It is rare that natural or astronomical phenomena, in terms of the strength of their drama and impact on humans, can surpass a solar eclipse. Understanding its internal processes and hidden mechanisms will allow you to broaden your horizons, take a step into the world of star science. There can be two such periods during one calendar year, i.e. at least 2 eclipses in 365 days. Moreover, during each period there may be several such phenomena, but not more than 5 per year, in different parts of the globe.
The mechanism and time of a solar eclipse
Descriptions of how a solar eclipse occurs have generally remained unchanged over the entire documented history of observations. At the edge of the Sun, a dark spot of the lunar disk creeping to the right appears, which gradually increases in size, becomes darker and clearer.
The larger the surface of the star is covered by the Moon, the darker the sky becomes, on which bright stars appear. Shadows lose their usual outlines, become blurry.
The air gets colder. Its temperature, depending on the geographical latitude along which the eclipse strip passes, can decrease by up to 5 degrees Celsius. Animals at this time become anxious, often rushing about in search of shelter. The birds become silent, some go to bed.
The dark disc of the Moon is creeping more and more onto the Sun, leaving an increasingly thinning sickle from it. Finally, the Sun disappears completely. Around the black circle that closed it, you can see the sun's crown - a silvery glow with blurred edges. Some illumination is given by the dawn flashing all over the horizon around the observer, an unusual lemon-orange hue.
The moment of complete disappearance of the solar disk usually lasts no more than three to four minutes. The maximum possible time of a solar eclipse, calculated using a special formula, based on the ratio of the angular diameters of the Sun and the Moon, is 481 seconds (slightly less than 8 minutes).
Then the black lunar disk shifts further to the left, exposing the sun's blinding edge. At this moment, the solar corona and the glowing ring disappear, the sky brightens, the stars go out. The gradually liberating Sun gives off more and more light and heat, nature returns to its usual form. It is important to note that in the northern hemisphere, the moon moves along the solar disk from right to left, and in the southern hemisphere, on the contrary, from left to right.
The main types of solar eclipses
The area of the globe over which the above can be observed total solar eclipse, is always limited by a narrow and long strip that forms in the path of the cone-shaped shadow of the Moon, sweeping across the earth's surface at a speed of more than 1 kilometer per second. The width of the strip usually does not exceed 260-270 kilometers, in length it can reach 10-15 thousand kilometers.
The orbits of the Earth's motion around the Sun and the Moon around the Earth are ellipses, so the distances between these celestial bodies are not constant values and can fluctuate within certain limits. Due to this principle of natural mechanics, solar eclipses are different.
At a much greater distance from the total eclipse strip, one can observe partial solar eclipse, which in common parlance is often also called partial. In this case, for an observer who is in a place outside the strip, the orbits of the night and day luminaries intersect in such a way that the solar disk is only partially closed. Such phenomena are observed much more often and over a much larger area, while the area of a solar eclipse can be several million square kilometers.
Partial eclipses occur annually in almost every point of the globe, but for most people outside the professional astronomical community, they go unnoticed. A person who rarely looks at the sky will see such a phenomenon only when the Moon covers the Sun by half, i.e. if the value of its phase approaches 0, 5.
The calculation of the phase of a solar eclipse in astronomy can be performed using formulas of varying degrees of complexity. In the simplest version, it is determined through the ratio of the diameters of the part closed by the Moon and the total diameter of the solar disk. The phase value is always expressed as a decimal fraction only.
Sometimes the Moon passes from the Earth at a distance slightly greater than usual, and its angular (apparent) size is less than the apparent size of the solar disk. In this case, annular or annular eclipse: the sparkling ring of the Sun around the black circle of the Moon. At the same time, observation of the solar corona, stars and dawn is impossible, since the sky practically does not darken.
The width of the observation strip with a similar length is much higher - up to 350 kilometers. The penumbra width is also greater - up to 7340 kilometers in diameter. If during a total eclipse, the phase is equal to one or maybe even more, then with an annular eclipse, the phase value will always be greater than 0.95, but less than 1.
It is worth noting an interesting fact that the observed variety of eclipses falls just on the period of the existence of human civilization. Since the formation of the Earth and the Moon as celestial bodies, the distance between them is slowly but continuously increasing. With changing distances, the scheme of a solar eclipse as a whole remains the same, similar to that described above.
More than a billion years ago, the distance between our planet and its satellite was less than it is now. Accordingly, the apparent size of the lunar disk was much larger than the size of the sun. There were only total eclipses with a much wider shadow band, observation of the corona was nearly impossible, as was the formation of annular eclipses.
In the distant future, millions of years later, the distance between the Earth and the Moon will become even greater. The distant descendants of modern mankind will be able to observe exclusively annular eclipses.
Scientific experiments for amateurs
Observing eclipses of the Sun at one time helped to make a number of significant discoveries. For example, even in the days of the ancient Greeks, the then sages drew conclusions about the possible movement of heavenly bodies, their spherical shape.
Over time, research methods and tools made it possible to draw conclusions about the chemical composition of our star, about the physical processes taking place in it. The well-known chemical element helium was also discovered during the eclipse observed by the French scientist Janssen in India, in 1868.
Solar eclipses are one of the few astronomical phenomena available for amateur observation. And not only for observations: anyone can make a feasible contribution to science and record the circumstances of a rare natural phenomenon.
What an amateur astronomer can do:
- Mark the moments of contact between the solar and lunar disks;
- Fix the duration of what is happening;
- Sketch or photograph the solar corona;
- Participate in an experiment to refine the data on the diameter of the Sun;
- In some cases or when using instruments, prominences can be seen;
- Take pictures of a circular glow on the horizon;
- Make simple observations of changes in the environment.
Like any scientific experience, observing eclipses requires adherence to a number of rules that will help make the process one of the most memorable events in life and protect the observer from very real harm to health. First of all, from the possible thermal damage to the retina, the probability of which increases to almost 100% with the unprotected use of optical devices.
Hence the main rule of sun observation: be sure to use eye protection. This can be done with special light filters for telescopes and binoculars, chameleon masks for welding. For the most extreme cases, plain smoked glass is suitable.
What a solar eclipse looks like - watch the video:
It is relatively safe to observe only a short period, only a few minutes, while the total eclipse lasts. Take special care in the initial and final phases, when the brightness of the solar disk is close to maximum. It is recommended to take breaks from observation.
