The lunar eclipse is observed when the satellite of Earth enters a shadow which our planet casts from the Sun, that is Earth in that case is between a star and the Moon. At the same time the Moon can get only partially to a shadow, and can be covered completely with it therefore distinguish partial and full eclipses. Every year it is possible to observe two and more lunar eclipses with various phases.
1. When the Sun shines to Earth, on the other side of the planet the cone of a dense shadow surrounded with a penumbra is formed. If the Moon at this moment partially or completely is included into this cone, from the surface of the planet from that party where our satellite is visible, the lunar eclipse will be observed. It looks not so impressively as solar, but it is simpler to observe it. Brightly lit Moon slowly begins to become covered by a shadow, but remains visible thanks to the sunshine disseminated in the atmosphere of Earth which light its surface with reddish light. The eclipse can last more than one and a half hours, the Moon gradually comes out of the shadow and again is lit with the Sun. If the eclipse partial, then only a part of the satellite becomes dark. In certain cases the Moon is not included into a full shadow, and remains in a penumbra – such eclipse is called penumbral.
2. On average every year there are 2-3 lunar eclipses, but in separate years this phenomenon is not observed at all, and in other years it is possible to see 4 and even 5 lunar eclipses. The quantity of eclipses changes from year to year with a certain frequency which repeats each 18 years and 11 days. This interval is called saros or the drakonichesky period. During this term there are 29 lunar eclipses – 12 less, than solar. Two thirds of all eclipses make partial, one third – full.
3. In spite of the fact that lunar eclipses statistically there are less solar, the thicket because the first are well visible from all half of Earth which is not lit at present with a star can observe them, and the second are looked through only in rather small territory with a diameter about 300 kilometers. Therefore in the different ends of the planet the frequency of these astronomical phenomena can be various. Solar eclipses repeat in the same place approximately time in 300 years therefore if the person lives in one area, for the life he can see a set of lunar eclipses, but any solar.
4. The calendar of lunar eclipses can be found in astronomical reference books and the specialized websites on the Internet. Knowing in what place and in what time in the history there was an eclipse, it is possible to calculate year, month and day when it repeats, by means of a saros. Besides, the drakonichesky period and descriptions of eclipses allow scientists to date historical events precisely.
5. For 2014 two total lunar eclipses are necessary, in 2015 it will be possible to observe 2 total eclipses too, and in 2016 there will be only penumbral. Till 2020 there will be about 2 eclipses of the Moon in a year, and in 2020 it will be possible to see the whole 4 such phenomena.