How does a lunar eclipse occur? What is a lunar eclipse? How is a lunar eclipse different from a solar eclipse
Instruction
As you know, the Moon is the only natural satellite of the Earth. In the earth's sky, it is the brightest object after the Sun. In its movement along the orbit, the Moon, at different periods of time, is either between our planet and the Sun, or on the other side of the Earth. The Earth is constantly illuminated by the Sun and casts a cone-shaped shadow into outer space, the diameter of which at the minimum distance to the Moon is 2.5 times its diameter.
The plane of the Moon's orbit is at an angle of about 5° to the plane of the ecliptic.
If we take into account the precession of the earth's axis and the plane of the lunar orbit, and take into account the perturbations caused by the Sun and other planets of the solar system, it becomes clear that the motion of the Moon in its orbit changes periodically.
At some moments in time, the Sun, Earth and Moon may be on the same or almost on the same straight line, and the earth's shadow will partially or completely cover the Moon. Such an astronomical event is called a lunar eclipse. If the lunar disk is completely submerged in the region of the earth's shadow, a total lunar eclipse occurs. With partial immersion, a partial eclipse is observed. The phase of a total eclipse may not occur at all.
Even with a total eclipse, the lunar disk is visible in the sky. The moon is illuminated by the sun's rays passing tangentially to the earth's surface. The earth's atmosphere is most permeable to the rays of the red-orange spectrum. Therefore, during an eclipse, the lunar disk becomes dark red and not so bright. In 2014 there will be 2 total lunar eclipses - April 15 and October 8. It is clear that an eclipse can only be observed in that part of the globe where the Moon, at the time of its passage through the shadow region, is above the horizon. The maximum duration of a total lunar eclipse is 108 minutes.
During a partial eclipse, the earth's shadow covers only part of the lunar disk. From the Earth, the observer will see a somewhat blurred, due to the scattering of light by the atmosphere, the boundary between the illuminated and shadowed parts of the Moon. Shaded areas take on a reddish tint.
As you know, light rays are able to bend around obstacles. This phenomenon is called diffraction. Thus, around the cone of full shadow in space there is a partially illuminated area - penumbra. Direct sunlight does not penetrate there. If the Moon passes through this area, a penumbral eclipse is observed. The brightness of its glow decreases slightly. As a rule, the eclipse is even impossible to notice without special instruments. For astronomers penumbral eclipses are of no interest.
On January 31st, there will be a supermoon, a total lunar eclipse, and a blue moon, the second full moon in a month. The last time such a combination was observed in 1982, it will repeat only in 2037.
Residents of almost all of Russia will be able to watch the course of the eclipse. Also, the eclipse will be visible in Ukraine, Belarus, Moldova, the Baltic States. In addition, residents of the western part of North America, Canada, Asian countries, Hawaiian Islands, Alaska can follow him. But the inhabitants South America and Africa will find themselves without this spectacle.
On January 31 at 13:49 Moscow time, the Moon will touch the Earth's penumbra - at this time, a penumbral eclipse will begin. It is poorly visible to the naked eye, but as the moon approaches the edge of the earth's shadow, it will become more and more noticeable. At 14:48, the Moon will begin to sink into the shadow of the Earth. It will fully submerge by 15:51. The maximum phase of the eclipse will come at 16:29, when the Moon is near the center of the Earth's shadow. In total, the Moon will spend more than an hour in the earth's shadow.
The exit from the earth's shadow will begin at 17:08. At this time, the Moon will rise above the horizon and acquire a reddish-brown, "bloody" hue. The moon will finally come out of the shadow in two hours - at 19:09.
“I call it the Lunar Super Bowl,” NASA researcher Noah Petro jokes.
To observe the rare phenomenon, astronomers use telescopes located in the Hawaiian Islands.
The moon is one of the most amazing objects in the solar system. Studying the surface of the moon, its geology is the key to understanding our solar system,” says Petro.
NASA is going to broadcast eclipses using telescopes in California and Arizona. It will start at 5:30 EST (13:30 Moscow time).
Simultaneous combination of three NASA astronomical events disable the instrumentation of the Lunar Reconnaissance Orbiter (LRO), an artificial satellite of the Moon. The probe uses solar panels to operate. When the moon is in the shadow of the earth, and the sunlight does not reach the satellite, it has to switch to battery power.
