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lunar eclipse

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Throughout history, eclipses inspired awe and even fear , especially when total lunar eclipses turned the moon blood red , an effect that terrified people who did not understand what causes an eclipse and for this reason, they blamed the different gods they had in their times.

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What is a lunar eclipse?

lunar eclipse is a phenomenon of astronomy that happens when the Earth passes directly between the Moon and the Sun , causing the shadow of the Earth that is produced by the light of the Sun to be projected on the Moon.

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How is a lunar eclipse?

In our solar system , an eclipse occurs when a celestial object , such as a planet or the moon , passes between another planet or moon and its source of light, the sun . A lunar eclipse occurs when the Earth crosses between the moon and the sun, casting a shadow of the Earth on the moon.

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A lunar eclipse can only occur during the full moon and when the moon passes through the Earth’s shadow. The Earth has two types of shadows that are known as the umbra and the penumbra .

Shading of the moon by the Earth can produce a partial lunar eclipse , where only a portion of the moon is obscured by the gloom of the Earth. A total lunar eclipse occurs when the sun, earth, and moon are perfectly aligned, resulting in a complete darkening and / or reddening of the moon because direct sunlight is not reflected from the moon’s surface.

History:

Eclipses have been around since the world began. The oldest eclipse on record occurred in Babylon . All of them, in ancient times, were attributed to the gods and punishments for the peoples. The great astronomers , philosophers and writers of Greece were important observers of the phenomenon, which is why the historical records regarding eclipses are numerous .

The lunar eclipse of August 27, 413 BC influenced the Peloponnesian War ; the Athenians were ready to move their army over Syracuse when a total lunar eclipse was suddenly observed causing their enemies to retreat.

The Incas , the Mayas , the peoples of the Amazon , and countries around the world considered eclipses as punishments until astronomy began to develop and find scientific explanations for the phenomena that occurred in the sky .

Characteristics:

The main characteristics of a lunar eclipse are the following:

  • They only happen when there is a full moon .
  • The type and duration of a lunar eclipse depends on the position of the Moon.
  • A person can observe a lunar eclipse from anywhere where the moon can be observed and at night .
  • Depending on the position of the Moon in relation to the shadow of the Earth, three different types of eclipses can occur .

Types of lunar eclipse:

There are three different types of lunar eclipse which are:

  • Total lunar eclipse: it  happens when the entire moon passes through the earth’s threshold shadow . This means that the Moon completely enters the cone of the umbra . When they happen, the Moon goes through a following sequence of eclipses that includes: penumbral, partial, total, partial, and penumbral.
  • Partial lunar eclipse : in this type of eclipse, only one part of the moon enters the shadow of the threshold that the earth has and the other part remains in the penumbral zone .
  • Penumbral lunar eclipse : here the moon only passes through the penumbral . It is one of the most difficult eclipses to see because the shadow that occurs on the moon is very subtle and diffuse . In this type of eclipse we can find two different ones, one the total penumbral eclipse when the moon is completely within the penumbral zone, and a partial penumbral eclipse when only one part of the Moon is within the penumbra and the other is without shadow.

Phases:

The phases that occur during a lunar eclipse are the following:

  • Beginning of the penumbral eclipse : it occurs when the moon comes into contact with the outer part of the penumbra causing one part to be inside the penumbra and the other outside.
  • Beginning of the partial eclipse : it occurs when the moon has one part in the threshold zone and the other in the penumbral, which gives rise to the partial eclipse.
  • The total eclipse begins: when the moon is totally in the threshold zone.
  • Maximum phase : when the moon is in the center of the umbra.
  • End of the total eclipse : it happens when the moon comes into contact with the other side of the penumbral zone, giving rise again to a partial eclipse, ending the total eclipse.
  • End of the partial eclipse : when the moon leaves the threshold zone to enter the twilight, thus initiating a penumbral eclipse again.
  • End of penumbral eclipse : it happens when the moon leaves the penumbral in its totality, which indicates that the eclipse has ended.

Why it occurs?

Lunar eclipses occur because the moon enters the cone of shadow of the earth whose length is much greater. These eclipses occur when there is a practically perfect alignment between the sun , the earth and the moon , projecting the shadow on the satellite when it is in the full moon phase.

How to see a lunar eclipse?

Observing a lunar eclipse is completely safe so you will not need any type of protection to observe it, since what is observed is a projection of the sun on the moon, which is why there are no risks of damaging the eyes. Binoculars or telescopes can also be used . And finally, the ideal is to look for a place that is far from the light pollution produced by the lights of the big cities, so the mountains or places far from the cities are the best places to observe them.

How long does it last?

The lunar eclipse is the position depends on having the moon relative to its orbital nodes , which are the points where the orbit of the Moon crosses the plane of the orbit of the sun . So generally , a total lunar eclipse lasts 30 minutes s to 1 hour , but may extend a few hours.

When will be the next?

For this year 2018, we will only see a lunar eclipse that will happen on July 27 and it will be a total lunar eclipse . This incredible event can be seen mainly in the eastern hemisphere , which involves parts of Europe , Asia, Africa and Oceania . The total eclipse, with all its partial phases, will last approximately four hours .

How it differs from a solar eclipse?

Solar eclipses happen when the Moon passes in front of the Sun and blocks part of its view. They happen only during the day and only when the moon is in the new moon phase. When they are total they cannot be observed with the naked eye.

Lunar eclipses are the opposite, they happen when the Moon is located in front of the Earth, crossing its shadow, causing part of the Moon to be covered with darkness . These eclipses are very easy to locate with the naked eye and do not require the use of a telescope . They can be observed without danger even if they are total eclipses.

Importance:

Eclipses have been important to scientific development for thousands of years. Thanks to them, the distance from the Earth to the Moon was determined for the first time by means of a total lunar eclipse. The equinoxes were also discovered and Aristarchus’ determination of the distance from the Earth to the Moon was improved. Kepler also proposed using lunar eclipses as an absolute signal to measure the geographic longitude of a place on Earth.

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