Why when observing the moon. Moon walk in the daytime across the sky

© Voraorn Ratanakorn | Shutterstock

How did the moon appear?

After the sun shone, the formation of the planets of the solar system began. But it took another hundred million years for the moon to form. There are three theories about how our satellite could have been born: the giant impact hypothesis, the conformation theory, and the capture theory.

Giant Impact Hypothesis

This is the prevailing theory held by the scientific community. Like other planets, Earth formed from a leftover cloud of dust and gas orbiting the young Sun. The early solar system was a hot place where several bodies formed that never reached the status of full-fledged planets. According to the giant impact hypothesis, one of them crashed into the Earth shortly after the formation of the young planet.

It was a Mars-sized body known as Theia. The object collided with the Earth, ejecting evaporated particles of the young planet's crust into space. Gravity pulled the ejected particles together to form the Moon. This birth explains why the Moon is predominantly composed of lighter elements, making it less dense than the Earth - the material that formed it came from the crust, while the planet's rocky core remained intact. As the material gathered around what was left of Theia's core, it was concentrated near the plane of the Earth's ecliptic - the path that the Sun takes across the sky and where the lunar orbit is today.

Conformation theory

According to this theory, gravity contributed to the simultaneous coalescence of material in the early solar system into the moon and earth. Such a moon should be very similar to the planet, and its location should coincide with the current one. But although the Earth and the Moon are mostly made of the same material, the Moon is much less dense than our planet, which would be unlikely if both bodies began to form their cores from the same heavy elements.

Capture theory

It is possible that Earth's gravity has hooked on the passing body, as it has done with other moons in the solar system, such as the Martian moons Phobos and Deimos. According to the capture theory, a rocky body formed in other parts of the solar system could be put into orbit around the Earth. The capture theory explains the differences in the composition of the Earth and the Moon. However, such moons are often oddly shaped, not spherical like the Moon's, and their paths, unlike those of the moon, do not tend to align with the ecliptic of their mother planet.

While the co-formation theory and the capture theory explain some aspects of the Moon's existence, they leave many questions unanswered. The giant impact hypothesis covers most of them, making it the most popular among scientists.

How big is the moon?

The moon is the brightest object in our night sky. It seems quite large, but only due to the fact that it is the nearest celestial body. The Moon is a little more than a quarter of the size of the Earth (27%), which is much smaller than the ratios of the sizes of other satellites to their planets.

© shutterstock

Our Moon is the fifth largest satellite in the solar system. The average radius of the Moon is 1737.5 km, diameter - 3.475 km, less than a third of the Earth's. The equatorial circle is 10,917 km. The surface area is about 38 million square kilometers, which is inferior to the total area of ​​the Asian continent, equal to 44.5 million square kilometers.

“If we imagine that the Earth is the size of a coin, then the Moon in this case can be compared to a coffee bean”, say the researchers.

Mass, density and gravity

The mass of the Moon is 7.35 × 10^22 kg, about 1.2% of the mass of the Earth. In other words, the Earth weighs 81 times more than the Moon. The density of the Moon is 3.34 g/cm3. This is about 60% of the Earth's density. The Moon is the second densest satellite in the solar system after Jupiter's Io, whose analogous parameter is 3.53 g/cm3.

The lunar force of gravity is only 16.6% of the earth. A person weighing 45 kg on Earth would weigh only 7.5 kg on the Moon. A person who can jump 3m on Earth will be able to jump almost 18m on the Moon.

As with most worlds in the solar system, the moon's gravity varies with the characteristics of its surface. In 2012, NASA's GRAIL mission mapped lunar gravity in unprecedented detail. "When we see a noticeable change in the gravitational field, we can synchronize that change with surface topographical features such as craters or mountains," mission officer Maria Zuber of the Massachusetts Institute of Technology said in a statement.

Although the Moon is the closest and one of the most studied astronomical objects, the interest of scientists in it does not wane. "The Moon is the Rosetta Stone through which we understand the rest of the solar system," said Noah Piotr, NASA LRO Project Associate.

Supermoon

Since the Moon's orbit is not perfectly round, it is either closer to us or further away. Perigee is the point in the lunar orbit at which it is closest to Earth. When the full moon coincides with perigee, we get a supermoon that is 14% larger and 30% brighter than usual.

The main reason why the moon's orbit is not a perfect circle is because the moon has a lot of tidal, or gravitational forces. The gravity of the Earth, the Sun, and the planets in our solar system affects the Moon's orbit, causing it to make these close passages.

A supermoon occurs approximately every 414 days. But keep in mind that this is an average. For example, 2016 boasted three supermoons.

Pictures of the giant Supermoon in 2016 became a hit on social media.

Residents of Russia, Europe, North and Latin America shared their amateur pictures of the astronomical phenomenon, which became the largest over the past 68 years.

New York. © Stan Honda | spaceweather.com

What happened, why does the moon take up more space in the sky than usual? The fact is that the distance between the centers of the Earth and its natural satellite has decreased by 50 thousand kilometers relative to the apogee. Therefore, the Moon appears 14% larger in the earth's sky and 30% brighter. This is the largest and brightest full moon in almost 70 years!

The difference between the moon at perigee and apogee. © Sky and Telescope, Laurent Laveder

Supermoons happen quite often. In 2016, it was observed on October 16, November 14 and December 14. But none of them will surpass the November event in terms of entertainment!

