asia.

In the Hebrew calendar the months change with the new Moon and full Moons fall in the middle of the lunar months. This full Moon is in the middle of Nisan, which corresponds with Pesach or Passover. This year Pesach begins at sundown on March 27, and ends at nightfall on April 4, 2021.

In the western Christian ecclesiastical calendar this is the Paschal Moon, from which the date of Easter is calculated. Paschal is the Latinized version of Pesach. Generally, the Christian holiday of Easter, also called Pascha, is celebrated on the first Sunday after the first full Moon of spring. However, there are differences between the times of these astronomical events and the different calendars used by the Eastern and Western churches. This is one of the years where it makes a difference. Western Christianity will be celebrating Easter on Sunday, April 4, 2021, the Sunday after this first full Moon of spring. Eastern Christianity will be celebrating the full Moon after next as the Paschal Moon and Eastern Orthodox Easter will be celebrated on Sunday, May 2, 2021.

Updating the tradition of naming Moons after prominent phenomena tied to the time of year, two years ago my friend Tom Van Wagner suggested naming this the Pothole Moon. Perhaps it is less driving due to the pandemic, but in my area, at least, I've not been running into as many potholes this year as in previous years...

As the full Moon in the Hindu month Phalguna, this Moon corresponds with the Holi festival, celebrating the victory of good over evil and the start of spring. Among other things, Holi includes a free-for-all game involving the spraying of colored powders and/or colored water on whomever wanders by. In 2021, Holika Dahan will be on March 28 and Holi on March 29.

Every full Moon is a holiday in Sri Lanka. This full Moon is Medin or Madin Poya, marking the Buddha’s first visit to his father after his enlightenment.

In the Chinese lunisolar calendar the months change with the new Moon and full Moons fall in the middle of the lunar months. This full Moon is in the middle of the second month of the Chinese calendar.

In the Islamic calendar the months start with the first sighting of the waxing crescent Moon shortly after the New Moon. This full Moon is near the middle of Sha'ban, the month before Ramadan and the eighth month of the calendar. Moslems celebrate the 15th day of Sha'ban as Shab-e-Barat or Bara'at Night. Shia Muslims also celebrate this as Mid-Sha'ban. This year Shab-e-Barat is expected to start at sundown on March 28 and end at sundown on March 29, 2021.

The term "supermoon" was coined by the astrologer Richard Nolle in 1979 and refers to either a new or full Moon that occurs when the Moon is within 90% of perigee, its closest approach to Earth. Supermoons have become popular over the last few decades. Depending upon how you interpret this definition, in a typical year there can be 2 to 4 full supermoons in a row and 2 to 4 new supermoons in a row. Since we can't see a new Moon (except where it eclipses the Sun), what catches the public's attention are the full supermoons, as this is when the full Moon appears near its biggest and brightest for each year. Different publications use slightly different thresholds for deciding when a full Moon is close enough to the Earth to qualify as a supermoon. For 2021, some publications consider the four full Moons from March to June, some the three full Moons from April to June, and some only the two full Moons in April and May as supermoons. The full Moons in April and May are nearly tied as the closest full Moons of the year. The full Moon on May 26, 2021, will be slightly closer to the Earth than the full Moon on April 26, 2021, but only by a slim 0.04%!

As usual, the wearing of suitably celebratory celestial attire is encouraged in honor of the full Moon. See if you notice more crows cawing, earthworm casts, or potholes, and celebrate the start of spring, perhaps with some colorful displays (although I don't recommend spraying strangers with colors unless you are in an area where everyone is expecting it because of Holi).

Here is a summary of celestial events between now and the full Moon after next (with times based on the location of NASA Headquarters in Washington, DC):

As spring begins in the northern hemisphere the daily periods of sunlight continue to lengthen. On Sunday, March 28, 2021 (the day of the full Moon), morning twilight will begin at 6:00 AM EDT, sunrise will be at 6:59 AM, solar noon will be at 1:12:58 PM when the Sun will reach its maximum altitude of 54.40 degrees, sunset will be at 7:28 PM, and evening twilight will end at 8:26 PM. By Monday, April 26, 2021 (the day of the full Moon after next), morning twilight will begin at 5:14 AM, sunrise will be at 6:16 AM, solar noon will be at 1:05:48 PM when the Sun will reach its maximum altitude of 64.87 degrees, sunset will be at 7:56 PM, and evening twilight will end at 8:59 PM.

