| Discoveries made thanks to solar eclipses:
Total solar eclipses allow us to view the corona and solar neighborhood which is extremely difficult under normal conditions.
During a total solar eclipse in India on August 18, 1868, French scientist Pierre Janssen, for the first time, studied the chromosphere of the Sun and obtained a spectrum of a new chemical element (however, as it was found later-on, is that this spectrum can be obtained without waiting for a solar eclipse and this was shown by English astronomer Norman Lokyer two months after). The element was named in the honor of the Sun - Helium.
The comet flying past the sun was observed by the observers in Egypt during a solar eclipse on May 17, 1882. It received the name of the Eclipse Comet though it has one more name - Comet Tewfik (in the honor of Khedive of Egypt at that time). The comet belonged to circumsolar comets from the Kreutz family.
Since 1996 astronomers had an opportunity to constantly study the neighborhood of our stars thanks to the satellite SOHO (Solar and Heliospheric Observatory).
Solar eclipses occur more often than the lunar eclipses. Probably, it is paradoxical, after all, apparently, the lunar umbra is much less than the Earth and can obscure only a small portion of the surface of the Earth from the Sun. At the same time, Earth’s umbra is capable of obscuring the Moon entirely. Nevertheless, two solar eclipses occur every year at a minimum while lunar eclipses may not even occur. The maximum number of eclipses in a year is 7. Of 7 eclipses, 4 would be solar eclipses.
On the celestial sphere, the diameter of the Sun and Moon almost match and which could be the reason for the occurrence of solar eclipses. They occur in New Moons, during which the Moon is nearer to nodes of its orbit. But since the lunar orbit is far from being a circle with respect to shape and ascending and descending nodes of orbit move along eclipticly (the lunar orbit changes the orientation in space), the lunar disc can be more, or less than the solar disc during favorable moments for the occurrence of eclipses. In the first case a total eclipse occurs, the duration of which depends on the angular size of the Moon (the more angular size the longer the eclipse would be, up to 7.5 min). In the second case - a total eclipse is instant an annular eclipse occurs in the third case: a radiant ring of solar surface, uncovered by the moon is visible around the dark disc of the moon. Such an eclipse can last up to 12 min.
The second important condition is the mutual positioning of the luminaries in the sky participating in the eclipse. The lunar umbra can be visible or cannot be visible from Earth as in the case when only the penumbra is visible from earth, and only then a partial (incomplete) solar eclipse will be observed. If the lunar eclipse is visible at once on the entire night side of the Earth where the Moon is visible, then total solar eclipses can be observed only in a narrow band of 40-100 (to 270) km in breadth. Vast areas are found on either side of this zone, where it is possible to view the partial eclipse. The small circular dark spot of lunar umbra passes along the earth, which is hardly capable of covering a big city. Therefore, though solar eclipses occur much more often than lunar eclipses, the total solar eclipse can be observed every 200-300 yrs on an average at the same place on Earth. It is quite possible for every person to view a total lunar eclipse several times in life. Certainly, here we mean about a person, who is settled, almost not migrating from the city or settlement. If, someone due to some means has to relocate every year other areas, then this person can observe all the phenomena in the sky only if they are visible from Earth. However, some are already flying into space for a walk. If it is already known to you that the next eclipse would occur some several hundred kilometers from your home, then try to travel this distance. In case of good weather, you will not regret the distance traveled.
|
This Wednesday, people in Asian countries saw a total eclipse of the Sun, lasting for over 6 minutes - the longest solar eclipse this century. The most spectacular view was from China and India, where millions and millions of people gathered on rooftops to see the moon cover the sun in the morning.
