Hindu units of time

[7] By contrast, persons born between March 21 - April 19 would have the sun sign of Aries per tropical calculations.

[17] This system was integral to ancient cultures for tracking time, planning festivals, and guiding agricultural practices.

[20] The following section explains these units and their approximate durations, offering insight into how time is organized in relation to the tropical year:[21][a] The table below contains calculations of cosmic Hindu units of time as experienced by different entities, namely humans, Pitris (forefathers), Devas (gods), Manu (progenitor of humanity), and Brahma (creator god).

According to Puranic sources,[e] Krishna's departure marks the end of the human age of Dvapara-yuga and the start of Kali-yuga, which is dated to midnight on 17/18 February 3102 BCE of the proleptic Julian calendar.

Satya-yuga), Tretā-yuga, Dvāpara-yuga and Kali-yuga—each with a 25% decline in dharmic practices and length, giving proportions (caraṇas; pronounced charanas) of 4:3:2:1 (e.g. Satya: 100% start; Kali: 25% start, 0% end), indicating a de-evolution in spiritual consciousness and an evolution in material consciousness.

Preceding the first and following each manvantara is a sandhyā (connection period), each lasting the duration of Satya-yuga (1.728 million years).

His 100-year life (311.04 trillion years) is called a mahā-kalpa, which is followed by a mahā-pralaya (full dissolution) of equal length, where the bases of the universe, prakriti, is manifest at the start and unmanifest at the end of a maha-kalpa.

(14) Persons well-read in mathematical science say that a year is made up of two solar motions, viz, the northern and the southern.

That division consists in this the light half of the month is their day which is for work, and the dark fortnight is their night for sleep.

Laws of Manu; 1.64–80) describes units of time from a twinkling of the eye (nimesha) up to the days (kalpa) and nights (pralaya) of Brahma.

[45][46][47] निमेषा दश चाष्टौ च काष्ठा त्रिंशत् तु ताः कला । त्रिंशत् कला मुहूर्तः स्यादहोरात्रं तु तावतः ॥ ६४ ॥ nimeṣā daśa cāṣṭau ca kāṣṭhā triṃśat tu tāḥ kalā । triṃśat kalā muhūrtaḥ syādahorātraṃ tu tāvataḥ ॥ 64 ॥ (64) Eighteen nimeshas (twinklings of the eye, are one kashtha), thirty kashthas one kala, thirty kalas one muhurta, and as many (muhurtas) one day and night.

अहोरात्रे विभजते सूर्यो मानुषदैविके । रात्रिः स्वप्नाय भूतानां चेष्टायै कर्मणामहः ॥ ६५ ॥ ahorātre vibhajate sūryo mānuṣadaivike । rātriḥ svapnāya bhūtānāṃ ceṣṭāyai karmaṇāmahaḥ ॥ 65 ॥ (65) The sun divides days and nights, both human and divine, the night (being intended) for the repose of created beings and the day for exertion.

पित्र्ये रात्र्यहनी मासः प्रविभागस्तु पक्षयोः । कर्मचेष्टास्वहः कृष्णः शुक्लः स्वप्नाय शर्वरी ॥ ६६ ॥ pitrye rātryahanī māsaḥ pravibhāgastu pakṣayoḥ । karmaceṣṭāsvahaḥ kṛṣṇaḥ śuklaḥ svapnāya śarvarī ॥ 66 ॥ (66) A month is a day and night of the manes, but the division is according to fortnights.

दैवे रात्र्यहनी वर्षं प्रविभागस्तयोः पुनः । अहस्तत्रोदगयनं रात्रिः स्याद् दक्षिणायनम् ॥ ६७ ॥ daive rātryahanī varṣaṃ pravibhāgastayoḥ punaḥ । ahastatrodagayanaṃ rātriḥ syād dakṣiṇāyanam ॥ 67 ॥ (67) A year is a day and a night of the gods; their division is (as follows): the half year during which the sun progresses to the north will be the day, that during which it goes southwards the night.

