Solar Eclipse On Dec 4: Why A Solar Eclipse Always Occurs 2 Weeks Before Or After A Lunar Eclipse

Solar Eclipse 2021: Eclipses always come in pairs — a solar eclipse occurs around two weeks before or after a lunar eclipse, and vice versa.

Solar eclipse in a cloudy sky. (File Photo/ Getty Images)

New Delhi: After the year’s last lunar eclipse on November 19, which was also the longest in the last around 580 years, it’s time for the last solar eclipse of 2021.

A total solar eclipse will occur on December 4.

Eclipses always come in pairs — a solar eclipse usually occurs around two weeks before or after a lunar eclipse.

A total solar eclipse takes place when the New Moon (when the Sun and Earth are on its opposite sides) comes between the Sun and Earth, and casts the darkest part of its shadow — the umbra — on Earth. 

Only those regions of the world can see a total solar eclipse that are located in the path of the Moon's umbra.

Why Solar And Lunar Eclipses Come In Pairs

There are at least four eclipses every year — two lunar and two solar. And usually two or three eclipses — at least one of them solar — occur during every eclipse season, which is a period that lasts around 34 to 35 days. The order depends on how an eclipse season coincides with the lunar month, according to timeanddate.com.

A lunar month, when the Moon charts its course through all the phases from one New Moon to the next, lasts 29.5 days on an average — five days less than the period of an eclipse season. This is why each eclipse season has at least one New Moon, which causes a solar eclipse, and at least one Full Moon, which results in a lunar eclipse.

This explains why a solar eclipse always precedes or follows a lunar eclipse, and vice versa, by approximately two weeks.

Who Can See December 4 Solar Eclipse?

The December 4 solar eclipse will sweep across Antarctica — the only place where the total phase of the eclipse will be seen. 

A partial solar eclipse can be seen in southern parts of Australia, New Zealand, Africa, and South America, and the Pacific, Atlantic, and the Indian Ocean. 

The solar eclipse will not be visible in India. However, one can see the eclipse via a live webcam — from 10:59 am to 3:07 pm IST, according to timeanddate.com.