Why will the lunar eclipse of 27/7/2018 be unusually long?

The longest eclipse in the twenty-first century will happen on July 27 (midnight on the morning of July 28, Vietnam time), with a time of 1 hour, including 43 minutes of maximum when Face Moon faces Africa, the Middle East and Central Asia. If from the moment the Earth's shadow began to darken the edge of the Moon until the time when the Moon returned to normal, it would take 4 hours.

Meanwhile, the next possible eclipse from North America will occur on January 21, 2019, but only lasts a total of 1 hour 2 minutes; The last lunar eclipse occurred in August 2017 when the Moon faced 14 states in the United States in turn, only within 2 minutes and 40 seconds.

So what is the reason why the amount of eclipses and eclipses vary so much?

Solar eclipse is when the Moon is between the Sun and Earth and always has a shorter time than the lunar eclipse. According to Ms. Kaisa Yong - Astronomer at Nicholls University, USA, the eclipse is shorter than the lunar eclipse because of the difference in the size of these three bodies creating different shadows . Suppose we stand in outer space to look, when there is an eclipse, the moon's shadow is printed on the planet larger than it, and when there is a lunar eclipse, the shadow of the big planet obscures the smaller Moon.

Solar eclipse is shorter than the lunar eclipse due to the size difference of the Moon, Sun and Earth.

When there is a solar eclipse, the darkness is entirely due to the Moon imprinting on Earth just a few dozen kilometers wide and passing through the Earth very quickly; but when the lunar eclipse, the Earth's shadow is larger and covers the Moon, making the Moon take longer to escape the shadow , especially on the lunar eclipses the Moon passes through the middle of the dark. instead of just going through the edge.

There are also significant differences between eclipses and between eclipses. This is due to the patterns and movements of the celestial bodies.

Earth, Moon and Sun have no absolute similarities. The Moon's orbit is about 5 degrees, and in each of its 27-day orbit, the Moon only passes through the same plane as the Earth and the Sun have twice. This is the basic form that makes the planets obscure each other.

On average, every 11 months, there are 2 times this celestial body is aligned with each other, in which one is eclipse and one is eclipse. That is why the phenomenon of obscuring each of these three bodies often occurs in pairs, each pair consists of an eclipse and a lunar eclipse 2 weeks apart and why each year usually has 4 obscures. .

However, it is not always the same every time, because every 11 months is not exactly the same. Sometimes relative alignments occur and the shadow area only partially obscures part of the Earth or part of the Moon. That was the phenomenon that happened on July 13 when the eclipse partially covered the southern edge of Australia and the waters near Antarctica. The real moon here on July 27 is the couple of the eclipse.

In the third time the celestial object is almost perfectly aligned, the Moon passes through the center of the Earth's shadow, in other words the shadow of the Moon passing through the Earth's equator, creating a longer obstruction time.

The time of year also affects the eclipses of eclipses.

The last factor affecting the period of obscurity is the time of the year . In July, the Earth is at the farthest point of the Sun and looks the smallest in the sky compared to other times of the year. This means that both the Earth and the Moon have a bigger shadow than usual and any obscured object will take longer to get out of that shadow. The Earth is closest to the Sun in January, so at this time the Earth will be a big star in the sky and shadow when eclipses and eclipses will be smaller.

That is why the longest eclipse of the eclipse usually occurs at the time of summer and the shortest in the winter in the northern hemisphere.

The real moon on July 27, 2018 will be the time when the Moon passes through the center of the Earth's shadow and will be the longest period of the century.