On the evening of Sunday, March 28, 2021, (the day of this full Moon), as evening twilight ends (at 8:26 PM EDT), the only visible planet in the sky will be Mars, appearing about 51 degrees above the western horizon. The bright star appearing closest to directly overhead will be Pollux at 79 degrees above the southern horizon. The bright stars of the local arm of our home galaxy including the constellation Orion will appear spread from the south up towards Mars. Sirius, the brightest of the stars in our sky (other than the Sun), will appear 33 degrees above the horizon in the south-southwest.

As the lunar cycle progresses, the planet Mars and the background of stars will appear to shift towards the west (although it is actually the Earth that is moving around the Sun towards the east). Mars will appear to shift more slowly than the stars (since Mars is moving around the Sun in the same direction as Earth). April 20, 2021, will be the first evening that the bright planet Venus will be just barely above the horizon in the west-northwest 30 minutes after sunset (an approximation of when Venus will start becoming visible in the evening sky). April 24, 2021, will be the first evening that the planet Mercury will join Venus just barely above the horizon in the west-northwest 30 minutes after sunset (an approximation of when Mercury will start becoming visible in the evening sky).

By the evening of Monday, April 26, 2021, (the day of the full Moon after next), as evening twilight ends (at 8:59 PM EDT), Mars will appear about 38 degrees above the western horizon. Venus and Mercury will have already set, but you might be able to catch them in the glow of dusk from about 30 minutes after sunset until they set in the west northwest. The bright star appearing closest to directly overhead will be Regulus at 63 degrees above the southern horizon. Sirius will appear 16 degrees above the southwestern horizon. The bright stars of the local arm of our home galaxy including the constellation Orion will appear spread along the horizon from the south-southwest towards the west.

On the morning of Sunday, March 28, 2021, (the day of this full Moon), as morning twilight begins (at 6 AM EDT), the bright planet Jupiter will appear 9 degrees above the east-southeastern horizon with the fainter planet Saturn to the upper right at 14 degrees above the southeastern horizon. The bright star appearing closest to overhead will be Vega, one of the three stars in the Summer Triangle, appearing 74 degrees above the eastern horizon. The planet Mercury will be lost in the glow of dawn, rising about 32 minutes before sunrise.

As the lunar cycle progresses, the background of stars and planets will appear to shift towards the west each morning. By the morning of Monday, April 26, 2021, (the day of the full Moon after next), as morning twilight begins (at 5:14 AM EDT), the bright planet Jupiter will appear 18 degrees above the southeastern horizon with the fainter planet Saturn to the upper right at 23 degrees above the southeastern horizon. The bright star appearing nearly overhead will be Vega, one of the three stars in the Summer Triangle, at about 87 degrees above the eastern horizon.

Here is a more detailed, day-by-day listing of celestial events between now and the full Moon after next (again with times based on the location of NASA Headquarters in Washington, DC):

On Monday evening into Tuesday morning, March 22 to 23, 2021, the bright star Pollux, the brighter of the twin stars in the constellation Gemini, will appear above the waxing gibbous Moon. Pollux will appear about 7 degrees to the upper left of the Moon as evening twilight ends (at 8:20 PM EDT), close to when the Moon will be highest in the sky for the night. Pollux will appear about 5 degrees to the upper right of the Moon by the time the Moon sets in the west-northwest on Tuesday morning (at 4:10 AM).

Even though they are not usually visible, I include in these Moon missives information about Near Earth Objects (mostly asteroids) that may pass the Earth within 5 lunar distances, because I find it interesting that we have discovered so many.

On Monday night, March 22, 2021, at about 11:05 PM EDT (2021-Mar-23 03:05 UTC with 5 minutes uncertainty), Near Earth Object (2021 FO1), between 3 and 7 meters (11 to 25 feet) across, will pass the Earth at 0.8 lunar distances traveling at 7.46 kilometers per second (16,680 miles per hour).

On Tuesday afternoon, March 23, 2021, at 12:52 PM EDT (2021-Mar-23 16:52 UTC), Near Earth Object (2021 FH), between 12 and 27 meters (40 to 89 feet) across, will pass the Earth at 0.6 lunar distances traveling at 12.00 kilometers per second (26,840 miles per hour).

