Why will the Earth move slower by 7,000 km / h this July 6

July 3, 2018 22:49
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Updated on July 3, 2018 22:49

This Friday, July 6th, we will be at our furthest point from the Sun in 2018.

On that day, the Earth will cross what is called aphelion, word of mouth. Greek origin meaning "far from the sun"

"The aphelion is the point of Earth's orbit around the Sun in which the Earth is farthest from our star and perihelion (near the Sun) is the opposite point, that is to say the point of the orbit of the Earth.The Earth is closer to the Sun, "BBC Mundo Nayra Rodríguez Eugenio, astrophysicist and disseminator of The Institute of Astrophysics of the Canaries

"In perihelion the Sun is about 147 million km from Earth, and when it is in the aphelion, it is about 152 million km of the Sun. "

The distance varies because the Earth's orbit around the Sun is not a perfect but elliptical circumference.

NASA [1965900] 3] In the aphelion, "the Earth is a little further, 5 million kilometers further from the Sun," than in perihelion.

Speed ​​

The aphelion takes place every year between July 2nd and 7th. Perihelion took place this year on January 3rd.

The distance varies because the orbit of the Earth around the Sun is not a perfect but elliptical circumference. NASA

The greatest distance between the Earth and the Sun will be recorded on July 6 at 17:46 GMT, when the planet and its star are 152,095,566 km.

The greater distance is translated into As the second law of Keple indicates, when the planets are close to the Sun in their orbit, they move faster than when they are farther apart.

The greater distance in aphelion means that the orbital velocity of the translation will be less than 103.536 km / h, or more than 7.000 km / h less than the speed of perihelion.

Seasons

The greater or lesser distance to the Sun during aphelion or perihelion is not They relate to temperature changes during the seasons.

"The seasons are produced by tilting the axis of rotation of the Earth in relation to the plane that it describes around the Sun, what we call the ecliptic," explains Rodríguez Eugenio [19] 659003] "This axis is inclined at about 23.5 degrees and so when we are in the northern hemisphere summer, the north axis, it is to say the North Pole of the Earth, points more toward the direction of the Sun. "

"In contrast, in winter, our north pole points in the opposite direction, this is not exactly the opposite because it is about 23.5 degrees, but it is oriented to the opposite of the sun . "

More water in the southern hemisphere

The summer of the northern hemisphere coincides with the aphelion, "but we receive more solar radiation here in the northern hemisphere because the sun is higher above the horizon and we also have more hours of sunshine "astrophysics.

"In the southern hemisphere, there is more water than in the northern hemisphere and this means that the temperature does not increase as much", explains Rodríguez Eugenio. NASA

In the southern hemisphere, summer coincides with perihelion

"This could make us think that in the southern hemisphere the temperature rises more than north in summer, because aside from the inclination, The Earth is also closer to the Sun ", explains Rodríguez Eugenio

But this is not the case

What happens is that" in the l & # 39; The southern hemisphere there is more water and it does not increase the temperature ".

"This seems to be because the earth warms up much more easily than water and, because the southern hemisphere has a greater proportion of its surface covered with water, the water is more easily absorbed. excess energy is absorbed by it. "

Therefore, in summer, both in the southern hemisphere and in the northern hemisphere, the temperature is about the same, explains astrophysics.