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👩‍🎓 | "Pink Moon" 4/27, full moon in eastern Japan

Area where you can see the photo "Pink Moon"

"Pink Moon" 4/27, full moon in eastern Japan

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It is the first time in about 2018 years since July 7 that a total lunar eclipse has been seen in Japan.

April 2021, 4 is the full moon called "Pink Moon".According to Weathernews, tonight will be centered around eastern Japan ... → Continue reading


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Lunar eclipse

Lunar eclipse[1](Lunar eclipse,English: lunar eclipse[1]What is地球 (I.e.とMonthEnter between and of the earth影It is a phenomenon in which the moon appears to be missing when it is applied to the moon.

Lunar eclipseMay be written as.

Nozomi (full moon) Occurs.eclipseUnlike the place where the moon can be seen, it can be observed and observed from anywhere on the earth at the same time.


All partsHonkageWhen entering (the part where the sun is completely hidden by the earth)Total lunar eclipse(totally eclipse), When only a part is in the main shadowPartial lunar eclipse(partial eclipse).

the moon半影The state of being in (the part where the earth hides a part of the sun)Penumbra food(OrHalf shadow lunar eclipse,penumbral eclipse), But the degree of dimming of the lunar surface in the penumbra can only be known by careful observation, so without prior notice.Naked eyeIn many cases, you will not notice it even if you look at it.

How much the moon is hidden by the shadow of the earthServingIt is calculated by the formula "(radius of the main shadow + radius of sight of the moon-distance between the center of the main shadow and the center of the moon) ÷ (diameter of the moon)".A total lunar eclipse is 1 or more, a partial lunar eclipse is 0-1 and a penumbra eclipse is a negative value.

By the atmosphere of the earthLightOut ofwavelengthLong red lightrefraction・ Because it is scattered and enters the main shadow, the moon usually does not become pitch black even with a total lunar eclipse, and it is dark red (Red bronzeLooks like color).HoweverVolcanoWhen a large amount of fine particles are suspended in the atmosphere due to an explosion or the like, the moon becomes very dark and gray or almost invisible.The brightness at the time of the lunar eclipse is the "dungeon scale" described later (Latter sectionSee) and so on.

In addition, the missing moon in the middle of the lunar eclipse will riseMoon eclipseOn the contrary, the moon that remains lacking will setMoon eclipse(OrMonthly eclipse).

Progress of lunar eclipse

First contact
The moment when the moon begins to enter the true shadow of the earth.
First contact
The moment when the moon completely enters the true shadow of the earth.This momentCentral eclipseIt will be the beginning of.
Maximum food
The time when the angular distance between the center of the moon and the center of the main shadow cone becomes the minimum.
First contact
The moment when the moon begins to emerge from the true shadow of the earth.This moment is the end of the central diet.
First contact
The moment when the moon completely emerges from the true shadow of the earth.


The lunar eclipse occurs in the sun and moonecliptic-White roadIntersection point (Lunar node / descending node) Only when you are in the vicinity.

Lunar eclipses often occur twice or not a year, and sometimes three times a year.21st centuryIn 100 years, a total of 142 times (total lunar eclipse 85 times, partial lunar eclipse 57 times) occur.on the other hand,eclipseA total of 2 times (5 total solar eclipses, 21 annular eclipses, 100 total solar eclipses, 224 partial solar eclipses) in the 68 years of the 72st century, with a minimum of 7 times a year and a maximum of 77 times.Therefore, the frequency of lunar eclipses is lower than that of solar eclipses.[Note 1]..Nevertheless, the lunar eclipse is usually more often seen than the solar eclipse.this isMonthThis is because the lunar eclipse can be observed from anywhere on the earth as long as the lunar eclipse can be seen, whereas the solar eclipse can be seen only in a limited band-shaped area where the shadow of the moon crosses the earth's surface.[Note 2].