चत्वार्याहुः सहस्राणि वर्षाणां तत् कृतं युगम् । तस्य तावत्शती सन्ध्या सन्ध्यांशश्च तथाविधः ॥ ६९ ॥ catvāryāhuḥ sahasrāṇi varṣāṇāṃ tat kṛtaṃ yugam । tasya tāvatśatī sandhyā sandhyāṃśaśca tathāvidhaḥ ॥ 69 ॥ (69) They declare that the Krita age (consists of) four thousand years (of the gods); the twilight preceding it consists of as many hundreds, and the twilight following it of the same number.

दैविकानां युगानां तु सहस्रं परिसङ्ख्यया । ब्राह्ममेकमहर्ज्ञेयं तावतीं रात्रिमेव च ॥ ७२ ॥ daivikānāṃ yugānāṃ tu sahasraṃ parisaṅkhyayā । brāhmamekamaharjñeyaṃ tāvatīṃ rātrimeva ca ॥ 72 ॥ (72) But know that the sum of one thousand ages of the gods (makes) one day of Brahman [(Brahma)], and that his night has the same length.

तद् वै युगसहस्रान्तं ब्राह्मं पुण्यमहर्विदुः । रात्रिं च तावतीमेव तेऽहोरात्रविदो जनाः ॥ ७३ ॥ tad vai yugasahasrāntaṃ brāhmaṃ puṇyamaharviduḥ । rātriṃ ca tāvatīmeva te'horātravido janāḥ ॥ 73 ॥ (73) Those (only, who) know that the holy day of Brahman [(Brahma)], indeed, ends after (the completion of) one thousand ages (of the gods) and that his night lasts as long, (are really) men acquainted with (the length of) days and nights.

यद् प्राग् द्वादशसाहस्रमुदितं दैविकं युगम् । तदेकसप्ततिगुणं मन्वन्तरमिहोच्यते ॥ ७९ ॥ yad prāg dvādaśasāhasramuditaṃ daivikaṃ yugam । tadekasaptatiguṇaṃ manvantaramihocyate ॥ 79 ॥ (79) The before-mentioned age of the gods, (or) twelve thousand (of their years), being multiplied by seventy-one, (constitutes what) is here named the period of a Manu (Manvantara).

According to Patrick Olivelle, most scholars take the table of contents (1.111–118) to be an addition, but for him the account of time and cosmology (1.61–86) to the aforementioned (1.118) are out of place redactions.

Kulluka and Olivelle reject Medhatithi's interpretation based on 1.79 mentioning 12,000 without a qualifier ("etat" or "this") and must be assumed as years.

[49] The Surya Siddhanta (1.10–21) describes units of time from a respiration (prana)[50] up to the 100-year lifespan of Brahma (maha-kalpa).

surāsurāṇām anyonyam ahorātraṃ viparyayāt । tatṣaṣṭiḥ ṣaḍguṇā divyaṃ varṣam āsuram eva ca ॥ 14 ॥ (14) The day and night of the gods and of the demons are mutually opposed to one another.

taddvādaśasahasrāṇi caturyugam udāhṛtam । sūryābdasaṃkhyayā dvitrisāgarair ayutāhataiḥ ॥ 15 ॥ (15) Twelve thousand of these divine years are denominated a Quadruple Age (caturyuga); of ten thousand times four hundred and thirty-two [4,320,000] solar years saṃdhyāsaṃdhyāṃśasahitaṃ vijñeyaṃ tac caturyugam । kṛtādīnāṃ vyavastheyaṃ dharmapādavyavasthayā ॥ 16 ॥ (16) Is composed that Quadruple Age, with its dawn and twilight.

sasaṃdhayas te manavaḥ kalpe jñeyāś caturdaśa । kṛtapramāṇaḥ kalpādau saṃdhiḥ pañcadaśaḥ smṛtaḥ ॥ 19 ॥ (19) In an Æon (kalpa) are reckoned fourteen such Patriarchs (manu) with their respective twilights; at the commencement of the Æon is a fifteenth dawn, having the length of a Golden Age.

ittham yugasahasreṇa bhūtasaṃhārakārakaḥ । kalpo brāhmam ahaḥ proktaṃ śarvarī tasya tāvatī ॥ 20 ॥ (20) The Æon, thus composed of a thousand Ages, and which brings about the destruction of all that exists, is styled a day of Brahma; his night is of the same length.