Loi Krathon is a festival in Thailand that takes place during the November full moon. © Jeff Dai | spaceweather.com

The #supermoon hashtag is trending on Twitter. Pictures of the huge moon spread to other social networks.

Here is a photo posted on Twitter by Luca Parmitano, an Italian cosmonaut who is now in Kazakhstan to support colleagues - Frenchman Tom Pesce, American Peggy Whitson and Russian Oleg Novitsky - who went to the ISS on November 17, 2016.

The photographs below show the Soyuz-FG launch vehicle carrying the Soyuz MS-03 spacecraft against the backdrop of the Supermoon.

The next time the Moon will come to such a close distance is November 25, 2034. There is only one supermoon in 2017, December 3rd. In 2018, two - on January 2 and 31.

« blue moon called the second full moon in a month. The first happened on January 2, 2018.

January 31, 2018 year, the inhabitants of the Earth witnessed a unique astronomical event: on this day The supermoon coincided with the "bloody" lunar eclipse and the so-called "Blue Moon". The last time this was observed a century and a half ago, in 1866.

During a Supermoon, the Full Moon appears larger and brighter than usual as it approaches the Earth. In this case, the distance between the satellite and our planet was 350 thousand kilometers.

The "Blood Moon" is the result of the refraction of the sun's rays during a total lunar eclipse, when the satellite is entirely in the earth's shadow.

horizon illusion

A little-understood optical effect can visually magnify the Moon as it rises behind distant objects on the horizon. This effect, known as the moon illusion or Ponzo illusion, has been observed since ancient times, but still has no generally accepted explanation.

According to one theory, we are accustomed to seeing clouds only a few kilometers above us, while we know that clouds on the horizon can be tens of kilometers away. If a cloud on the horizon is the same size as overhead clouds usually are, despite the distance, we know it must be huge. And since the Moon near the horizon is the same size as we see it above our head, our brain automatically enlarges it.

Another hypothesis suggests that the Moon appears larger near the horizon because we can compare its size to nearby trees and other objects on Earth - and it takes on horrendous proportions in comparison. Overhead, against the background of vast outer space, the Moon seems small.

One way to check the illusory nature of the picture is to put your thumb up to the visible moon and compare its size with a fingernail. When the moon rises higher, look at it again and you will see that the moon will be the same size compared to your fingernail.

Why does the moon appear larger on the horizon?

When the moon is full, an optical illusion is created that has baffled observers since the time of Aristotle. Rising moons, especially full moons, look strangely huge near the horizon and seem smaller and smaller as they rise in the night sky.

© lOvE lOvE | shutterstock.com

The moon illusion exists solely in your head. The moon does not change size, and while its distance from the Earth changes slightly over time, it does so slowly for significant transformation to occur overnight.

If you want proof that the moon illusion is a completely psychological phenomenon, just measure the moon at the horizon and high in the sky with a ruler. The "lower" Moon will appear much larger, but the ruler will show that its diameter has not changed.

The cameras also help bring the moon to clean water. Take several consecutive photographs of the Moon from the same point, and then combine them - it will be obvious that the size of the satellite has not changed.

© Jingpeng Liu | spaceweather.com

© Ken Sperber | spaceweather.com

So what's going on? When we look at the Moon, rays of reflected sunlight form an image on the retina of the eye with a diameter of 0.15 mm.

"High and low moons create a spot of the same size, says NASA scientist Tony Philips. - Yet the brain insists that one is greater than the other.”.

Illusion Ponzo

One of the explanations for the "self-deception" of the brain can serve. In the animated image below, the top yellow bar appears wider than the bottom because it is "much farther" (i.e. closer to the horizon) on the train tracks. Our brain adds width to compensate for the expected distortion. As with the high and low moons, both bars are the same length, as the vertical red lines clearly show.

Another illusion that may explain the changing size of the moon is the Ebbinghaus illusion. It lies in the difficulty of the brain's perception of the relative sizes of objects. In the image below, the orange circles are the same size, although the right one appears larger. Near the horizon, the Moon is surrounded by relatively small buildings and trees, so it can appear larger than in the sky, where there are no objects for comparison.

Ebbinghaus illusion

Unfortunately, all explanations of the illusion offered at the moment have flaws (for example, the Ebbinghaus illusion does not work in the case of sailors and pilots - there are no buildings and trees in the sky and sea - but people see the illusion) - scientists are still heatedly debating on this occasion.

An animated overview of attempts to understand the lunar illusion - in the video of science popularizer Andrew Vanden Heuvel (Russian subtitles available):

Does the moon rotate?

Those who observe the Moon from the Earth may notice that the satellite, passing along its orbit, always turns to its planet with the same side. A logical question arises, does the Moon rotate or is it stationary relative to its axis? Despite the fact that our eyes say no, scientists say the opposite is true - the moon does rotate.

© taffpixture | shutterstock

The period of revolution of the Moon around the Earth is 27.322 days. Approximately 27 days are required for the satellite to make one revolution around its own axis. That is why for observers from the Earth, the illusion is created that the Moon remains absolutely motionless. Scientists call this situation synchronous rotation.