“We fired up the engine to put the satellite in the best possible position - we need to keep it in the light for as long as we can. In other words, we minimized the time he spends in the shade,” explains Petro. He notes that turning off the equipment is just an additional measure that will make it possible to secure the probe. During previous eclipses, however, the equipment continued to operate and collect data. In addition, before entering the shade, the devices will be additionally heated to reduce the load on them.
Watch out, motorcyclist!
During a supermoon, the apparent diameter of the moon increases by 14 percent (compared to the minimum), and the disk can become brighter by 30%.
Despite the increased media attention to the supermoon, astronomers do not see anything in it that deserves special attention, because the difference in the size of the visible disk of the moon cannot be fixed by eye - this can only be done with the help of instruments. Unless this is another reason to make people look at the sky and remember astronomy.
“Supermoons are a great opportunity for people to start observing the Moon, not only on such days, but every time the opportunity presents itself,” Petro noted earlier.
But the American astrophysicist Neil deGrasse Tyson is critical of the hype about supermoons - in his opinion, it discredits the prefix "super".
“If last month's full moon was a 16-inch pizza, this month's supermoon is a 16.1-inch pizza. I'm just reminding,
he tweeted about one of the previous supermoons.
Nevertheless, there are reasons to pay close attention to the supermoon. A recent study published by American scientists revealed an unusual pattern associated with full moons - at this time for motorcyclists, the chances of dying are significantly increased.
Scientists analyzed fatal road accidents in the US, UK, Canada and Australia. They looked at more than 13,000 accidents that occurred over 1,482 days at night, from 4:00 pm to 8:00 am, from 1975-2014 in the United States. Accidents during daylight hours were not taken into account.
494 of the nights considered fell on a full moon. According to researchers' calculations, 4494 accidents occurred on these nights, the rest - before or after the full moon. Nights when the moon did not appear at all were not taken into account. A total of 8,535 accidents occurred in the 988 remaining nights.
In other words, there were 9.1 fatal crashes on every night with a full moon, and 8.64 on any other night. Compared to other nights, there was one additional accident for every two nights with a full moon.
Analysis of accidents in other countries showed similar results.
Moreover, the risk further increased during a supermoon, the moon's closest approach to the Earth, when the moon is on average 30% brighter than during a normal full moon. During the 65 supermoons included in the sample, 703 motorcyclists died, i.e., an average of 10.82 per night. In other words, for every supermoon night, there were two additional deaths.
Epileptics can sleep peacefully
A lunar eclipse also often attracts the attention of publications that are far from science - they publish information about how an eclipse can affect a person's behavior, his physical and mental health. Most of these judgments are scientific research. The position of the Moon in the sky does not affect the exacerbation of mental illness, the number of seizures in epileptics and the number of injuries.
Researchers at the University of Washington have studied more than a hundred examples of lunar impact, but have not found reliable evidence that any phenomena associated with the moon significantly affect the health and behavior of people.
However, psychologists advise suspicious people to be more careful: belief in the influence of the Moon on their condition and the experiences associated with it can really lead to any physical effects - weakness, apathy, drops in blood pressure, panic attacks.
“People who are suggestible, suspicious, suffering from borderline conditions, mental illness, increased anxiety, weakened as a result of treatment or illness should be especially attentive to themselves. On this day, it’s better for them not to make serious decisions, not to overstrain intellectually, not to plan important events, a one-day diet or a decrease in the amount of food they eat is desirable, ”consultant psychologist Arina Lipkina told Gazeta.Ru.
Is this a bad omen?
Lunar eclipses instilled real panic fear in ancient people. Entire generations of people considered lunar eclipses to be a bad omen, until a person mastered science and not some regularities of cosmic and universal scales. It was believed that the burgundy color of the moon is the approach of war, blood, death. Fortunately, science was able to remove the veil of mystery from this phenomenon, and all supernatural ideas about lunar eclipses have sunk into oblivion.
When do lunar eclipses occur?
They arise at a certain time, but only when the full moon comes. At this time, the night luminary begins to pass away from the Earth, opposite to the Sun. Here the Moon can fall into the shadow that the Earth casts at this time. That's when people can watch.
