Earth is about to reach its farthest position from the sun, a phenomenon known as aphelion. This is the maximum cut-off point It puts us roughly 152 million kilometers away from the king of stars.
Video: Curiosity about the Sun
This year, in 2023, our cosmic rendezvous with the aphelion will occur on July 6 at 20:08 UTC (22:08 in Spain, 14:00 in Mexico City). This recurring but always fascinating annual event arouses curiosity and raises many questions.
Avilio: Why is that happening?
To understand the aphelion, it is necessary to know how our planet moves. The earth revolves around the sun in a movement that takes about 365 days. This path is not a perfect circle, but an elliptical orbit, a theory formulated by the famous German astronomer Johannes Keplercontemporary Galileo Galilei.
The result of this elliptical orbit is that there are times of the year when the Earth is closer to the Sun, and other times when it is further away. When Earth is closest, we are at perihelion, a point we usually reach in early January, when our planet is It is located at a distance of at least 147 million km from the Sun.
In contrast, aphelion, a term derived from the Greek words “apo” (far from) and “helios” (sol), is the point at which we are farthest from the Sun.
Effects of afilium
Despite the difference in distance, the global temperature variation is practically imperceptible due to the latitude and axial tilt of the Earth.
What is happening is that the speed of the Earth is changing. As counterintuitive as it may seem, the Earth moves slower in its orbit when it is farther from the Sun (at aphelion) and faster when it is closer (at perihelion). During perihelion, the Earth is moving at a speed of 30.29 km/sec, while at aphelion, the Earth is moving at a speed of 29.29 km/sec.
This is due to Kepler’s first law, also known as the law of equal areas, which states that the radius vector connecting a planet and the sun sweeps through equal areas in equal times.
Why is it hotter?
The fact that Earth is farthest from the Sun during the northern summer might seem like a contradiction at first. Shouldn’t summer coincide with our closest position to the sun? Surprisingly, the answer is no. The sequence of seasons is not governed by the distance from the earth to the sun.
Oscillations in our orbit between 147 and 152 million km, which correspond respectively to perihelion and aphelion, are not sufficient to change the flow of the seasons. Therefore, even if we reach the apogee in the middle of summer in the northern hemisphere, this does not prevent us from experiencing high temperatures. together, The southern hemisphere is experiencing winter, despite being at the same distance from the sun.
The seasonal variation is not due to the distance from the Earth to the Sun, which, as mentioned, does not fluctuate enough to affect the global climate. Instead, the seasons are the product of the tilt of our planet’s axis in relation to the sun.
The earth follows its elliptical path around the sun with an inclination of approximately 23 degrees with respect to the perpendicular to the plane of its orbit. Throughout the year, this characteristic tilt results in unequal exposure of different parts of the planet to sunlight.
During summer in the northern hemisphere, the sun’s rays hit that hemisphere at a more direct angle and for a longer period, while in the southern hemisphere, The sun’s rays arrive at a more oblique angle for a shorter period.
It is this pattern of solar illumination that determines the alternation of the seasons, and causes important astronomical events such as the equinoxes and solstices. So, despite our varying distances from the sun, it’s the sun’s rays angles that really determine the changes in our seasons.
It happens with other planets
Earth is not the only planet with aphelion and perihelion: all planets in our solar system have aphelion (farthest from the sun) and perihelion (closest to the sun) because all planets’ orbits are elliptical. .
The difference between these points can be greater or smaller depending on how elliptical the planet’s orbit is.
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