However, it is worth paying attention to the fact that the Moon's orbit does not completely coincide with its axis of rotation. The Moon travels around the Earth in an elliptical orbit, a slightly elongated circle. When the Moon approaches the Earth at its maximum possible distance, it rotates more slowly, which allows you to see the usually hidden from observers 8 degrees on the east side of the satellite. When the Moon moves away to its maximum distance, the rotation is faster, so an additional 8 degrees can be seen on the western side.

It should be noted that the far side of the Moon is visually very different from what we are used to seeing from the Earth. If the near side of the moon is mainly composed of lunar seas - large dark plains created by hardened lava flows - and low lunar hills, then the reverse side of the satellite is literally dotted with craters.

Meanwhile, scientists say that the period of rotation of the moon was not always equal to its period of revolution. Just as the Moon's gravity affects ocean tides on Earth, Earth's gravity also affects the Moon. But since there is no ocean on the planet's natural satellite, the Earth acts directly on the surface of the Moon, creating tidal bulges on it along the line pointing to the Earth. Tidal friction gradually slows the moon's rotation.

The satellite itself has the same effect on Earth, so every 100 years the length of the day increases by a few milliseconds. So, during the time of the dinosaurs, the Earth made one revolution around its axis in 23 hours. The 24 hours (or 86,400 standard seconds) now taken per day for a revolution around its axis at the Earth took in 1820. Since then, the solar day on the planet has increased by about 2.5 milliseconds.

Is the moon warm or cold?

Temperatures on the Moon are extreme, ranging from simmering heat to freezing cold, depending on where the Sun shines. The Moon does not have a significant atmosphere, so it cannot retain heat or insulate the surface.

© Ricardo Reitmeyer | shutterstock

The moon makes a complete rotation on its axis in about 27 days. A day on one side of the moon lasts about 13.5 days, and the next 13.5 days it is plunged into darkness. When sunlight hits the moon's surface, temperatures can reach 127°C. After sunset, it can drop to minus 173 °C. The temperature changes across the entire surface of the Moon as it rotates both around the Earth and around its own axis.

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The lunar axis is tilted by about 1.54 degrees - much less than the earth's axis (23.44 degrees). This means that there are no seasons on the Moon like there are on Earth. However, due to the tilt, there are places at the lunar poles that never see daylight.

The Diviner instrument on NASA's LRO probe determined that the temperature in the lunar south pole craters is minus 238°C and minus 247°C in the north pole crater. "These temperatures are, to the best of our knowledge, the lowest measured anywhere in the solar system, including the surface of Pluto.", said David Page, Principal Investigator of the Diviner Instrument and Professor of Planetary Science at the University of Los Angeles. Since then, NASA's New Horizons spacecraft has established a temperature range on Pluto that is comparable between minus 240 and minus 217°C.

Scientists suspected that water ice could exist in the dark craters of the Moon, which are in constant shadow. In 2010, NASA radar aboard India's Chandrayaan 1 spacecraft detected water ice in more than 40 small craters at the north pole. According to preliminary estimates, its volume is more than 1.3 trillion pounds.

What color is the moon?

According to NASA - the Moon is gray, according to Soviet scientists - brown. On December 15, 2013, the Chinese space mission Chang'e-3 transmitted images from the moon: The moon is brown! Here, NASA supporters (Vitaly Yegorov, aka Zelenyikot) caught on and came up with an explanation: “the white balance was not corny on the cameras.” This video proves that NASA supporters are wrong.

Why does the moon turn red?

« blood moon» appears when the earth's satellite passes the eclipse phase. Although the phenomenon is not of particular astronomical significance, the view in the sky is striking - the usually white Moon turns red or brick brown.

The moon revolves around the earth and the earth revolves around the sun. The moon takes about 27 days to orbit the earth, and it also goes through regular phases in a 29.5-day cycle. The difference between these two cycles is due to the position of the Sun, Earth and Moon relative to each other, which is constantly changing.

Lunar eclipses can only occur on full moons, when the Sun is fully illuminating the surface. Usually the full Moon does not create eclipses, as it rotates in a slightly different plane than the Earth and the Sun. However, when the planes align, the Earth passes between the Moon and the Sun and blocks the sunlight, creating an eclipse.

If the Earth partially covers the Sun, and the darkest part of its shadow falls on the surface of the Moon, the phenomenon is called a partial eclipse. You will see a shadow that "bites off" part of the satellite. Sometimes the Moon passes through the lighter part of the Earth's shadow, causing a penumbral eclipse. Only experienced skywatchers can tell the difference, as the Moon darkens just a tiny bit.

© AZSTARMAN | shutterstock

Ancient cultures often didn't understand why the moon turns red. At least one explorer - Christopher Columbus - used this to his own advantage in 1504. Columbus and his crew are stranded in Jamaica. At first, the locals were hospitable, but the sailors robbed and killed the natives. It is clear that the Jamaicans had no desire to help them in their search for food, and Columbus realized that famine was approaching. Columbus had an almanac with him, which indicated that the next lunar eclipse would soon occur. He told the Jamaicans that the Christian god was upset because Columbus and his crew had no food and would paint the moon red as a symbol of his wrath. When the event actually happened, the frightened Jamaicans "with loud cries and weeping ran from everywhere to the ships, loaded with provisions, begging the admiral to intercede for them before God."

During a total eclipse, however, something spectacular happens. The moon is completely in the earth's shadow, but sunlight scattered in the earth's atmosphere still reaches the surface of the moon. Since the rays of the red spectrum are the most scattered, the Moon looks bloody.