How do lunar eclipses happen?
They happen differently than the sun. The fact is that the Moon does not disappear completely, as the Sun does during a solar eclipse. The moon is only faintly visible. This happens for the following reason: part of the sun's rays, passing through the earth's atmosphere, is refracted in it and already enters the earth's shadow, falling directly on the moon. It is known that the air transmits red rays of light, which is why the night star becomes brown or copper-red.
It is known that the diameter of the Earth is exactly 4 times the diameter of the Moon. Accordingly, the shadow from the Earth is 2.5 times larger than the Moon. All this leads to the fact that the night luminary can sometimes completely enter the earth's shadow, which already causes a total lunar eclipse. Scientists have calculated and concluded that total lunar eclipses are longer than total solar eclipses, and can last up to 1 hour and 40 minutes!
According to the observations of astronomers, up to three lunar ones can occur in one year. It is worth noting that they repeat exactly after the same period of time as solar eclipses, which is 18 years 11 days and 8 hours. Scientists have even given a name to this period: saros (repetition). It is curious that saros was calculated in antiquity, so it is not difficult to calculate and predict the exact day. But predicting the exact time of its onset, as well as the conditions for its visibility, is a more difficult task: different generations of astronomers have been studying the movement of the Moon and the Earth for centuries in order to solve this problem. Currently, possible errors in the calculation of the moments of the onset of lunar eclipses do not exceed 4 seconds!
A lunar eclipse is observed when the Earth's satellite enters the shadow that our planet casts from the Sun, that is, the Earth in this case is between the luminary and the Moon. In this case, the Moon can only partially fall into the shadow, and can be completely covered by it, therefore, partial and total eclipses are distinguished. Every year you can observe two or more lunar eclipses with different phases.
Instruction
When the Sun shines on the Earth, a cone of dense shadow forms on the other side of the planet, surrounded by penumbra. If the Moon at this moment partially or completely enters this cone, a lunar eclipse will be observed from the surface of the planet from the side where our satellite is visible. It does not look as impressive as the sun, but it is easier to observe it. The brightly lit Moon slowly begins to be covered, but remains visible due to the sun's rays scattered in the Earth's atmosphere, which illuminate its surface with a reddish light. The eclipse can last longer, the Moon gradually comes out of the shadow and is again illuminated by the Sun. If the eclipse is partial, then only part of the satellite becomes dark. In some cases, the Moon does not enter the full shadow, but remains in the penumbra - the eclipse is called penumbral.
On average, 2-3 lunar eclipses occur every year, but in some years this phenomenon is not observed at all, and in other years 4 or even 5 lunar eclipses can be seen. The number of eclipses varies from year to year with a certain frequency, which repeats every 18 years and 11 days. This period is called the saros or draconian period. During this period, there are 29 lunar eclipses - 12 less than solar ones. Two thirds of all eclipses are partial and one third are total.
The moon does not have its own light, but its surface reflects the sun's rays, so it serves as a night star for us. During eclipses, our satellite turns red, which is why lunar eclipses are sometimes called the "blood moon".
Why do lunar eclipses happen
These celestial phenomena occur when the Sun, Earth, and Moon line up in a straight line. The sun is behind the Earth, as a result, the Earth casts a shadow on the Moon, and a lunar eclipse occurs.
They always occur on a full moon, but we can't see a lunar eclipse on every full moon. The fact is that the lunar orbit is inclined at an angle of 5 degrees to the orbital plane of the Earth, also known as the ecliptic (the path of the Earth around the Sun). The intersection points of the two orbits are called the lunar nodes, and eclipses can only occur when the full moon occurs near the lunar node. In other cases, the Earth cannot cast a shadow on the Moon's surface.
Thus, for a lunar eclipse to occur, two conditions must be met:
Full moon in heaven;
The proximity of the Earth to one of the lunar nodes.
Types of lunar eclipses
There are 3 types: full, partial and penumbra.
A total lunar eclipse occurs when the central (dark) part of the Earth's shadow covers the entire visible side of the Moon. The Earth's shadow is about 1.4 million kilometers wide.
A partial lunar eclipse can be observed when only part of the visible surface of the moon is covered by the earth's shadow.
