The penumbral lunar eclipse islunar eclipseAs the sun is a huge light source, the shadow behind the earth will be divided into the umbra area and penumbra area. When the moon only enters the penumbra area of the earth, the so-called "penumbra eclipse" will occur.[22]The moon passes through the earth during its revolution around the earthPenumbraBut it has not passed the earthUmbraA special kind ofAstronomical phenomenon。[1-2]
MoonWhen entering the penumbra of the earth, part of the light from the sun to the moon is blocked by the earth, and the moon looks darker than usual.If you use a telescope to observe the moon, the feeling of darkening will be more obvious.When a penumbral eclipse occurs, onlyFood pointsIf it is greater than 0.7, it can be detected by the naked eye.[3]There are about 89 penumbral lunar eclipses every century.[4]
On March 25, 2024, the penumbra lunar eclipse appeared.[23]
A shadow area, calledGround shadow。The ground shadow is divided intoUmbraandPenumbraTwo parts.The umbra refers to not being affectedsunlightThe penumbra is only partially exposedDirect sunlightLight.At the location of the moon, the radius of the Earth's umbra is about 1.3 times the diameter of the moon, and the radius of the Earth's penumbra is about 2.3 times the diameter of the moon.[2]MoonIn the process of circling the earth, it sometimes enters the shadow of the earth. The sun, the earth and the moon are almost in the same linestraight lineAt this timelunar eclipsePhenomenon.
becauseBai DaoThere is an included angle of about 5.2 ° with the ecliptic plane. Only when the moon is in orbitAscending intersectionorDescending pointAnd when the moon is full, an eclipse will occur.[2]Therefore, the occurrence of lunar eclipse also has a certain periodicity, which is affected byphase of the moonChange period (29.530589 days) andNode month(27.212221 days) modulation, calledSaro period（Saros）。The Shara cycle was first established by the ChaldeanseclipseThe occurrence record summarizes that it is about 6585.32 days, that is, 223 times of the lunar phase period, which is about 242 times of the intersection month.The lunar eclipses with arbitrary intervals of one Saro cycle have similar characteristics（Earth Moon Distance, type of intersection, etc.), and each series of lunar eclipses with similar characteristics forms a Saros Series.Because the Saro cycle is not exactly the lunar phase cycle and the intersection monthLeast common multipleTherefore, every Saro sequence is finite.[5]
Lunar eclipse simulation diagram
When the whole moon enters the umbralunar eclipse；When only part of the moon enters the umbrapartial lunar eclipse。Sometimes the moon does not enter the umbra but only enters or partially enters the penumbra, which is called penumbra eclipse.During the penumbral eclipse, the moon will be slightly darker, but its edge will not be blocked by the shadow of the Earth and become significantly darker.The degree of penumbral eclipse can be expressed by the penumbral magnitudeFood pointsSimilarly, it describes the extent to which the diameter of the moon is obscured by the Earth's penumbra when the penumbra eclipse is severe.
process
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A complete penumbral eclipse can be divided into three stages:
one
Beginning of penumbra eclipse: the moon starts to contact the penumbra area of the earth, and the moon surface and the penumbra of the earthCircumscribe。The brightness of the moon began to decrease slowly, which was difficult to detect with the naked eye.
two
Penumbra eclipse: the moment when the center of the lunar circle is closest to the center of the Earth's umbra.The brightness of the moon drops to the lowest value in the process.
three
The end of penumbra eclipse: the moon leaves the penumbra area of the earth, and the moon surface is circumscribed with the penumbra of the earth.The whole eclipse process officially ended, and the moon brightness returned to normal.
Schematic diagram of penumbra lunar eclipse process
Observation and phenomenon
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Phenomenon description
When the penumbra eclipse occurs, the moon becomes slightly darker, which is more obvious in the telescope
And the eclipse of the umbra（lunar eclipseandpartial lunar eclipse）When the moon is obviously missing, the difference is that when the "penumbra eclipse" occurs, the moon is still round with the naked eye, and still bright, but slightly dim.During the penumbra lunar eclipse, the sunlight projected on the lunar surface is partially blocked by the earthRadial striationOfMeteorite craterIt will be clearer.[6]But also because the sunlight at the penumbra cannot be completely covered, there is noAstronomical observationExperienced people may not be able to see the changes in light and shade of the moon surface caused by the penumbra lunar eclipse.Penumbral lunar eclipses with a penumbral eclipse score greater than 0.7 can be seen by the naked eye, penumbral lunar eclipses with a penumbral eclipse score between 0.4-0.7 are difficult to see by the naked eye, and penumbral lunar eclipses with a penumbral eclipse score less than 0.4 cannot be seen by the naked eye, and must be usedAstronomical telescopeCan be seen.[3]
Many multimedia organizations regard the picture of the total lunar eclipse as the picture of the penumbra lunar eclipse, which is eye-catching and highly misleading to the general public.In fact, the penumbra eclipse is moreAcademic valueRather than ornamental value,Not recommendedObservations by the general public or beginners in astronomy.[7]
Observation mode
Since the phenomenon of penumbra lunar eclipse is not particularly obvious, we usually choose a sunny weather for observationlight pollutionIn low places, city lights and clouds greatly affect observation.Observing with the naked eye, we can see that the moon has a process of darkening and then brightening.General penumbra lunar eclipse is more suitable for useAstronomical telescopeWhen observing, the feeling of the moon darkening will be more obvious, and you can see more details of the moon surface.Photographers can use professional photographic equipment to connect astronomical telescopes to take pictures of the whole penumbra lunar eclipse, so that the brightness changes of the moon before and after the penumbra lunar eclipse can be seen more clearly.