How red the Moon becomes depends on pollution, cloud cover, or debris in the atmosphere. For example, if an eclipse occurs shortly after a volcanic eruption, particles in the atmosphere can make the moon appear darker than usual.

A partial lunar eclipse has occurred August 7, 2017.
January 31, 2018: full eclipse. Lunar metamorphoses could be seen on four continents of the planet - in Asia, Australia, the Pacific Ocean, in the west of North America. In the central part of Russia, it is only partially visible.

The most fortunate were the inhabitants of Siberia, the Far East, Japan, Australia and the US West Coast - in these regions the phenomenon was especially spectacular.

In Moscow, cloudy weather prevented observations, moreover, the eclipse over the capital was not complete. In St. Petersburg, the red-orange Moon was clearly visible.

July 27, 2018: full eclipse. Seen in South America, Europe, Africa, Asia, Australia.
January 19, 2019: full eclipse. It is seen in North and South America, Europe and Africa.
July 16, 2019: partial eclipse. Seen in South America, Europe, Asia, Australia.

While there are planets and moons throughout the solar system, only the Earth experiences lunar eclipses because its shadow is large enough to completely obscure the moon.

The moon is gradually moving away from our planet (about 4 cm per year), and the number of eclipses will change. There are an average of 2-4 lunar eclipses each year, and each one is visible from about half of the Earth.

Layers of insulation

Astronauts on the Moon were protected from extreme temperatures by their space suits. The suits had multiple layers of insulating material overlaid with a highly reflective outer layer. In addition, they had built-in heaters and cooling systems.

core temperature

The moon has an iron-rich core with a radius of about 330 km. The core temperature is thought to be between 1.327 and 1427°C. The core heats the inner layer of molten mantle, but it is not hot enough to warm the surface. Because the Moon is smaller than the Earth, the Moon's internal temperatures don't rise as high.

"The temperature in the interior of the Moon is probably cooler than that of the Earth because the Moon is smaller - hence its internal pressure is also less," NASA planetary scientist Rene Webber explained.

another side of the moon

The Deep Space Climate Observatory has aimed its cameras at Earth, capturing a plethora of images since July 6, 2015, when the Moon came in front of our planet.

The visible difference in texture and lighting between the Moon and the Earth in the animated image is not a graphical rendering. The effect is created naturally, thanks to the Earth's atmosphere.

The moon is enveloped only by a thin haze of argon. Sunlight touches the surface of the satellite and is reflected in the opposite direction. Light passing through the Earth's atmosphere, on the other hand, is scattered by dense air. Therefore, the illumination of our planet is softer.

The EPIC camera has tracked the far side of the moon for the second time in its operation, and for the third time recorded the satellite crossing its field of view.

We do not see the far side of the Moon from Earth, as the satellite rotates synchronously with respect to our planet. This means that the rotation of the moon - the length of its day from dawn to dawn for anyone standing on its surface - takes the same time as the revolution of the satellite around the Earth.

Why is the moon always different?

The moon is the first celestial object that attracts the attention of man. Everyone knows about the phases of the moon changing throughout the month - but what exactly causes these changes?

Moon phases. © Orion 8

The moon itself shines by reflecting sunlight. Relative to our planet, with the exception of the Sun, of all celestial objects, the Moon has the largest angular size - the full Moon is 30 times larger and more than 1300 times brighter than Venus.

Interestingly, the phases of the moon can be seen right at home - after a little experiment. All you need is a tennis ball, which has a rough texture. You need to go outside and hold the ball, focusing on the Sun. If the Moon is also visible in the sky, then you should hold the ball at arm's length towards it. If the angular distance between the ball, which acts as the Moon, and the Sun is the same as between the real Moon and the Sun, then both the Moon and the ball will be in the same phase. Of course, if you move the ball to a different position, its phase will change due to the change in the angle of the glow. You can move the ball in such a way that it is completely lit (full moon), or only half lit (quarter).

© NASA

Lunar phases are related to the position of the Moon in the Earth's orbit. The satellite goes through the entire cycle of phases in 29.53 days - from one new moon phase (when the Moon is not visible) to another. In this phase, from the point of view of an observer on Earth, the Moon is in the same position in the sky as the Sun. Therefore, we cannot see the "new" Moon unless it passes directly in front of the Sun - then a solar eclipse occurs. We see half of the moon (phase of the first quarter) when it passes the first quarter of the cycle - approximately 7.4 days after the new moon. At this stage, it rises 6 hours later than the Sun, usually around noon.

The full moon phase occurs 14.8 days after the new moon, the moon is directly opposite the sun, its disk is completely illuminated. It rises at sunset, its highest point in the sky is at midnight, and sets at dawn.

The last quarter (when the other half of the moon is illuminated) occurs 22.1 days after the new moon. In this phase, the Moon rises 6 hours before the Sun - around midnight.

Map of the mineral composition of the earth's satellite

We are used to seeing the Moon in discreet shades of gray. But in this mosaic, small differences in color have been exaggerated to create a multicolored lunar landscape. The high-resolution images included in the mosaic were taken during the full phase of the moon.

© Alain Paillou

The colors correspond to real differences in the mineral composition of the lunar surface. Blue hues show areas rich in titanium, orange and purple - regions with relatively low content of titanium and iron.

