There are 2 Kalpas in Brahma's full day of 24 hours not 1
1 kalpa for his 12 hour day
1 kalpa for his 12 hour night
A Catur yuga, Dvipa yuga and Maha yuga - ''A cycle of 4 Yugas''.
The Catur-yuga is also known as Divya-yuga or Maha-yuga and is made up of the four yugas -
''Satya- yuga, Treta-yuga, Dvapara-yuga, Kali-yuga''.
What time is it now in Brahma's day?
Lord Caitanya Mahaprabhu and Lord Krishna come in the 28th Catur-yuga, Divya-yuga or Maha-yuga tn the 7th Vaivasvata Manu (current) Vamanajust "once" in Brahma's 24 hour day
We have already passed through 6 Manvantara's in Brahma's 12 hour day already that each have 71 Maha-yugas in them
So presently we are in the 460th Maha-yuga in Brahma's 12 hour day out of 1000 making it 11.40 am in Brahma's daytime
The Manvantara's are created by a particular Manu who are all created by Brahma
Manvantara or Manuvantara or "Manvanter", or age of a Manu, the Vedic progenitor of humanity, is an astronomical period of time measurement.
Manvantara is a Sanskrit word, a compound of manu and antara, manu-antara or manvantara, literally meaning the duration of a Manu, or his life span.
Each Manvantara is created and ruled by a specific Manu, who in turn is created by Brahma the Creator himself in this single Material Universe called Bhu-Mandala that is deep within our single enormous Brahmanda Egg shaped greater Universe that comes from the pores of Maha Vishnu's Body with billions of other Brahmanda egg shaped Universes .
Brahma creates the this single Material world called Bhu-Mandala however, all the billions of other Brahmanda's also have a similar Bhu-Mandala inner Universe and all have their own individual Brahmas.
There are billions of Brahma's ours has four heads others have 10 or 100 or 1000 or even 10,000 even 10 million! All depending on the size of their material Universe.
Also our Brahmanda that is over 44 quadrillion 444 Trillion miles 444 billion miles in diameter and inner Bhu-Mandala 4 billion sized very small Universe is very small compared to other Brahmandas and their inner Bhu-Mandala similar Universe.
Within our Bhu-Mandala Universe each Manvantara lasts the lifetime of a Manu, upon whose death, Brahma creates another Manu to continue the cycle of Creation or Shristi, Krishna's expansion Lord Vishnu on his part manifests a new Avatar.
Also a new Indra and Saptarishis are appointed.
Fourteen Manus and their respective Manvantaras constitute one Kalpa, Aeon, or a ‘Day of Brahma’, according to the Vedic Time Cycles and also the Vedic timeline.
Thereafter, at the end of each Kalpa, there is a period - same as Kalpa - of dissolution or Pralaya, wherein the world (earth and all life forms, but not the entire universe itself) is destroyed and lies in a state of rest, which is called the, ‘Night of Brahma’.
After that the creator of this single Bhu-Mandala Universe, Brahma starts his cycle of creation all over again, in an endless cycle of creation followed by absorption (annihilation) for which Shiva, Vedic demigod of Absorption and annihilation of this Universe, and also renewal, is invoked towards the end of each such cycle.
Duration of a Manvantara
The actual duration of a Manvantara, according to the Vishnu Purana is seventy one times the number of years contained in the four Yugas, with some additional years, adding up to 852,000 divine years, or 306,720,000 human years.
Seven Rishis, certain (secondary) divinities, Indra, Manu, the king and his sons, are created and perish in one interval (called a Manvantara) equal to seventy-one times the number of years contained in the four Yugas, with some additional years.
This is the duration of the Manu, the (attendant) divinities, and the rest, which is equal to 852,000 divine years, or to 306,720,000 years of mortals, independent of the additional period.
Fourteen times this period constitutes a Bráhma day, that is, a day of Brahmá; the term (Bráhma) being the derivative form. The Brahma life span is 100 Brahma varshas. The following table will illustrate clearly the link to our years and Brahma years.