On Wednesday morning, March 24, 2021, at about 11:30 AM EDT (2021-Mar-24 15:30 UTC with 11 minutes uncertainty), Near Earth Object (2021 FV), between 5 and 12 meters (17 to 39 feet) across, will pass the Earth at 2.2 lunar distances traveling at 10.59 kilometers per second (23,690 miles per hour).

On Wednesday afternoon, March 24, 2021, sometime around 2 PM EDT (2021-Mar-24 17:53 UTC with 59 minutes uncertainty), Near Earth Object (2021 FK1), between 10 and 23 meters (33 to 74 feet) across, will pass the Earth at between 1.5 and 1.6 lunar distances (nominally 1.5) traveling at 13.51 kilometers per second (30,220 miles per hour).

On Thursday evening into Friday morning, March 25 to 26, 2021, the bright star Regulus will appear about 5 degrees below the waxing gibbous Moon. Regulus will appear to the lower right of the Moon as evening twilight ends (at 8:23 PM EDT). By the time the Moon reaches its highest in the sky for the night (at 11:08 PM) Regulus will appear nearly below the Moon. Regulus will set first in the west-northwest on Friday morning at 5:43 AM.

On Friday morning, March 26, 2021, the planet Venus will be passing on the far side of the Sun as seen from the Earth, called superior conjunction. Because Venus orbits inside of the orbit of Earth, Venus will be shifting from the morning to the evening sky. Venus will begin emerging from the glow of dusk on the western horizon after about April 23, 2021.

On Sunday morning, March 28, 2021, at around 2:14 AM EDT (2021-Mar-28 06:14 UTC with 18 minutes uncertainty), Near Earth Object (2021 FA1), between 5 and 10 meters (15 to 34 feet) across, will pass the Earth at between 3.6 and 3.7 lunar distances (nominally 3.6) traveling at 3.95 kilometers per second (8,830 miles per hour).

As mentioned above, the next full Moon will be Sunday afternoon, March 28, 2021, at 2:48 PM EDT. The Moon will appear full for about 3 days around this time, from early Saturday morning into early Tuesday morning.

On Monday evening, March 29, 2021, the bright star Spica will appear to the right of the full Moon. The Moon will rise in the east about 20 minutes after evening twilight ends with Spica about 7 degrees to the right of the Moon, and the pair will appear to separate as the night progresses.

On Tuesday morning, March 30, 2021, at 2:13 AM EDT, the Moon will be at perigee, its closest to the Earth for this orbit.

On Friday morning, April 2, 2021, the bright star Antares will appear to the right of the waning gibbous Moon. The Moon will rise in the east-southeast after midnight (at 12:33 AM EDT) with Antares about 6 degrees to the right. Antares will appear about 8 degrees to the lower right by the time morning twilight begins.

Sometime around Friday, April 2, 2021 (2021-Apr-02 16:28 UTC with 3 days, 2 hours, 28 minutes uncertainty), Near Earth Object (2021 FT), between 11 and 25 meters (36 to 81 feet) across, will pass the Earth at between 3.3 and 5.2 lunar distances (nominally 4.3), traveling at 5.41 kilometers per second (12,110 miles per hour).

Sunday morning, April 4, 2021, the waning Moon will appear half-full as it reaches its last quarter at 6:02 AM EDT.

In the Chinese lunisolar calendar, Monday, April 5, 2021, marks the start of the Qingming solar term, the fifth solar term of the year. The Chinese lunisolar calendar uses both lunar months and solar terms. The solar terms start at the vernal or spring equinox and divide the solar year into 24 terms. There are two systems, but the more common one starts a new term when the Sun appears to have moved another 15 degrees in celestial longitude around the ecliptic, the Sun's apparent path around the Earth. For over 2,500 years, the Chinese have celebrated the Qingming Festival starting on the first day of Qingming. Called the Tomb-Sweeping Day, this festival is sometimes described as the Chinese Memorial Day or Ancestors' Day.

On Tuesday morning, April 6, 2021, the planet Saturn will appear to the upper left of the waning crescent Moon, with the bright planet Jupiter appearing farther to the left. Saturn will rise first in the east-southeast about 1 hour, 45 minutes before morning twilight begins (at 4:03 AM EDT), the Moon next about 19 minutes later (at 4:22 AM), and Jupiter about 17 minutes after the Moon (at 4:39 AM). The Moon will appear about 12 degrees above the southeastern horizon as morning twilight begins (at 5:45 AM).