When the Sun, Earth and Moon are not aligned perfectly, only the outer part of the Earth's shadow (penumbra) overshadows the Moon. Such an eclipse is called a penumbral.
Why does the moon turn red
Even if the Earth completely blocks sunlight from reaching the surface of the Moon, our satellite is still visible in the heavens. This is due to the fact that the Earth's atmosphere refracts sunlight and indirectly illuminates the lunar surface. During a total lunar eclipse, the moon darkens and turns red, because the earth's atmosphere is most permeable to the rays of the red color spectrum. However, the Moon can also turn yellow, orange, or brown, because clouds and dust particles are present in the earth's atmosphere, and it is they that allow waves of various lengths to reach the surface of our satellite.
Where can you see lunar eclipses
This celestial phenomenon can be seen by everyone who is on the night side of the Earth. It can be observed with the naked eye. The chance of seeing a lunar eclipse is much higher than a solar eclipse (it is visible only in a narrow band in certain areas of the Earth), although both occur at similar intervals. In one calendar year there may be two lunar eclipses (with an interval of about six months), sometimes three, but in some years none occur.
Myths and beliefs about eclipses
The ancient Incas believed that lunar eclipses were caused by a jaguar attempting to devour the moon. The attack of a big cat was explained by the red or blood-red color in which the earth's satellite is painted during a total lunar eclipse. The Incas were afraid that after attacking the moon, a huge jaguar would crash to Earth and start eating people. They tried to drive him away with noise and shouting, teasing the dogs so that they barked loudly.
However, jaguars were not the only predators in mythology who wanted to eat the heavenly body. The inhabitants of ancient Mesopotamia also saw eclipses as an attempt on the moon, but in their history, seven demons were the attackers. Other peoples had similar beliefs, they featured bloodthirsty dragons and other mythical creatures.
The Hupa American Indians of Northern California believed that Luna had 20 wives and many animals, most of them mountain lions and snakes. If they were not brought enough food, they attacked and inflicted wounds, then the blood made the moon red. The eclipse ended when the wives came to the defense, drove off the predators and healed the moon.
The Indians of Southern California believed that the eclipse signaled the illness of the moon, so they sang hymns and prayed for her to return to health.
Not all ancient cultures attributed a negative meaning to lunar eclipses. According to a myth from Benin, the Sun and Moon fight each other, and people come to the rescue to judge them. The ancient inhabitants of Benin believed that during the days of lunar eclipses, one should gather together, resolve old feuds and restore good relations.
I have seen an amazing lunar eclipse more than once. How it happens can be observed without special equipment, but, of course, it is better to use a telescope or a camera lens. Since the lunar eclipse is quite long, about 1.5 hours, even a beginner can prepare for this event and take great pictures. I think this is a great excuse to go out of town, into nature and enjoy the astronomical miracle.
Diagram of a lunar eclipse
It occurs under the following necessary conditions:
- full moon;
- the proximity of the Moon to the node of its orbit;
- the entry of the moon into the cone of the earth's shadow (if the shadow covers it completely, there will be a total lunar eclipse).
You can see a darkened celestial satellite anywhere on our planet in the same way, unlike solar eclipses, which are not visible everywhere.
Periodicity of lunar eclipses
In total, it was calculated that a maximum of 3 lunar eclipses occur per year, and a minimum - none. In exactly the same order, the event will occur no earlier than in 18 years.
Surprisingly, scientists can accurately calculate and determine when and where the next total eclipse will occur. heavenly body. This cyclicality greatly helped researchers to find out the dates of historical events from records of lunar eclipses in ancient chronicles.
I smiled when, reading about Christopher Columbus, I learned such an interesting real fact. He was a literate and quick-witted man, and, knowing when the complete blackout of the Earth’s satellite would come, he frightened the leader of the Indians that he would take the Moon from them if he did not give water and food to his expedition. Horror gripped the Indians when they saw the foreigner's threat coming true, and began to beg him to "return" the night luminary, giving him what he asked for. Columbus was a good fellow and returned the “stolen” Moon to the sky.
It became interesting to me: “But if astronauts or, as is possible in our time, just space tourists find themselves on the Moon at this time, what will they see?” It turned out that the lunar guest at the time of its total eclipse can observe a total eclipse of the Sun!