Sub-divisions
1 human year (in Hindu calendar) = 1 Deva Ahoratra for God (1 day and 1 night)
360 Deva Ahoratras = 1 Deva Vatsara
12,000 Deva Vatsara = 1 Chaturyuga
(12,000 Deva Vatsaras are defined as, 4,800 Deva Vatsaras of satya yuga, 3,600 Deva Vatsaras of Treta Yuga, 2,400 Deva Vatsaras of Dvapara Yuga and 1,200 Deva Vatsaras of Kali Yuga (which is 1,200 * 360 = 432,000 human years); summing up to 12000)
71 Chaturyugas = 1 Manvantaram (1 life span of Manu)
14 Manvantaras = 1 kalpa (1 day of Brahma)
2 Kalpas = 1 day and 1 night 24 hour period + 1 Brahma ratra
360 days of Brahma = 1 Brahma varsha
Comparison to the Age of the Universe from Modern Astronomy
Modern scientific astronomy estimates the Age of the Universe as around 13 Billion years (13 * 109 years).
Conversion of 1 day-night of Brahma into human years yields 8.58816 * 109 years (derived as 2 kalpas * 14 Manvantaras * 71 Chaturyugas * 12,000 Deva vatsaras * 360 human years).
According to Vedas, there are 504 000 Manus manifested during the lifetime of one Brahmā (311,040,000,000,000 human Earthly years), 5,040 Manus in one year of Brahma, and 420 Manus in one month of Brahma.
Manus of the Śveta Vārāha Kalpa
Manvantara № Name of Manu for manvantara:
Manvantara-avatara name:
01 Svayambhuva Manu Yajna
02 Svarocisha Manu Vibhu
03 Uttama Manu Satyasena
04 Tapasa Manu Hari
05 Raivata Manu Vaikuntha
06 Cakshusha Manu Ajita
07 Vaivasvata Manu (current) Vamana
08 Savarni Manu Sarvabhauma
09 Daksha-savarni Manu Rishabha
10 Brahma-savarni Manu Vishvaksena
11 Dharma-savarni Manu Dharmasetu
12 Rudra-savarni Manu Sudama
13 Deva-savarni Manu Yogesvara
14 Indra-savarni Manu Brihadbhanu
First Manvantara - the interval of Swayambhu Manu
Saptarshis (सप्तर्षि): Marichi, Atri, Angiras, Pulaha, Kratu, Pulastya, and Vashishtha.
Svayambhuve—in the Svayambhuva-manvantara; yajna—the avatara named Yajna:
In the Svayambhuva-manvantara, the Avatar is named Yajna.
The first Manu was Svayambhuva Manu. His two daughters, namely Akuti and Devahuti, gave birth to two sons, named Yajna and Kapila respectively.
Svayambhuva Manu, along with his wife, Satarupa, went into the forest to practice austerities on the bank of the River Sunanda.
At some point in time, Rakshasas and asuras attacked them, but Yajna, accompanied by his sons the Yamas and the demigods, killed them.
Then Yajna personally took the post of Indra, the King of the heavenly planets.
Second Manvantara - the interval of Swarochisha Manu
Urjastambha, Agni, Prańa, Danti, Rishabha, Nischara, and Charvarivan. In the Svarocisha-manvantara, avatara is named Vibhu.
The second Manu, whose name was Svarocisha, was the son of Agni, and His sons were headed by Dyumat, Sushena and Rochishmat.
In the age of this Manu, Rochana became Indra, the ruler of the heavenly planets, and there were many demigods, headed by Tushita.
There were also many saintly persons, such as Urjastambha. Among them was Vedasira, whose wife, Tushita, gave birth to Vibhu.
Vibhu instructed eighty-eight thousand dridha-vratas, or saintly persons, on self-control and austerity.
Third Manvantara - the interval of Uttama Manu.
Sons of Vashista: Kaukundihi, Kurundi, Dalaya, Śankha, Praváhita, Mita, and Sammita. In the Uttama-manvantara, He (avatara) is named Satyasena.
Uttama, the son of Priyavrata, was the third Manu.
Among his sons were Pavana, Srinjaya and Yajnahotra. During the reign of this Manu, the sons of Vashista, headed by Pramada, became the seven saintly persons.
