Everything in this life begins with a rotation, everything ultimately comes into its own. It all starts with movement. Cosmos is no exception, its knowledge begins with the rules and order of movement in space of all its objects. This mechanism has a complex organization.
Orbit - a difficult circle ...
From birth, all people know that cosmic bodies, primarily planets, rotate in an orbit, which is a circle. But in this case, this is a relative concept. The fact is that not a single circle along which the cosmic body passes its path around the Sun is ideal. To one degree or another, they are all close to an ellipse. Such distortions give all the planets an additional unique component, because in each part of the orbit, the Sun will affect them differently, sometimes significantly affecting the climate and other indicators. This effect is especially noticeable at two points. Which ones?
Aphelion and perihelion
These are sections of any orbit that are located on its opposite sides. The distortion of the circle leads to the fact that the planet may be closer or further from the Sun.
What is perihelion?
This is the point where the planet, comet or asteroid is at the smallest distance from the sun. Such moments for some of them may be considered a full summer, while for others they may not bring much change.
For example, on Earth, the difference between the minimum and maximum distances is relatively small, only 5 million km. Therefore, these periods people do not even notice. However, for clarification, it is worth noting that the Earth passes perihelion on January 4-5 annually. In the northern hemisphere at this time is the height of winter, and in the southern hemisphere is quite ordinary summer.
And if you imagine that it would be possible to be on Mercury, you could feel the difference, because its orbit is much more different from an even circle. As for the Earth, the moments of closest approach are not relevant for Venus, Jupiter, Saturn, Uranus and Neptune.
Aphelion
At this point in the circle, the space object is maximally distant from the Sun. It does not matter for all those planets mentioned in the previous section. It is worth noting that in fact the name "aphelion" appeared later. Initially, this point was called "apogelium." It’s just that once upon a time someone decided to divide a word into two parts in records, having reduced it: ap.helios. When reading the dot between the parts of the word was not noticed, and someone read the combination of letters ph as "f", as it is read in English. Since then, the name "aphelion" has entered and entrenched in various languages. Every year the earth passes this point on July 4-5.
These orbital centers are important points not only for astronomers, perihelion and aphelion in astrology, too, occupy not the last place. They are used to make predictions and predictions of global events.
And what distinguished the orbits of Mercury, Mars and Pluto?
Yes, nothing special, except that their orbits are stronger than the others differ from the circle and more resemble a full-fledged oval. So, the moments when they pass aphelion and perihelion are especially important for them.
Mercury
The range of distances from the star is quite wide - from 46 to 70 million km. This planet has no seasons, because its axis has almost no slope, however, you can notice a significant change in daytime temperature. When Mercury is at a maximum distance from the Sun, the temperature in daylight is less than + 300 degrees Celsius, and at times of maximum convergence it increases to almost + 430.
Mars
Its orbit is more rounded compared to the Mercury one. But significant changes in the periods of passage of aphelion and perihelion still occur. They are manifested by the fact that the seasons in one hemisphere will differ from the other in duration and temperature. When summer begins in the northern hemisphere, the planet is at a maximum distance, so it is not so warm, but longer. In the south, on the contrary, it is shorter, but warmer, because Mars passes perihelion during this period.
As for temperatures, it is difficult to talk about them, because they change dramatically not only with respect to winter and summer, but also during the day, which are almost identical to earthly ones. For example, at the equator during the day the planet can warm up to +28 degrees, but even at night the temperature can drop to -40 or lower. The minimum temperature at the poles is close to -150 degrees.
Pluto
It has its own paradoxical features. Orbit is one of them. It is almost as oval as Mercury. The point of closest distance is at a distance of almost 50 distances from the Earth to the Sun, and when approaching a star, Pluto is closer than Neptune, at that time 29 distances from the Earth to the Sun separate it from the star.
Although it intersects with Neptune, it cannot collide with it, due to the different inclination of their orbits.
Planet nodes
These are the points where the planet’s orbit crosses the celestial equator when moving from south to north and back. They have no special significance. However, the nodes of the moon are popular with astrologers, who consider them important karmic points and use them in interpreting the horoscope. By their location, the optimal path of personality development is determined. Believe it or not - everyone decides for himself.
Astronomically, the lunar nodes are the points of eclipses that occur when the night star at the moments of a new moon or full moon coincides with one of them.
Conclusion
Any way is full of mysteries and surprises, especially when it comes to planets. In this case, a simple circle is a storehouse of interesting information. Knots, perihelions and aphelions help to create a more complete picture of the concept of orbit.