The reason for the difference in the frequency of lunar eclipses and solar eclipses can be explained as follows.地球と(I.e.Suppose a huge cone inscribed together.The part where the moon is opposite to the sun in this cone (of the earth)Honkage) Will cause a lunar eclipse, and entering the part in the same direction as the sun will cause a solar eclipse.[Note 3]..Of this coneLunar orbitThe radius in the vicinity is about 4460-4750km on the lunar eclipse side.[Note 4], The eclipse side is about 7990-8280km[Note 5]The frequency of lunar eclipses is lower than that of solar eclipses.

The year when the lunar eclipse was seen (seen) three times a year

Dates seen (seen) on land in Japan (including islands) are written in italics for partial lunar eclipses and in bold for total lunar eclipses.

1833(Tempo3 years leap)
May 1(Tempo 2 yearsLeap February 11) - May 7(Tempo 3 yearsMay 5.Japan time : May 7(May 5))- May 12(November 11, Japan time:May 12(May 11))
1852(Kaei4 years)
May 1(Kaei 4 yearsMay 12) - May 7(Kaei 5 yearsMay 5) - December 12th (November 26th)
1898(Meiji31 years)
May 1(Japan time : May 1)- May 7(Japan time:May 7)- May 12(Japan time:May 12)
1917(Taisho6 years)
May 1 --July 7 (Japan time:May 7)- May 12
1982(Showa57 years)
May 1(Japan time:May 1) - May 7 - May 12
May 1 - July 7 (Japan time:May 7) - May 12(Japan time:2029May 1)
July 1 (Japan time:May 1) - May 6 - May 12(Japan time:May 12)
Besides in Japan2010(Heisei22 years) (May 1,May 6,May 12)was there.
Year without lunar eclipse
1966 - 1969 - 1980 - 1984 - 1998 - 2002 - 2016 - 2020

Observations in Japan

Recently seen lunar eclipse

DateTypesDetailed explanation of the lunar eclipse phenomenon
2000May 7[2]Total 
2001May 1[3]
2001May 7[4]section
2004May 5[3]Total
2005May 10[3]section
2006May 9[3]
2007May 3[3]Moon eclipse
2007May 8[3]TotalMoon eclipse
2008May 8[3]section 
2010May 1[3]
2010May 6[3]
2010May 12[3]Total
2011May 6[3]
2011May 12[3]Another clausereference
2012May 6[3]section 
2014May 4[3]
2014May 10[3]Total
2015May 4[3]
2017May 8[3]section
2018May 1TotalAnother clausereference
2018May 7[3]Moon eclipse
2021May 5[3]Another clausereference

Lunar eclipse to be seen in the future

DateTypesDetailed explanation of the lunar eclipse phenomenon
2021May 11sectionUp to about 98%, monthly eclipse outside Hokkaido and Tohoku regions[3]
2022May 11TotalObserved all over Japan, during a lunar eclipseUranus食Also happens[3]
2023May 10sectionUp to about 10%[3]
2025May 3sectionTotal lunar eclipse, but in Japan only partial eclipse can be seen in Hokkaido[3]
2025May 9TotalObserved all over Japan, total continues for about 1 hour and 24 minutes[3]

Dungeon scale

The appearance of the lunar surface during a total lunar eclipse depends on the amount of dust in the Earth's atmosphere.With less dust, the sun's rays are less scattered as they pass through the atmosphere, and the lunar surface looks yellowish and bright.Conversely, a lot of dust causes more scattering in the atmosphere and the lunar surface looks dark (it is known that in the case of a large-scale volcanic eruption, the lunar surface becomes dark due to the volcanic ash in the atmosphere).French astronomerAndre dungeon 20st centuryEarly on, he set his own scale to classify the brightness of the lunar eclipse.Also commonly referred to as the "dungeon scale".

scaleState of the moon
0Very dark lunar eclipse.I can't see the center of the moon.
1Dark lunar eclipse.It is gray or brown, and the details of the moon are difficult to see.
2A dark red or red rusty lunar eclipse.The center of the moon is very dark and the periphery is a little bright.
3Brick-colored lunar eclipse.The edges of the moon are bright or yellow.
4Very bright lunar eclipse.The edges of the moon are bluish and very bright.