On Wednesday morning, April 7, 2021, the waning crescent Moon will have shifted to appear about 5 degrees to the lower right of the bright planet Jupiter, with the planet Saturn farther to the right. The Moon will rise last in the east-southeast about 45 minutes before morning twilight begins (at 4:58 AM EDT). The Moon will appear about 7 degrees above the east-southeastern horizon as morning twilight begins (at 5:44 AM).

Sunday night, April 11, 2021, at 10:31 PM EDT, will be the new Moon, when the Moon passes between the Earth and the Sun and will not be visible from the Earth. The day of or the day after the New Moon marks the start of the new month for most lunisolar calendars. In the Hebrew calendar, sundown on Sunday, April 11, 2021, will mark the start of Iyar. The third month of the Chinese year of the Ox starts on Monday, April 12, 2021 (at midnight in China's time zone, which is 12 hours ahead of EDT).

In the Islamic calendar the months start with the first sighting of the waxing crescent Moon. Many Muslim communities now follow the Umm al-Qura Calendar of Saudi Arabia, which uses astronomical calculations to start the months in a more predictable way (intended for civil and not religious purposes). Because of its religious significance, Ramadan is one of 4 months in the Islamic year where the start of the month is updated in the Umm al-Qura Calendar based upon the actual sighting of the crescent Moon. This calendar predicts the holy month of Ramadan may start with sunset on Monday, April 12, 2021, but the actual start will be adjusted based on observations of the crescent Moon. Ramadan is honored as the month in which the Quran was revealed. Observing this annual month of charitable acts, prayer, and fasting from dawn to sunset is one of the Five Pillars of Islam.

In India's time zone, Tuesday, April 13, 2021, marks the start of Chaitra, the first month of the Hindu lunisolar religious calendar. The first of Chaitra is celebrated as New Year's Day and is known as Gudi Padwa in Maharashtra, Chaitrai Vishu or Puthandu in Tamil Nadu and Ugadi in Karnataka and Andhra Pradesh. This starts the 9-day New Years celebration called Chaitra Navratri. These nine days are dedicated to forms of the Goddess Shakti. Many of the customs and rituals followed during Chaitra Navratri are similar to those for the fall celebration called Shardiya Navratri (in September or October). Chaitra Navratri ends with Rama Navami on April 21, 2021, celebrating the birthday of Lord Rama, so Chaitra Navratri is also called Rama Navratri.

Wednesday afternoon, April 14, 2021, at 1:48 PM EDT, the Moon will be at apogee, its farthest from the Earth for this orbit.

On Thursday evening, April 15, 2021, the bright star Aldebaran will appear about 6 degrees to the left of the waxing crescent Moon. The pair will appear about 26 degrees above the western horizon as evening twilight ends (at 8:46 PM EDT). Aldebaran will set first in the west-northwest a little more than 2.5 hours later (at 11:05 PM).

On Friday evening, April 16, 2021, the planet Mars will appear about 7 degrees above the waxing crescent Moon. The Moon will appear about 37 degrees above the western horizon as evening twilight ends (at 8:47 PM EDT). The Moon will set first in the west-northwest a little more than 3.5 hours later (Saturday morning at 12:18 AM).

By Saturday evening, April 17, 2021, the waxing crescent Moon will appear to have shifted to the other side of the planet Mars. The Moon will appear about 47 degrees above the western horizon as evening twilight ends (at 8:48 PM EDT) with Mars appearing about 7 degrees to the lower right of the Moon. Mars will set first in the northwest a little less than 4 hours later (Sunday morning at 12:39 AM). The Moon and Mars appeared at their closest together on Saturday morning when they appeared on the other side of the Earth.

On Sunday evening, April 18, 2021, the planet Mercury will be passing on the far side of the Sun as seen from the Earth, called superior conjunction. Because Mercury orbits inside of Earth, Mercury will be shifting from the morning sky to the evening sky and will begin emerging from the glow of dusk on the western horizon later in April (depending upon viewing conditions).

