Yuga (Devanāgari: युग) in Hindu philosophy is the name of an ‘epoch’ or ‘era’ within a cycle of four ages. These are the Satya Yuga (or Krita Yuga), the Treta Yuga, the Dvapara Yuga and finally the Kali Yuga. According to Hindu cosmology, life in the universe is created, destroyed once every 4.1 to 8.2 billion years, which is one full day (day and night) for Brahma. The lifetime of a Brahma himself may be 311 trillion and 40 Billion years
Each yuga is an age with specific characteristics in which incarnations of Krsna appear. The four yugas make up a cycle called divya-yuga, which lasts 4,320,000 years. One thousand of these yugas equal one day of Brahma, which is called a kalpa. Brahma’s lifespan is 100 years of his time. In each yuga there is a specific process of self-realization (yuga dharma).
1. Satya Yuga 4 x 432000 years
2. Treta Yuga 3 x 432000 years
3. Dvapara yuga 2 x 432000 years
4. Kali Yuga 432000 years
1. SATYA YUGA
(sometimes also called krta-yuga): the golden age lasts 1,728,000 years. The process of self-realization in this yuga is meditation on Visnu. During this yuga the majority of the population is situated in the mode of goodness and the average life span at the beginning of the yuga is 100,000 years.
The ‘Age of Truth’ or the Golden Age. It is the age of purity and justice, when truth and right conduct were natural to all. Swords, spears, and weapons of war had not been invented. Hatred, selfishness, fear, and sorrow were unknown. Fruits and grain sprang from the earth without labor. There was no winter, only a beautiful, endless spring. No man tried to do the duty of another, but attended strictly to his own; hence there was justice, peace, happiness. There was one religion over the whole earth, the religion of Brotherhood. This is also called Krita-yuga or the ‘Age of Perfect Things,’ for krita means finished, perfected, well made, something that cannot be improved.
2. TRETA YUGA
Also called the silver age, lasts 1,296,000 years and the process of self realization is the performance of opulent yajnas(sacrifices). The average life span is 10,000 years and the godly qualities decrease one fourth compared to the Satya yuga. It is during this age that Varna-asrama-dharma is introduced.
The ‘Age of the Three Fires.’ Treta means three, or a group of three. It is the ‘Age of Triads.’ Three parts of good remained, but one part now was evil. Instead of the fires of aspiration burning in the heart, men now began to build fires of wood upon the altars, and make sacrifices there. They thought the gods would overlook injustice if only men made ceremonies and lighted altar fires. Winter came with its chill; men built houses. Quarreling and hatred came in.
3. DVAPARA YUGA
The bronze age, lasts 864,000 years and the process of self realization is the worship of the deities within temples. Godly qualities are reduced to 50% by now and the average life expectancy is only 1000 years.
The ‘Age of the Number Two.’ The word Dvapara is the name for that side of a die or of dice that has two spots. Two is the ancient symbol of matter (as Three is of spirit). In this Age only two parts of goodness were left. Two parts were now wickedness. Nature became unkind (as men thought), too hot, too cold, many storms. Hunger and unhappiness came in. There were many diseases. It was indeed the ‘Age of the Number Two,’ material and unkind.
4. KALI YUGA
The iron age of hypocrisy and quarrel lasts 432,000 years. Lord Krsna appeared in His original, trancendental form right before the beginning of Kali Yuga. The process of self realization is sankirtana, the chanting of the Holy Names of the Lord. God consciousness is reduced to 25% of the population and life expectancy is only 100 years. By now already 5000 years of Kali yuga have passed and it is predicted that by the end of the yuga people will hardly be older than 20 years and their only food will be meat.
The ‘Age of Strife and Discord,’ for this is what kali means. Legend says that Kali (strife) was the son of Krodha (anger) and Hinsa (injury), and the father of Bhaya (fear) and Mrityu (death). It is called the Black Age, and also the Iron Age. War and hatred spread over the whole Earth. One by one the bright gods went away, though from time to time they sent their Messengers to tell people about the Golden Age of the past, and inspire them to work for another Golden Age in the future. Kali-yuga is the age in which we are now living. It began at the death of Krishna. It ended its first 5000 years on February 18, 1898. What is our great work, then? It is to bring the Golden Age back, the Age of Truth, the ‘Age of Perfect Things.’
Average human lifespan
Satya Yuga:- Average human lifespan was 100,000 years.
Treta Yuga: – Average human lifespan was 10,000 years.
Dwapar Yuga: – Average human lifespan was 1000 years.
Kali Yuga: – Average human lifespan will be 100 years, and will decrease gradually.
From Satya Yuga to Kaliyuga there was a gradual decline of dharma, wisdom, knowledge, intellectual capability, life span, emotional and physical strength of man.
By now already 5000 years of Kali yuga have passed. In Bhagwat Puran, Garud Puran and other Hindu texts it is written that at the end of Kali Yuga, the average size of human beings would be around 1 foot, average age would be maximum 12 years. The decline in height and age started after Satya Yuga when average human height was 32 feet and age was lac of years, with wishful death – no illness or ailments in body.We practicaly see in Mahabharata, the age of Bhisma, who lived with fourth generation of Kuruvansh, and many sages who were alive from other yugas. Even in Ramayana we see Rama, passed 14 years of exile in forest easily, which seems unrealistic today. The Characters of Ramayana and Mahabharata had done so many things in their lifespan, which is not possible if they had not lived a longer life.
This article should answer this: How long is a yuga?