Observation record
There have been many penumbral lunar eclipses in recent years. The following lists the observation records of most penumbral lunar eclipses from 2009 to 2020 by year.
2009
Penumbra eclipse photograph
There were three penumbral lunar eclipses in 2009.The penumbra lunar eclipse on February 9 in ChinaObservation conditionsYes, the penumbra lunar eclipse on August 6 was only in Xinjiang andTibetYou can see it in the westMoon setting with eclipse。February 9 happens to be the 15th day of the first monththe lantern festival, 20:37 that nightPenumbral eclipseAt the beginning, at 22:28, the penumbral eclipse was 0.92.At this time, when you are holding a lantern to watch the moon, you can observe whether the moon is much darker.The penumbra ended at 0:40 the next day.[8]
November 28, 2012October in the lunar calendar15、 When the public appreciatesfull moonAt the same time, a penumbra lunar eclipse is also happening quietly.Astronomy education expertsTianjin Astronomical Society directorZhao ZhihengAccording to the introduction, the penumbra eclipse started at 20:13 on the 28th and ended at 0:53 on the 29th, Beijing time. The whole process can be seen in China. The penumbra eclipse appeared around 22:33, which is the most appropriate time to observe the slightly dim moon.[6]
2013
On May 25, 2013, there was a penumbral lunar eclipse of 0.0157, which was almost invisible.[9]
On October 19, 2013, on the 15th day of the ninth lunar month, the penumbra lunar eclipse started at 5:48 a.m.At this time, the height of the moon in most parts of China has dropped very low, and the observation conditions in the western region are better;The penumbra eclipse occurred at around 7:50, when the moon had set in most parts of China, which was difficult to observe;At 9:52, the penumbra ended.[10]
2016
On the evening of March 23, 2016, there was a penumbral lunar eclipse in the sky, which was visible in most parts of China.[11]
On the Mid Autumn Festival in 2016, the moon will appear at its fullestAugust in the lunar calendar17、 At 3:05 a.m. on September 17, the roundest Mid Autumn Moon can be seen all over China.In addition, at this time, all parts of China can witness the whole process of penumbra lunar eclipse.The penumbra lunar eclipse began at 0:53 a.m. on September 17;2:54 PenumbraFood pointsIs 0.933;At 4:56, the penumbra ended, lasting 4 hours and 03 minutes.With the help of the digital camera's telephoto lens to take pictures in stages or use telescopes to observe the brightness changes on the moon surface.[12]
2017
2017 penumbra lunar eclipse
On February 11, 2017, during the Lantern Festival, the penumbra lunar eclipse also appeared on that day.However, this penumbral eclipse started at 6:34 a.m. and ended at 10:53 a.m., and China can only see eclipses.[13]
2020
In 2020, there will be four penumbral lunar eclipses, three of which will be visible in China.
At 1:07:45 in the morning of January 11, Tianyu began a penumbra lunar eclipse at 0.8956. The penumbra eclipse was at 3:22:27. The lunar eclipse ended at 5:12:19. The whole process can be seen in China.[14]
In the early morning of June 6, there will be a "penumbra lunar eclipse" in Tianyu, and the whole process can be seen in China.The eclipse of the penumbra was less than 0.6. The eclipse began at 1:43 and ended at 5:7 on the 6th. The whole process lasted more than three hours.The eclipse occurred at about 3:25, when it was the most appropriate time to observe the slightly dim moon.[15]
The penumbra lunar eclipse on July 5 is divided into 0.3546 penumbra lunar eclipse, which is invisible to China and invisible to the naked eye.[16]
November 30 is the last penumbral lunar eclipse of this year, and the eclipsed moon can be seen all over the country.The penumbral eclipse started at about 15:30, reached 17:42, and ended at 19:56. The penumbral eclipse lasted for more than 4 hours and reached 0.82.[17]
2023
The penumbra lunar eclipse on May 5, 2023 will last from 23:12 to 03:34 on May 6. The whole process will take more than four hours, with the maximum eclipse minute of 0.989。[21]However, the penumbra lunar eclipse is invisible to the naked eye, and can only be identified by taking photos[19]The whole process lasted nearly four and a half hours, and was visible nationwide.[20]
2024
On March 25, 2024, the penumbra lunar eclipse appeared.When the penumbra lunar eclipse occurs, the moon looks the same as the full moon. Only the brightness decreases and becomes slightly darker. It is difficult for the naked eye to distinguish the difference, but the change can be seen by photography.The penumbra eclipse occurred during the daytime in China.[23]
Penumbral eclipse table
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The following table lists the time and details of penumbra lunar eclipse in the next 10 years from 2021.[18]