The bewitching Sea of ​​Vapors with a wide arch of the lunar Apennines above it - just below the center. Top left - the dark bottom of the Archimedes crater with a diameter of 83 km. The site above the arch of the Apennines is the landing site of the Apollo 15 mission.

Analysis of rock samples obtained during the Apollo missions became the basis for creating multi-color images used to study the composition of the Moon's surface.

Moon in 100 megapixel image

© Sean Doran | Flickr

NASA Master Image Processor Sean Doran combined images taken by the Lunar Reconnaissance Orbiter to create something incredible - a 100-megapixel image of the Moon that he posted on his "space" Flickr page.

One LRO WAC image has a resolution of 100 meters per pixel and covers about 60 km of the lunar surface. The pictures were taken from a vertical angle, so in order to get the shape of a lunar ball, Doran had to plot them on a sphere using altimeter data. As a result, he got an image, zooming in on which, you can observe all the richness of the detail of the lunar relief.

To see all the details, . Its total size is 15 MB.

© Sean Doran | Flickr

Video: © Sean Doran | Made with Lunar Reconnaissance Orbiter Camera data

Earth and Moon circling in dance: a rare joint video

Only on rare occasions have the Earth and Moon been photographed together. One of the most impressive joint photo shoots took place 25 years ago, in December 1992. Then the Galileo spacecraft, orbiting Jupiter, used optical zoom and observed our inseparable pair from a distance equal to about fifteen distances between our world and its only satellite.

The processed video combines 52 historical images with improved color characteristics. While the Moon may appear small next to the Earth, no other planet in the solar system has a moon of such comparable size. The sun, far to the right, illuminated each sphere only halfway, so one part of the Earth is in shadow, and the usual white clouds, blue oceans and continents are visible on the other.

In the sky of an observer located in the center of the side of the Moon facing the Earth, the Earth does not stand still at the zenith, but describes a small ellipse during the month (the major axis is 15 degrees, the minor axis is 13).

The farther the observer is from the center of the lunar disk visible from the Earth, the lower in relation to its horizon is the ellipse along which the visible movement of the Earth occurs. The distance from the center of the disk to the point of observation, at which this ellipse touches the horizon of the lunar observer, is borderline: at a shorter distance, the Earth is always visible in the sky, and at a greater distance, in a certain band on the surface of the Moon, one can observe the sunrises and sunsets of the Earth. This band surrounds the entire lunar disk, its width varies from the equator to the poles. Even farther from the center of the visible disk, beyond this band, the Earth from the Moon is never visible at all.

Let's follow how the Earth rises and sets above the horizon of observers located on the Moon's equator at the points where the ellipse touches the horizon. Two more points coincide with the point of contact: the rising and setting of the Earth. There are two such observation points at the equator: near the left (L) and right (R) edges of the visible side of the Moon. They are interesting because in them the Earth rises to the greatest height at sunrise compared to the height of the ascent above any observation points on the Moon. At points L and R, the sunrise lasts two Earth weeks and the sunset two weeks.

At the equator of the Moon, the main role is played by the repeatedly described libration in longitude. Libration in longitude (see Fig. 1) occurs because the Moon's orbit is not a circle, but an ellipse. Therefore, when the Moon is at the point of the orbit A, from the Earth one can see how a section of 15 degrees in longitude (L) is closed behind the left edge of the Moon, and open on the other part of the orbit, at point B. Behind the right edge of the visible side of the Moon (Pr) the same thing happens, but in antiphase. Therefore, from the Earth, it seems that the Moon is swaying. It is possible to notice this from the Earth only with regular observations of the Moon, since the phenomenon proceeds very slowly, and the rotation of the Moon itself is small.

Picture 1

An observer who is in the opening and closing band of the Moon also sees the Earth, it also seems to him that the Earth is swaying - rising and setting.

If libration in longitude were the only libration, then the apparent motion of the Earth on the Moon's side would be in a straight line, for an observer on the Moon's equator up and down. But at the same time there is libration in latitude. Therefore, this straight line is divided into an arc of rising and an arc of setting. The size of the major axis of the ellipse is determined by the libration in longitude, and the minor axis of this ellipse is the result of the libration of the Moon in latitude.

Comparing the rising and setting of the Earth with the onset of day and night on the Moon and with the phases of the Earth allows us to more clearly imagine what a lunar observer could see. It is also necessary to recall that the disk of the Earth in the lunar sky is 14 times larger than the disk of the Moon in our sky, and that during the time that the Earth describes an ellipse in the sky of the Moon, it turns around its own axis 27 times.

At point A of the lunar orbit, an observer located on the Moon at point L sees that the rising of the Earth begins in the second half of the night (a day on the Moon is approximately equal to an Earth month). The earth rises very slowly, while its appearance changes. From behind the horizon, it appears in the form of a slightly diminished half with a bulge upwards. Morning comes. Gradually "losing weight", the Earth turns into an aging blue sickle with long orange legs, resembling an arch. The sickle is getting thinner, and the horns are getting longer. At noon, in a lunar black sky, the Earth appears as a dark disk in a red-orange halo. This is the new earth phase. After noon, the Earth still continues to rise and turns into a young sickle in the form of a boat, and the horns above it almost close. When approaching point B of the lunar orbit, the crescent grows and becomes almost half of the Earth's disk, the Earth reaches its highest position, culmination, rising above the horizon to a height of ... no higher than 16 degrees.

