A Brahma has a lifespan of a hundred years.
‘A’ Brahma because there are millions and millions of Brahmas.
They appear and disappear like bubbles in the causal ocean.
Each Brahma creates his own universe.
Brahma of our ‘little’ universe is now 50 years old.
We are in the first day of his fifty-first year.
Brahma’s one year is made up of 360 days.
During his day-time Brahma is awake.
He wakes up at his dawn and creates the universe.
At his dusk, Rudra eliminates the universe, dissolving it back into the causal ocean.
Then Brahma sleeps during his night-time.
At that time, there is no universe.
Brahma’s day-time is 4.32 billion human years.
This is called a Kalpa.
His night-time is also 4.32 billion human years.
In this way, in his lifespan, Brahma creates 36,000 universes.
His total lifespan is 311.04 trillion human years.
At the end of each of his days, each one of them disappears.
A Kalpa is divided into 14 Manvantaras.
Manvantaras are named after their rulers, Manus.
We are now in the seventh Manvantara.
It is called Vaivaswata Manvantara.
Its ruler is Vaivaswata Manu.
There are 71 yuga-cycles in each Manvantara.
One sequence of Satya yuga - Treta yuga - Dwapara yuga - Kali yuga is called a yuga-cycle or Mahayuga or Chaturyuga.
They repeat 71 times in a Manvantara.
14 Manvantaras add up to 4.29408 billion human years.
Then, there are 15 Manvantara Sandhyas.
One each at the beginning and end of the Kalpa and one each in between the Manvantaras.
The 15 Sandhyas add up to 2.592 crore human years.
Thus, all put together the duration of the Kalpa is 4.32 billion human years.
Each yuga-cycle is 4,320,000 human years.
Out of this, Satya yuga is 17,28,000 human years.
Treta yuga is 12,96,000 human years.
Dwapara yuga is 8,64,000 human years.
And Kali yuga is 4,32,000 human years.
Each Yuga also has its own Sandhyas.
For example, Kali yuga of 4,32,000 years is made up of Kali yuga proper of 3,60,000 years and Sandhyas at its beginning and end each with a duration of 36,000 years.
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