The Satyas, Devasrutas and Bhadras became the demigods, and Sushanti became Indra. From the womb of Sunrita, the wife of Dharma, the Lord appeared as Satyasena, and He killed all the Yakshas and Rakshasas who were fighting with Satyajit.
Fourth Manvantara - the interval of Tapasa/Tamasa Manu
Jyotirdhama, Prithu, Kavya, Chaitra, Agni, Vanaka, and Pivara.
In the Tapasa-manvantara, He (Vishnu) is named Hari.
He is named Tapasa because he was born during Tapassu (deep meditation)
Tapasa/Tamasa, the brother of the third Manu, was the fourth Manu, and he had ten sons, including Prithu, Khyati, Nara and Ketu.
During his reign, the Satyakas, Haris, Viras and others were demigods, the seven great saints were headed by Jyotirdhama, and Trisikha became Indra.
Harimedha begot a son named Hari by his wife Harini. Hari saved the devotee Gajendra. This incident known as gajendra-mokshana.
Fifth Manvantara - the interval of Raivata Manu
Hirannyaroma, Vedasrí, Urddhabahu, Vedabahu, Sudhaman, Parjanya, and Mahámuni.
In the Raivata-manvantara, the avatara is named Vaikuntha.
Vaikuntha came as Raivata Manu, the twin brother of Tamasa. His sons were headed by Arjuna, Bali and Vindhya.
Among the demigods were the Bhutarayas, and among the seven brahmanas who occupied the seven planets were Hiranyaroma, Vedasira and Urdhvabahu.
Sixth Manvantara - the interval of Chakshusha Manu
Sumedhas, Virajas, Havishmat, Uttama, Madhu, Abhináman, and Sahishnnu. In the Chakshusha-manvantara, avatara is named Ajita.
Ajita came as Chakshsusa Manu, the son of the demigod Chakshu. He had many sons, headed by Puru, Purusa and Sudyumna.
During the reign of Chakshusa Manu, the King of heaven was known as Mantradruma. Among the demigods were the Apyas, and among the great sages were Havisman and Viraka.
The present, seventh Manvantara - the interval of Vaivasvata Manu
Kashyapa, Atri, Vashista, Vishvamitra, Gautama, Jamadagni, Bharadvaja.[9] In the Vaivasvata-manvantara, He (Avatara) is named Vamana
The seventh Manu, who is the son of Vivasvan, is known as Sraddhadeva
.
He has ten sons, named Iksvaku, Nabhaga, Dhrsta, Saryati, Narisyanta, Dista, Tarusa, Prsadhra and Vasuman.
In this manvantara, or reign of Manu, among the demigods are the Adityas, Vasus, Rudras, Visvedevas, Maruts, Asvini-kumaras and Rbhus.
The king of heaven, Indra, is known as Purandara, and the seven sages are known as Kashyap, Atri, Vashista, Vishwamitra, Gautama, Jamadagni and Bharadwaj.
During this period of Manu, Vishnu appears from the womb of Aditi in his incarnation as the son of Kashyap.
Eighth (Future) - Savarni Manu
Diptimat, Galava, Parasurama, Kripa, Drauni or Ashwatthama, Vyasa, and Rishyasringa.
In the Savarnya-manvantara, He (avatara) is named Sarvabhauma.
In the period of the eighth Manu, the Manu is Surya Savarnika Manu. His sons are headed by Nirmoka, and among the demigods are the Sutapas.
Bali, the son of Virochana, is Indra, and Galava and Parasurama are among the seven sages. In this age of Manu, the incarnation of the Supreme Personality of Godhead appears as Sarvabhauma, the son of Devaguhya and Sarasvati.
Nineth - Daksa Savarni Manu
Savana, Dyutimat, Bhavya, Vasu, Medhatithi, Jyotishmán, and Satya. In the Daksha-savarnya-manvantara, He (avatara) is named Rishabha.
In the period of the ninth Manu, the Manu is Daksha-savarni. His sons are headed by Bhutaketu, and among the demigods are the Maricigarbhas.
Adbhuta is Indra, and among the seven sages is Dyutiman. In this period of Manu, the incarnation Rishabha is born of Ayushman and Ambudhara.