On the moon - evening. Above point L, the same slow setting of the Earth begins. Its illuminated part increases to a full disk (full earth). Night falls on the moon. Mountains, valleys and plains are illuminated by the ghostly bluish-greenish light of the full Earth. It shines more than 60 times brighter than our moon. The earth still continues to set, its illuminated part is decreasing. When the Moon comes to point A of its orbit and becomes a little less than the decreasing half, the Earth will reach the horizon at the observation point L. The sunset is over, the next lunar day is a new sunrise and sunset.

On the right edge of the lunar disk at observation point Pr, the Earth rises in the evening at point B of the lunar orbit, at the same time that the setting begins at point L. At lunar midnight during full earth at point Pr, the Earth continues to rise. Morning comes on the moon. The illuminated part of the Earth is decreasing. When it becomes a little less than the waning half, it will culminate over the Pr point, also at a height of about 16 and degrees above the horizon. This will happen at point A of the lunar orbit. And immediately the two-week setting of the Earth will begin, exactly at the same time when the Earth begins its sunrise over point L. Lunar morning, afternoon and part of the evening the Earth descends over point Pr, touches the horizon at point B of the lunar orbit and begins a new sunrise.

On fig. Figure 2 shows an ellipse of the apparent motion of the Earth at observation points located on the equator of the Moon in the band of the rising and setting of the Earth. It can be seen that with increasing distance from the center of the disk, an increasing part of the ellipse falls under the horizon, while its smaller part remains above the horizon of the observer (L, L1, L2, L3, L4, Pr, Pr1, Pr2, Pr3, Pr4). At the intersection points of the ellipse with the horizon, the Earth rises and sets once a lunar day. At points L4 and Pr4, the ellipse goes completely below the horizon.

Figure 2

From observation point L to point L4 and from point Pr to Pr 4, the Earth's climax above the horizon is lower and lower, sunrises occur later and sets earlier, which means that the time of visibility of the Earth above the horizon of the lunar observer decreases. In this case, the distance between the points of sunrise and sunset with the distance of the observer from the center of the disk first increases from zero at point L to 13 degrees at point L2, and then decreases again to zero at point L4, similarly in the right side of the Moon. Rise and set occur on the same side of the horizon - in the direction of the center of the visible disk of the moon.

On fig. 3 it can be seen that at all latitudes of the Moon, the axes of the ellipse along which the movement of the Earth visible in the sky of the Moon occurs are inclined to the horizon the more, the greater the latitude of the place of observation. The ellipse "lies" at the poles. At mid-latitudes, it touches the horizon or intersects with it in an oblique position, so the arcs of sunrise and sunset are not symmetrical. In any direction, with distance from the center of the disk, an ever smaller arc of the ellipse remains above the horizon, and the visibility time of the Earth decreases. At all lunar latitudes, the picture of the rising and setting of the Earth unfolds in the direction of the horizon, directed towards the center of the visible side of the Moon.

Figure 3

With distance from the equator, the position of the earth's crescents (and other phases) with respect to the observer's horizon changes from horizontal to vertical. After all, the convex side of the illuminated part of the Earth is always facing the Sun, and the Sun rises almost vertically above the equator with a daily movement, and near the poles of the Moon it rolls along the horizon. (The above photograph of the Earth was taken not from the surface of the Moon, but from the orbit of a spacecraft).

The description of all the phenomena considered will become much more complicated if we take into account that the librations of the Moon are the total result of the action of many phenomena occurring with different periods.

Moving in orbit, the Moon really sways, because under the influence of the tides from the side of the Earth, it has acquired an ovoid shape. This is physical libration.

The reason for libration in latitude is that the axis of the daily rotation of the Moon is inclined to the plane of the ecliptic. Due to libration in latitude for an earthly observer, 13 degrees of the Moon's surface above the upper and lower edges of its disk open and close.

From the Earth, it can be seen that the Moon simultaneously experiences libration in longitude and latitude. As a result of these two wiggles, the center of the Moon's disk, visible from the Earth, describes a small ellipse. Therefore, to a lunar observer who is in the center of the visible disk and moves along the ellipse with it, it seems that the Earth describes a similar ellipse in his sky.

Less significant librations occur because the motion of the Moon in orbit is very complex, for example, the inclination of the plane of the lunar orbit to the plane of the ecliptic changes, the orbit of the Moon itself around the Earth continuously rotates in its own plane. Many other features of the motion of the Moon are also observed from the Earth. As a result, the parameters of the ellipses, along which the visible movement of the Earth in the sky of the Moon takes place, change continuously from month to month, the ellipses do not close, but pass one into another, forming a complex spiral.

The moon is visible in the sky due to the fact that the sun illuminates it. The phases of the moon depend on the position of the night star relative to the Earth and the Sun. During the full moon, the Sun, the Earth and its satellite are on the same line. At the same time, the Moon occupies the position farthest from the Sun, and when the daytime luminary, the night one, begins to set.

On the contrary, at the new moon, the Moon “rises” and “sets” behind together with the Sun. At the same time, it is not visible to the naked eye, as it is completely covered by the shadow of the Earth.

