An interesting phenomenon can be observed annually. It is worthwhile to figure out whether the brightness of stars really depends on the time of year, and what other reasons are there for such changes?
The position of the sun at different times of the year
In fact, the time of year does not directly affect the appearance of the starry sky. However, seasonal decrease and increase in brightness is not an illusion, but the result of visual perception. Change does not occur with the stars, but with the "background" on which they are located. In other words, the color of the sky changes.
City dwellers are unlikely to notice any changes, because starlight sky is a rare phenomenon due to light pollution over large settlements. Best of all, a change in the brightness of stars is noticeable outside the city or in small towns and villages. The color of the night sky changes depending on the time of year. In winter, it usually looks much darker than in summer. This is directly related to the peculiarities of sunrise and sunset and, accordingly, the rotation of the Earth around the star.
Planet Earth orbits the sun. It does not have an even round shape, but rather resembles an elongated ellipse. In this case, the Sun is not located in the middle, but a little on the side. During rotation, the planet constantly changes its distance in relation to the Sun - it becomes closer, now further. A full turn takes 365 days.
The minimum distance between the Earth and the Sun is observed in January and amounts to 147 million km. This phenomenon has a special name - “perihelion”, which denotes the point of the Earth’s orbit closest to the Sun. During the maximum approach of the Earth, most of the light enters the southern part of the globe, so summer begins there.
At the greatest possible distance from the Sun, the planet appears around July. At the same time, the distance is 152 million. The point of the Earth’s orbit farthest from the Sun also has its own name - “aphelion”. During this time period, sunlight receives the northern part of the globe. Summertime begins here, while winter reigns in southern countries.
Interesting fact: if the Earth did not make constant deviations and approximations, the seasons would never change on the planet. In one part of the ball there would always be winter, in the other - spring, in the third - autumn, etc. It is the slope of the conditional axis of the planet that is the main reason for the changing seasons. Otherwise, the Earth would always be at the same distance from the Sun.
How does the sun shine at different times of the year?
The remoteness of the Earth from the Sun, as well as the angle of inclination with respect to the star, are the causes of varying degrees of illumination. The axis of the Earth is the main factor that affects the change of seasons. While the planet revolves around a star, at the same time, it makes one revolution every 24 hours around its own conventional axis. The angle of inclination of this axis in relation to the Sun is 23.5 degrees. She always "looks" at the North Star.
There are also special days - the equinox and solstice. The equinox (spring and autumn) is a phenomenon during the transition of the Sun from one hemisphere to another. In this case, the day lasts almost as much as the night, and the earth's equator is in direct sunlight. The entire surface of the planet is lit equally.The solstice day is summer with the longest day or winter - with the longest night of the year. In the first case, the Sun is at the maximum height above the horizon, and in the second, at the lowest possible.
Thus, it becomes clear why in winter the night sky takes on a darker color. During this period, the Earth is at a relatively small distance from the Sun. Accordingly, it rotates in an orbit of a smaller radius - the Sun goes "further" beyond the horizon and the sky becomes dark. The Milky Way, the Moon, and stars are clearly visible on it. In summer, the sun is located high above the horizon. The Earth rotates over a larger radius, and the star is not very deep below the horizon. Therefore, in summer, the night seems more illuminated, and stars and other astronomical objects are less visible in the twilight sky.
Interesting fact: at the poles of the Earth, all these phenomena occur differently. The South and North Poles are exposed to the rays of sunlight in turn. Thus, there lasts 6 months night, and the next 6 months - day.
The brightness of stars is affected not by the season, but by the color of the sky. In summer, the night sky looks brighter due to the fact that the Earth at this time of year is at a greater distance from the Sun. The star turns out to be shallow beyond the horizon, so the sky takes on twilight tones at night - the stars are poorly visible. In winter, the planet is closer to the Sun, so it falls below the horizon. The sky takes on a deep dark shade, and the stars on it look brighter.
