In order to study and know the endless numbers of outer space, astronomy is needed . This is the branch of science whose main objective is the study carried out with respect to the stars . Among the most important aspects that can be known , investigated and studied through it, we find from the different observation methods , the position , composition and movement of the celestial bodies, which many times can affect the planet. land. One of the terms used in astronomy is the aphelion, with which we refer to the most distant point that the orbit of a given planet has with respect to the sun.

What is aphelion?

It is called aphelion to the point of the earth’s orbit in which our planet earth is as far away as possible from the sun , which occurs because the earth does not have a circular path that is perfect, but on the contrary, it is elliptical.

Definition of aphelion

All the planets we know about our solar system are moving around the sun . These planets also have orbits and some of them are practically a pretty perfect circle, but in some cases they are not. Some of these planetary orbits have an oval shape or give the illusion that they are somehow stretched outwards are known to scientists as ” ellipses “ . If the orbit of a planet is a circle, the Sun is in the center of that circle. But when the orbit is in the shape of an ellipse, the Sun is at a point called «focus ‘ of the ellipse , which is not the same as the center.

Since the Sun is not the center of an orbit that is elliptical, as the planets rotate around the Sun, these same planets have the ability to move closer to or farther from the Sun. The place where a planet is most located far from the Sun it is known by the name of aphelion

The aphelion can be defined as the point that is located most distant from the orbit of a planet around the sun. It is also important to know that, as established in Kepler’s laws , the speed of translation that planet earth possesses is minimal in aphelion . We also know by this name the point of any body that has an elliptical orbit that is located farther from the body around which it is rotating .


The etymology of the word aphelion comes from the Greek language “αφ” (APH) of “απο” (apo) whose word meaning distant from, and ” ηλιος ” or helios which has the meaning sun . In astronomy it is a word considered as a masculine noun and that refers to the most isolated point that the orbit of a celestial body has around the sun.

How the aphelion influences the seasons

An important characteristic of aphelion, which was stated by Kepler in his famous laws, is that the Earth moves more slowly along its orbit during the summer period . For this reason, the duration of this season is much longer than that of the other seasons and the opposite happens in the southern hemisphere.  The aphelion is a phenomenon that occurs very close to the date of the beginning of summer.

It must be remembered that the earth stations do not have any kind of relationship with the distance that exists from the Earth to the Sun which could seem paradoxical at first glance because the sun is our main external heat source , which would make us think that the closer we are to him, the hotter we should be too.

The seasons are caused mainly by tilting shaft having the rotation of the Earth relative to the plane of its orbit about the sun . This axis is always located in the same direction and for this reason the northern and southern hemispheres are illuminated differently by the Sun depending on the time of year and receiving a different amount of sunlight that is related to the length of the day and with a different intensity depending on the inclination of the Sun on the horizon .

The aphelion of the different planets

All the planets of the solar system have different aphelia and according to different studies and measurements, these aphelion are the following:

  • Land: 152 million (1.1 AU)
  • Mercury : 70 million km (0.466 AU)
  • Venus : 109 million km (0.728 AU)
  • Mars : 249 million km (1.66 AU)
  • Jupiter : 817 million km (5.46 AU)
  • Saturn :  1.5 billion km (10.12 AU)
  • Uranus :  3 billion km (20.1 AU)
  • Neptune :  4.5 billion km (30.4 AU)

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