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Introduction to Solar eclipse

I think all of you watched the Solar eclipse of 26th December 2019. Let us try to understand a bit of the basics of Solar eclipse

Sun-Earth –Moon positions and distances are so balanced that we get TWO types of solar eclipses WHEN THEY ARE INLINE. (Many partial eclipses will occur when they are not inline. That is not discussed here).

Earth revolves around the Sun in an elliptical orbit. Hence it will be nearest to the Sun on January 3rd of every year. This position of the Earth’s orbit is called aphelion. Similarly, it will be at the farthest distance from the Sun on July 4th of every year, this position is called as perihelion. (these positions will also get advanced through 1 day for every 70 years. Also, due to Earth- moon system, this may vary about 2 days within 70 years and called as Milankovitch cycles. Anyway, do not bother if you cannot understand this).  When it is nearest , the Sun-Earth distance will be approximately 147000000 km and when it is farthest, it will be approximately 152000000km.

Moon also revolves around the Earth in an elliptical orbit. Hence it will be nearest to the Earth and farthest to the earth almost every month. When it is nearest , the Sun-Earth distance will be approximately 362600 km and when it is farthest, it will be approximately 405400km.

Note: Moon need not be always closest to Earth when Earth is closest to Sun and so on. These are very rare chances may happen once in thousands of years.

Explanation

  • Figures are not to scale. These are constructed by the Author for illustration purpose only.
Figure-1. Representing Annular solar eclipse of December 2019.

Figure 1 Shows the position of Sun-Earth-Moon such that SIZE OF THE SUN appears to be bigger than that of moon,  to an observer from a point  on earth. In such cases, Annular eclipse will occur, when the three are inline. That was the case of Solar eclipse 2019 December .

Figure-2. Representing Total solar eclipse due in December 2020.

Figure 2 Shows the position of Sun-Earth-Moon such that SIZE OF THE SUN appears to be Smaller than or equal to that of the moon, to an observer from a point  on earth. In such cases, total solar eclipse will occur, when the three are inline. That will occur on 14th December 2020.

So, you can enjoy 2020 Solar eclipse in a better way.

You can also read : Understanding the earthquake