In popular science articles on space and astronomy, one can often find the not-so-clear term “ecliptic”. This word, in addition to scientists, is also often used by astrologers. It is used to indicate the location of space objects remote from the solar system, to describe the orbits of celestial bodies in the system itself. So what is an ecliptic?
What does the zodiac have to do with it
Even the ancient priests who watched the celestial bodies noticed one feature of the behavior of the Sun. It, as it turned out, moves relative to the stars. Tracking its movement across the sky, observers noticed that exactly one year later the Sun always returns to its starting point. Moreover, the “route” of movement from year to year is always the same. It is also called the "ecliptic." This is the line along which our main body moves through the sky during the calendar year.
The stellar areas through which the path of the shining Helios ran in its golden chariot harnessed by golden horses did not go unnoticed (as the ancient Greeks imagined our native star).
A circle of 12 constellations, along which the Sun moves, was called the zodiac, and these constellations are usually called zodiac.
If by the horoscope you are, say, Leo, then do not look for this constellation in the sky at night in July, the month in which you were born. The Sun is in your constellation during this period, which means that you can see it only if you are lucky to catch a total solar eclipse.
Ecliptic line
If we look at the starry sky during the day (and this can be done not only during a total solar eclipse, but also using a conventional telescope), we will see that the sun is at some specific point in one of the zodiac constellations. For example, in November, this constellation will most likely be Scorpio, and in August - Leo. The next day, the position of the Sun will shift slightly to the left and this will happen every day. And a month later (November 22), the star will finally reach the border of the constellation Scorpio and move to the territory of Sagittarius.
In August, it is clearly visible in the figure, the Sun will be within the boundaries of Leo. And so on. If every day we mark the position of the Sun on a star map, then in a year we will have in our hands a map with a closed ellipse printed on it. So this very line is called the ecliptic.
And when to watch
But to observe their constellations (zodiac signs under which a person is born) will turn out in the month opposite the date of birth. After all, the ecliptic is the route of the movement of the Sun, therefore, if a person is born in August under the sign of Leo, then this constellation is located high above the horizon at noon, that is, when sunlight does not allow him to see.
But in February, Leo will adorn the midnight sky. On a moonless cloudless night, he perfectly "reads" against the background of other stars. Not so lucky born under the sign of, say, Scorpio. The constellation is best seen in May. But to consider it, it is necessary to stock up on patience and good luck. It is better to go to the countryside, in an area without high mountains, trees and buildings. Only then will the observer be able to make out the outlines of Scorpio with its ruby Antares (alpha of Scorpio, a bright star of blood-red color belonging to the class of red giants, having a diameter comparable to the size of the orbit of our Mars).
Why is the expression “ecliptic plane” used?
In addition to describing the stellar route of the annual motion of the Sun, the ecliptic is often regarded as a plane. The expression "ecliptic plane" can often be heard when describing the position in space of various space objects and their orbits. Let’s figure out what it is.
If we return to the pattern of movement of our planet around the mother star and the lines that can be drawn from the Earth to the Sun at different points in time, put together, it turns out that they all lie in the same plane - the ecliptic. This is a kind of imaginary disk, on the sides of which are all 12 described constellations. If you draw a perpendicular from the center of the disk, then in the northern hemisphere it will rest against a point on the celestial sphere with the coordinates:
- declination + 66.64 °;
- right ascension - 18 hours
And this point is located not far from both “dipper” in the constellation Dragon.
The axis of rotation of the Earth, as we know, is tilted to the axis of the ecliptic (23.44 °), so there is a change of seasons on the planet.
And our "neighbors"
Here is a brief summary of what the ecliptic is. In astronomy, researchers are also interested in how other bodies of the solar system move. As calculations and observations show, all the major planets revolve around the sun almost in the same plane.
The planet closest to the star, Mercury, is knocked out of the overall coherent picture most of all, the angle between its plane of rotation with the ecliptic is as much as 7 °.
Of the planets of the outer ring, Saturn’s orbit (about 2.5 °) has the largest angle of inclination, but given its enormous distance from the Sun - ten times farther than the Earth, the solar giant is forgivable.
But the orbits of smaller cosmic bodies: asteroids, dwarf planets and comets deviate much more from the ecliptic plane. So, for example, the dwarf planet, the double of Pluto, Eris has an extremely elongated orbit.
Approaching the Sun at a minimum distance, it flies closer to Pluto, by 39 a. e. (i.e., an astronomical unit equal to the distance from the Earth to the Sun - 150 million kilometers), in order to then retire to the Kuiper belt again. Its maximum removal is almost 100 a. e. So her plane of rotation is inclined to the ecliptic by almost 45 °.