On Monday evening into early Tuesday morning, April 19 to 20, 2021, the bright star Pollux will appear to the right of the waxing half Moon. Pollux will appear about 5 degrees to the right as evening twilight ends (at 8:51 PM EDT). The pair will appear to separate as the night progresses, with Pollux setting in the northwest on Tuesday morning about 6 minutes before moonset (at 2:45 AM).

Early Tuesday morning, April 20, 2021, the Moon will appear half-full as it reaches its first quarter at 2:59 AM EDT (about 8 minutes after moonset for the Washington, DC area).

Tuesday evening, April 20, 2021, will be the first evening that the bright planet Venus will be just barely above the horizon in the west-northwest 30 minutes after sunset (an approximation of when Venus will start becoming visible in the evening sky).

Wednesday evening into Thursday morning, April 21 to 22, 2021, the bright star Regulus will appear to the lower left of the waxing gibbous Moon. Regulus will be about 8 degrees to the lower left as evening twilight ends (at 8:53 PM EDT), when the Moon will be near its highest in the sky for the evening. The pair will appear to shift closer together and reach about 6 degrees apart as Regulus sets in the west-northwest Thursday morning (at 3:57 AM).

The annual Lyrid meteor shower is expected to peak early in the morning on Thursday, April 22, 2021. This year, the light of the waxing gibbous Moon will interfere with the visibility of these meteors, which under ideal conditions (which we don't have this year) might be expected to produce about 18 visible meteors per hour. On the morning of April 22 the Moon will set about 30 minutes before any sign of dawn begins to show in the east (at 4:07 AM and 4:44 AM EDT, respectively), so there will only be a short window without light interference.

Saturday evening, April 24, 2021, will be the first evening that the planet Mercury will join Venus just barely above the horizon in the west-northwest 30 minutes after sunset (an approximation of when Mercury will start becoming visible in the evening sky).

Sunday evening into Monday morning, April 25 to 26, 2021, the bright star Spica will appear near the full Moon. As evening twilight ends (at 8:58 PM EDT) the Moon will appear about 27 degrees above the horizon in the east-southeast, with Spica about 7 degrees to the lower right. The Moon will reach its highest in the sky for the night on Monday morning just after midnight (at 12:19 AM), with Spica about 6 degrees below the Moon. As morning twilight begins on Monday morning (at 5:14 AM), the Moon will appear about 9 degrees above the horizon in the west-southwest with Spica about 5 degrees below the Moon.

Sometime around Monday, April 26, 2021 (2021-Apr-26 13:05 UTC with 4 days, 14 hours, 59 minutes uncertainty), Near Earth Object (2015 HA177), between 8 and 17 meters (25 to 56 feet) across, will pass the Earth at between 0.8 and 47.4 lunar distances (nominally 18.6), traveling at 8.71 kilometers per second (19,480 miles per hour).

Also sometime around Monday, April 26, 2021 (2021-Apr-26 22:24 UTC with 7 days, 20 hours, 11 minutes uncertainty), Near Earth Object (2019 HF4), between 8 and 18 meters (26 to 59 feet) across, will pass the Earth at between 1.2 and 18.4 lunar distances (nominally 7.7), traveling at 6.76 kilometers per second (15,120 miles per hour).

The full Moon after next will be Monday night, April 26, 2021, appearing opposite the Sun at 11:31 PM EDT. The Moon will appear full for about 3 days around this time, from Sunday evening through Wednesday morning.

The term "supermoon" was coined by the astrologer Richard Nolle in 1979 and refers to either a new or full Moon that occurs when the Moon is within 90% of perigee, its closest approach to Earth.

Supermoons have become popular over the last few decades. Depending upon how you interpret this definition, in a typical year there can be 2 to 4 full supermoons in a row and 2 to 4 new supermoons in a row.

Since we can't see a new Moon (except where it eclipses the Sun), what catches the public's attention are the full supermoons, as this is when the full Moon appears near its biggest and brightest for each year.

Different publications use slightly different thresholds for deciding when a full Moon is close enough to the Earth to qualify as a supermoon.

For 2021, some publications consider the four full Moons from March to June, some the three full Moons from April to June, and some only the two full Moons in April and May as supermoons.

The full Moons in April and May are nearly tied as the closest full Moons of the year. The full Moon on May 26, 2021, will be slightly closer to the Earth than the full Moon on April 26, 2021, but only by a slim 0.04%!

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