The Earth's axis is tilted relative to the planet's orbit by 23.5 degrees. When moving around the Sun during the year, the planet turns to the star, then one side, then the other. This, in turn, gives rise to a change of seasons, and during each season the Sun changes its trajectory across the sky.

Since, with the change of seasons, the Sun changes its position and movement in the sky relative to the horizon, the Moon will also appear on the dome of the sky and disappear from it at different times and in different places.

In this case, one should take into account the difference in seasons in the northern and.

How to predict the sunset of the moon

You can predict where the lunar sunset will be observed, guided by the Sun. Every day, the Moon lags behind the Sun by 12 degrees, sliding across the sky also in an easterly direction. This is that the time it lags behind the Sun is 50 minutes per day.

The earth rotates from west to east, clockwise. Therefore, everything that you observe in the sky moves in the opposite direction, from east to west: the stars, the Sun, the Moon and the planets.

If at the new moon the Moon sets beyond the horizon in the same place as the Sun, and also simultaneously with it, then in other phases the place and time of the lunar sunset will differ from the solar one, depending on the degree of the Moon's lagging behind.

On the young, a thin horn of the Moon is visible above the horizon, when the Sun has already set. The first quarter of the Moon coincides with the position of the night star 90 degrees to the left of the Sun. Then, if the Sun has set in the southwest, then the Moon will set below the horizon in the west. This happens in winter, and in the south - in summer.

The location of the moon's setting relative to the horizon also depends on the degree of latitude.

The full moon is 180 degrees to the left of the sun and 12 hours behind it. During the sunset, the moon rises. And if in the northern hemisphere the winter Sun sets in the southwest, then the moon will disappear beyond the horizon in the northwest.
The aging Moon in the last quarter is 270 degrees to the left of the Sun and appears in the sky 18 hours later. Its sunset coincides with noon. In winter and summer in the northern hemisphere, it will occur in the west, in spring in the southwest, and in autumn in the northwest.

→ Moon observation

The Moon is a natural satellite of the Earth with an orbital period of 29.53 mean solar days. It is important to note here that the period of the Moon's revolution coincides with the lunar day (the period of revolution of the Moon around its axis), and therefore the Moon is always turned to the Earth by the same side (the other is always hidden from us).

Before you start observing the Moon with a telescope, you should study the structure of the lunar surface in advance, including large and small details (these can be dark and light formations, continents, oceans, seas, large craters, mountain ranges, cracks, peaks, terraces and ledges , traces of lava eruptions and accumulations of stones). See map.

When directly observing through a telescope, one should take into account the fact that the Moon is a very bright celestial object (the second after the Sun), so it is necessary to use a special neutral lunar filter that would attenuate the light and allow even small details of the surface to be seen.

When observing the Moon through a telescope, one must remember that the main obstacle here is not even city lights or the smoke of factories in winter, but atmospheric turbulence (that is, at the very horizon, the surface of the Moon is very distorted, and therefore really high-quality observations can be obtained only when when they are highest in the sky).

In case of different weather conditions, you should have eyepieces with different focal lengths (for example, in a turbulent atmosphere, it is not recommended to use a high magnification). Plus, you should take care of the place from which the observation is carried out: there should not be lighting there (or it should be weak and red).

The most favorable moment to start observing the Moon is the third and subsequent days after the new moon (this is when the details of the relief begin to be seen). For example, on the third day, the terminator (that is, the dark border of light and shadow) passes through the center of the Sea of ​​​​Crisis. Here, the mountains surrounding the sea, as well as some large craters (Langren, Petavius, Furnerius), will be interesting enough to observe. On the fifth day, when the terminator passes through the Taurus mountain region, such large craters as Atlas, Hercules and Jansen can be observed. In the first quarter of the lunar cycle, one can observe the Sea of ​​Cold, the Sea of ​​Rains, the adjoining Alps and the Apennines, as well as large craters: Ptolemy, Alfons, Arzakhel, Plato, Copernicus and Tycho (light rays that diverge from each of the craters will be curious here. On the tenth In the afternoon, you can see the Rainbow Bay, the Jura Mountains, as well as the large southern mainland, densely covered with craters.By the twelfth day, the craters Kepler, Aristarchus (which is the brightest object due to the rays diverging from it) and Shikkard are in the visible part.During the full moon, the terminator disappears , and the entire visible part of the Moon is clearly visible (the craters Tycho, Copernicus, Kepler, Aristarchus, Langren and Proclus, as well as the rays of the craters Monsieur, Bessel and Ross).

Now let's talk about short-term events that can be observed on the moon. These are, first of all, emissions of gases from craters and outbreaks that appear because of this, as well as outbreaks caused by the fall of meteorites. What can be observed during such phenomena? Firstly, it can be a change in the outlines and contours of objects, a change in the clarity of the image and its brightness, as well as the appearance of light or dark spots and dots. Separately, it is worth highlighting such rather strange phenomena as darkening (that is, a kind of spot that floats on the lunar surface), as well as various lights: bluish (Aristarchus crater), reddish (Aristarchus and Gassendi craters).

What are the possible causes of these phenomena? There are quite a few of them: tides (which can lead to the formation of cracks), albedo changes, thermal shocks, magnetism, ultraviolet radiation, solar wind, tremors deep in the bowels of the Moon, etc.