Tenth - Brahma Savarni Manu
Havishmán, Sukriti, Satya, Apámmúrtti, Nábhága, Apratimaujas, and Satyaket. In the Brahma-savarnya-manvantara, the avatara is named Vishvaksena.
In the period of the tenth Manu, the Manu is Brahma-savarni.
Among his sons is Bhurishena, and the seven sages are Havishman and others. Among the demigods are the Suvasanas, and Sambhu is Indra.
The incarnation in this period of Manu is Vishvaksena, who is a friend of Sambhu and who is born from the womb of Vishuci in the house of a brahmana named Visvasrashta.
Eleventh - Dharma Savarni Manu
Niśchara, Agnitejas, Vapushmán, Vishńu, Áruni, Havishmán, and Anagha. In the Dharma-savarnya, He (avatara) is named Dharmasetu.
In the period of the eleventh Manu, the Manu is Dharma-savarni, who has ten sons, headed by Satyadharma.
Among the demigods are the Vihangamas, Indra is known as Vaidhrita, and the seven sages are Aruna and others. In this manvantara, the incarnation is Dharmasetu, who is born of Vaidhrita and Aryaka.
Twelfth - Rudra Savarni Manu
Tapaswí, Sutapas, Tapomúrtti, Taporati, Tapodhriti, Tapodyuti, and Tapodhan. In the Rudra-savarnya He (avatara) is named Sudhama.
In the period of the twelfth Manu, the Manu is Rudra-savarni, whose sons are headed by Devavan. The demigods are the Haritas and others, Indra is Ritadhama, and the seven sages are Tapomurti and others.
The incarnation in this manvantara is Sudhama, or Svadhama, who is born from the womb of Sunrita. His father's name is Satyasaha.
Thirteenth - Raucya or Deva Savarni Manu
Nirmoha, Tatwadersín, Nishprakampa, Nirutsuka, Dhritimat, Avyaya, and Sutapas. In the Deva-savarnya, He (avatara) is named Yogesvara.
In the period of the thirteenth Manu, the Manu is Deva-savarni. Among his sons is Chitrasena, the demigods are the Sukarmas and others, Indra is Divaspati, and Nirmoka is among the sages.
The manvantara-avatara is Yogeshwara, who is born of Devahotra and Brihati.
Fourteenth - Indra Savarni Manu
Agnibáhu, Śuchi, Śhukra, Magadhá, Gridhra, Yukta, and Ajita. In the Indra-savarnya-manvantara, the avatara is named Brihadbhanu.
In the period of the fourteenth Manu, the Manu is Indra-savarni. Among his sons are Uru and Gambhira, the demigods are the Pavitras and others, Indra is Suci, and among the sages are Agni and Bahu.
However, it is said both Lord Krishna in His original form and Lord Caitanya only come ''once'' in a day of Brahma, that ''day'' really means a ''day and night 24 hour period of Brahma'' that together over 24 hours takes 8 billion 640 million human years.
Then night-time comes which is also 4 billion 320 million human years long.
At night while Brahma sleeps and creates no Chatur-yuga or Maha-yugas, our Universe is partially annihilated.
When the next day-time arrives at sunrise the cycle repeats itself for every day and night of Brahma's life
We are in the 28th Catur-yugas or Maha-yuga in the ''Vaivasvata Manu'' (current) that has 71 Maha-yugas in it.
71 Chatur-yugas = 1 Manvantara (1 life span of Manu)
We are in the 460th Maha-yuga also known as a Catur-yuga which is the 28th Maha-yuga in the 7th Manuvantara named Vaivasvata which means we have passed through 6 Manvantara's already in Brahma's day-time hours making it about 11.40 am in Brahma's daytime.
There are no Maha-yugas in Brahma's night.
At night while Brahma sleeps and creates NO Chatur-yuga or Maha-yugas, our Universe is partially annihilated.
When the next day-time arrives at sunrise the cycle repeats itself for every ''day and night'' of Brahma's life
Source of knowledge is the Srimad Bhagavatam also known as the Bhagavat Purnana by Srila AC Bhaktivedanta Swami Prabhupada