The Moon will come in between the Earth and the Sun today, obscuring its light and casting a dark shadow in some regions on Earth. The solar eclipse is scheduled to begin around 9pm Indian Standard Time on Monday (April 8) and cast a dark shadow on path of totality - the narrow band where people will witness the Sun being completely obscured by the Moon, also known as total solar eclipse. Unless people are on that line - the path of totality - they will only see a partial eclipse.
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The total solar eclipse has five phases: Partial, total, totality and maximum, the ending of total eclipse and finally, the Sun comes out as partial eclipse ends too.
How long does the totality last?
Even after so many centuries, the sight of our Sun - a fireball - getting completely eclipsed by the shadow of the Moon gives goosebumps to many enthusiasts. The entire eclipse can last for several hours, but totality can range from a few seconds to 7.5 minutes.
The outer limit has been revealed by NASA. The space agency said that the longest possible duration of a total solar eclipse is seven minutes and 32 seconds.
This difference results from the fact that the Moon's diametre is much smaller than the extension of Earth's shadow at the Moon's distance from Earth, but the Moon can be only a little greater in apparent size than the Sun.
The longest total solar eclipse of the 21st century took place on July 22, 2009, when totality lasted 6 minutes and 39 seconds.
Cycles of eclipse
Such celestial events are fascinating, but they do not occur every month. Why? Encyclopaedia Britannica explains that one basic time period involved in the occurrence of eclipses is the synodic month - the interval between successive new moons, as seen from Earth.
This happens because the Moon's orbital plane is inclined to the ecliptic - the plane of the orbit of Earth around the Sun. The angle between the planes is about five degrees. Due to this, the Moon doesn't block out the Sun on every orbit, and that's why not every new moon results in a solar eclipse.
