Diversity of calendars arose historically. The need to measure time is intertwined with beliefs, traditions, and habitat. As a result, number systems of years have arisen that not only start with different days, but also count the number of days in a year in different ways.
What happened before the astronomical year
Almost all peoples used the moon and the sun as reference systems for time intervals. The most natural unit was the day, which was regularly replaced by night. But there were other periods that could not be overlooked.
Winter, spring, summer and autumn followed each other with the constancy of the rotation of the spokes of the wheel. It was impossible not to connect them with the phases of the moon and the duration of the sun's stay in the sky. Thousands of years of observing the movements of heavenly bodies passed until the concept of the year appeared.
"The sun shines the same for everyone." The once fashionable song explains well why the length of the year in different calendars is almost the same. The difference in a few days in everyday life is not fundamental. The starting point is even more so: some from Jesus, others from Krishna, and still othersfrom earthly deities, kings.
New Year from an astronomical point of view
Science of the stars could not accept such diversity. Humanity has become more and more united. What was needed was a monotonous and scientifically substantiated theory of daily and seasonal periods. This problem was solved by introducing the concept of an astronomical year.
The change of day and night has since been explained by the movement of the Earth around the Sun. The time of a complete revolution along the ecliptic began to be called a year, it remains to appoint a reference point. Here the scientists acted in the same way as the priests and priests. We chose a day. He marked the astronomical new year.
Four points in orbit
The day was chosen arbitrarily, but not by chance. On the trajectory along which our planet moves around the Sun, there are four remarkable points. Two of them are called the days of the equinox - spring and autumn. Others - the days of the winter and summer solstices. When the Earth is in one of them, the maximum difference between the length of day and night is reached.
The choice was not rich, so it was not difficult. In northern latitudes, this event occurs on December 21 or 22. It turns out that the beginning of the astronomical year "floats". It must be understood that in fact this is not a day, but the moment when the inclination of the Earth's axis of rotation reaches its maximum value of 23° 26´.
It's amazing that people attached great importance to this day in the Neolithic. Ancient structures such as Stonehenge and Newgrange were oriented so that the observer could see the sun throughaxial hole only on the day of the winter solstice.
The astronomical year begins on this day, partly because in almost all cultures it was given the meaning of rebirth, beginnings. Hades, the ruler of the underworld, was allowed to come into the light. The Japanese goddess Amaterasu emerged from a cave, symbolizing the birth of a new sun.
Events of the current year
Like any other, the astronomical calendar for the year lists significant events. There are no holidays or weekends here. But there is:
- dates of lunar and solar eclipses;
- observation capabilities for asteroids, comets and meteor showers;
- favorable time for the visibility of the planets, their conjunction;
- lunar occultation of stars and planets.
This year we are waiting for several eclipses: three solar and two lunar. All of them can be observed from the territory of Russia.
The brightest asteroid in 2019 will be Vesta. Its brilliance during its stay in the constellation Cetus will be such that it will be possible to observe with the naked eye. Other asteroids, Bleska and Pallas, will only be visible through a telescope.
For lovers of astronomy, the calendar contains tables and other reference data on the starry world around us.
Time or distance?
Science, among other varieties, also includes such types of the year as:
If about the firstthree types is rarely mentioned, then the astronomical light year is familiar to everyone at least by ear. Fantasy novels contributed to his recognition. But not everyone knows that this concept defines not a time period, but a distance.
Stars and planets are too far apart to use the usual measures of length. We are separated from the Moon by 384 thousand kilometers, which is not far from zero on a cosmic scale. The development of astronomy required units of measurement corresponding to the vastness of the universe.
When it was possible to accurately measure the speed of light, it became possible to apply it to measure gaps in planetary systems. Its main advantage is that it is constant. Therefore, we agreed that the distance that light travels in 1 year will be the standard of length for astronomers.
Measuring in light units gives: 1.28 seconds to the Moon, 8 minutes to the Sun, 4.2 years to the nearest star.
The beginning of the astronomical year is the winter solstice, interesting because:
- it happens 2 times a year;
- falls on different dates in different countries;
- this is the wrong term.
Features of the winter and summer solstices are explained by the inclination of the earth's axis to the plane of the celestial equator and the fact that they last only a moment. The winter solstice in the Northern Hemisphere is summer for the Southern Hemisphere and vice versa.
And as for the incorrectness of the term, it came to us in those days when the Earthconsidered the center of the universe. Everything revolved around her: the planets, the Sun, the stars. Therefore, the only moment of the immobility of the sun was called the solstice. Copernicus got rid of this delusion, but the name remains.