Definitions of Aphelion


The notion of aphelion is used in the field of astronomy. It is the most distant point of the orbit of a particular planet about the sun. This means that, when a certain planet is in its aphelion, it is located as far from the Sun as it will become while it orbits.

The opposite of aphelion is perihelion: the point on the orbit that is closest to the Sun. These two points are known as apsidales points. According to physical laws, in the aphelion the planet moves at its minimum speed, while in the perihelion it reaches its maximum translational speed.

In the case of planet Earth, the aphelion occurs at the beginning of July. In this instance, the Earth is located 152.1 million kilometers away from the Sun. In early January, on the other hand, the Earth passes through its perihelion, being located 147.09 million kilometers from the solar star.

It is important to note that the notion of aphelion always refers to the distance of the planet from the Sun. On the other hand, when you want to refer to the most distant point from the planet Earth, you are talking about apogee. If the consideration intends to be made on other stars, the generic term used is apoastro.

Because the continental surfaces and the oceans are not evenly distributed on our planet, the warmest temperatures in the northern hemisphere occur in the aphelion, when the distance from Earth and the Sun is very wide. This is because there is more continental surface in the northern hemisphere, which is then tilted towards the Sun.

Aphelion, perihelion and the order of the seasons

Year after year, at the beginning of January, our planet goes through the perihelion of its orbit, and scientists always record the exact moment in which this takes place. Although it would seem logical to assume that at this point in its trajectory the Earth is at the highest temperature, since it is when it is closest to the Sun, this is only true for the southern hemisphere: in the north, January is the most winter cold.

This leads us to the following conclusion: the stations of the Earth are not linked to the distance that it maintains with its star, although throughout its route it varies by five million kilometers, as explained above. What happens is that during the perihelion, the north pole is on the opposite side to the Sun, given the rotation of the Earth, and for this reason the days there are shorter and the amount of light that comes in is less, in addition to do it especially tangentially.

In this way, although the planet is at its closest point to the Sun, the northern hemisphere receives less heat than the rest of the year; in the south, on the other hand, the situation is clearly opposite, since the days last longer, the temperature reaches its highest peaks and the light bathes its extensions directly. It is worth mentioning that from a global point of view, given that in the northern hemisphere there is more terrain than in the south, and that the earth heats up more easily than water, the total temperature of the Earth is higher during the aphelion than in perihelion.

Therefore, knowing the distance at which our planet is from the Sun at a certain moment in its trajectory is not enough to deduce its temperature, which is a phenomenon with little apparent effects.