The sun seen from the moon during a lunar eclipse

If you look at the sun from the moon during a lunar eclipse, it should look like the sun is hidden by the earth, like a solar eclipse seen from the earth.2009May 2, Japan's lunar orbiting satelliteKaguyaSucceeded in shooting this scene for the first time in the world.The sun was not completely hidden because it was taken from the penumbra, but the Earth's "Diamond ringWas observed[5].


[How to use footnotes]

注 釈

  1. ^ However, including 86 eclipses of the penumbra, the number of lunar eclipses that occur during this century is 228, which is almost the same frequency as the solar eclipse.
  2. ^ It is said that the total solar eclipse can be observed at one fixed point on the earth once every 1 to 300 years.
  3. ^ If a part of the moon is inside the cone, it is a partial lunar eclipse or a partial solar eclipse, and if the whole moon is inside the cone, it is a total lunar eclipse or a total solar eclipse or an annular solar eclipse.
  4. ^ The viewing angle of the lunar eclipse side cone radius is 0 ° 37'38 "-0 ° 45'45", the lateral weft difference limit of the total lunar eclipse is ± 0 ° 22'58 "-± 0 ° 29'1", and the partial moon. The lateral weft difference limit of the eclipse is ± 0 ° 52'18 "-± 1 ° 2'28".Nozomi, that is, the lunar eclipse limit is ± 4 ° 15'50 "-± from the ascending or descending node of the sun because the lunar eclipse is within this range at the time of the full moon. 5 ° 23'24 ", ± 9 ° 44'58" for partial lunar eclipse-± 11 ° 40'10 ".On the other hand, the ecliptic longitude from the sun's ascending node changes by an average of 1 ° 30'40 "during one lunar month (from one full moon to the next), which is more than twice the lunar month difference limit and one lunar month. It is possible that the sun will pass through the ecliptic limit near the ascending node during the lunar month. In this case, the lunar month will not occur despite the ecliptic season.
  5. ^ The viewing angle of the radius of the cone on the solar eclipse side is 1 ° 9'22 "-1 ° 17'28", and the lateral latitude difference limit of the total / annular solar eclipse is ± 0 ° 54'42 "-± 1 ° 0'44", The lateral latitude difference limit of the partial solar eclipse is ± 1 ° 24'2 "-± 1 ° 34'12".The ecliptic limit is ± 10 ° 11'57 for the total / annular solar eclipse from the ascending or descending node of the sun because the ecliptic latitude of the moon is within this range at the time of the new moon, that is, the new moon. "-± 11 ° 20'29", ± 15 ° 47'13 for partial solar eclipse "-± 17 ° 45'26".Since the ecliptic limit range of the partial solar eclipse is always larger than the amount of movement of the sun during one lunar month, it is possible that at least one partial solar eclipse occurs during the eclipse season, and it is possible to occur twice.


  1. ^ a b "Oxford Astronomy Dictionary" Asakura Shoten, First Edition, First Edition, p. 1.ISBN 4-254-15017-2.
  2. ^ Let's see the total lunar eclipse of July 2000-7, 16 --Atsugi City Children's Science Museum
  3. ^ a b c d e f g h i j k l m n o p q r s t u v w x List of lunar eclipses that can be seen in Japan --Kurashiki Science Center
  4. ^ Let's see the partial lunar eclipse of July 2001-7, 5 --Atsugi City Children's Science Museum
  5. ^ JAXA --Successful shooting of the earth during a penumbra lunar eclipse with a high-definition camera (HDTV) of the lunar orbiting satellite "KAGUYA (SELENE)" --Japan Aerospace Exploration Agency February 2009, 2

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