Most often, such phenomena can be observed in the area of ​​the Aristarchus crater (where they have been recorded more than 100 times), the Plato crater, in the Schroeter valley, and also in the Sea of ​​Crises. The activity of such phenomena also depends on the position of the Moon relative to the Earth. For example, the maximum number of optical phenomena is observed during the passage of the Moon through perigee (approximately three days) and apogee.

A full moon is often thought of as a phenomenon that lasts all night, but this is misleading because the Moon as seen from Earth gets bigger or smaller all the time (though too slowly to notice with the naked eye). The size of the moon reaches its absolute maximum at the moment when the increase stops.

Since a full moon occurs every 29.5 days, February is the only month of the year that may not have a full moon. In each of the remaining months, it is guaranteed to occur at least once.

When the full moon coincides with the Moon's closest approach to Earth in its elliptical orbit, a rare phenomenon known as a "supermoon" occurs. The most recent supermoon occurred on the night of September 27-28 last year, and the next time it can be seen only in 2033.

The full moon is often associated with temporary insomnia. In the past, the reason for this opinion was obvious: people could not sleep properly with a full moon due to the bright light it reflects. However, today, given the bright artificial light that surrounds us in everyday life, this is unlikely to be the cause of the insomnia that many people continue to suffer during this lunar phase.

It is sometimes claimed that surgeons used to refuse to operate during a full moon because the risk of death due to the loss of the patient's blood increased. Studies conducted in Barcelona found a statistically significant relationship between the lunar phase and hospitalization of people with gastrointestinal bleeding.

A full moon is considered unlucky if it falls on a Sunday, and lucky if it occurs on a Monday. In fact, the word "Monday" in English - "Monday" - came from the Old English word "Monand?g" or the Middle English word "Monenday", which means "lunar day".

It is believed that the full moon causes mental disorder and lycanthropy (a form of insanity in which the patient imagines himself to be a wolf). One of the most popular beliefs was that a person can turn into a werewolf if, on one of the summer nights, on Wednesday or Friday, he slept on the street with a full moon that shone right in his face.

The British Air Force used the light reflected from the full moon to launch an attack on the German city of Lubeck on the night of Saturday, March 28, during World War II.

Dogs are known to bark and howl more during the full moon than at other times, but they can also be more aggressive. A study by the Bradford Royal Infirmary found that dogs bite twice as often during a full moon than on other days.

The full moon is the brightest object in the night sky. Its apparent magnitude (a measure of the brightness of a space object from the point of view of an observer from the Earth) is -12.74 (for the Sun - -26.74).

The full moon was supposed to affect people in the same way it affects the oceans through tidal force, since the human body is almost 75% water, but in fact the tidal effect on such a small scale is completely negligible.

When two full moons fall in the same calendar month, the second full moon is called a Blue Moon. A similar phenomenon occurs, on average, once every 3 years.

According to one of the most common superstitions, more children are born on the full moon than at other times. This statement is not supported by any scientific research. However .

When the full moon coincides with a total lunar eclipse, it appears red. During this time, the only light we see is the light that is refracted by the Earth's shadow. It appears red for the same reason that sunsets are red—due to the Rayleigh scattering of the blue light present in greater amounts.

It was believed that the full moon drives people crazy. The word "sleepwalker" was used to describe a person who was considered mentally ill, dangerous, stupid, or unpredictable—conditions attributed only to insanity. This word comes from the Latin word "lunaticus", one of the meanings of which is "possessed, possessed".

Some wild animals behave differently during a full moon. For example, lions usually hunt at night, but the day after the full moon, they go hunting during the day, as scientists suggest, to compensate for hunger, which reached its maximum at the full moon.

The full moon is often associated with an increase in strange and inexplicable things, but this opinion may be misleading. People have this feeling because during the full moon they pay more attention to unusual events. In fact, such things happen during the rest of the month, but people usually do not associate them with any celestial events.

Various celebrations dedicated to the full moon are held in different parts of the world. One of the most popular is the "Full Moon Party" in Ko Pha Ngan, Thailand, attracting tens of thousands of tourists every full moon night. In Japan, this is tsukimi - admiring the full moon in September.

During the full moon, people notice pareidolic images: human faces, heads, silhouettes. These images actually consist of dark areas of the lunar seas (basalt plains) and lighter highlands on the lunar surface.

The Lunar Society of Birmingham, a club and unofficial learned society of eminent figures in the midlands of England, which met regularly between 1765 and 1813 in Birmingham, got its name from the fact that its members met exclusively during the full moon, since at In the absence of street lighting, their return home under the additional light of the moon was easier and safer.

The honeymoon is named after the full moon in June. Since it falls between planting and harvesting, this month has traditionally been considered the best for weddings.

In Sri Lanka, the full moon is sacred. According to legend, on the days of the full moon, the birth of the Buddha, his Enlightenment and the transition to nirvana took place. On the night of the full moon, all shops are closed, the consumption and sale of alcohol, sporting events and murders of any kind (including fishing) are prohibited.

Pagans believe that the most mystical time at Stonehenge is when the full Moon wanes, allowing the Earth to reunite with her lover, the Sun, at dawn.

While there is no evidence that a full moon directly affects our mental state, 80% of nurses and 63% of doctors said they see patients with mental health problems more often during a full moon than at any other time. This study was conducted by University Laval, Quebec, Canada.

There is a common misconception that the first Apollo landing took place during a full moon. In fact, it happened over a week later.