Events that shaped human migrations • The last ice age began about 120,000 years ago. Origins of Astronomy • The Last Glacial Maximum, occurred about 18,000 BCE. • Between 15,000 BCE and 5,000 BCE, most of the world's glaciers melted the sea reclaimed former beaches and even valleys. • This movement of the sea inland occurred in several steps. – 13,000 BC Mayank Vahia – 9,000 - 8,000 BCE. 22 mm/year Tata Institute of Fundamental Research – 6,000 BCE. 2 mm/year – From 3000 BC, the rise is 7.5 mm/year. Mumbai 400 005 • Myths of great floods occur in many of the world's cultures.

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End of Ice Age and Human Migration • The last great Ice Age ended around 15,000 AVERAGE years ago and that must have facilitated human SNOW LINE migration.

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1 1,000,000 years in a nutshell!

• Human race (Homo sapiens) first originate in Africa about million years ago. • They remain confined to central and northern Africa for almost 900,000 years! • Due to a mixture of reasons such as: – Sheer tireless desire to explore. – An overflow from population growth. – Inability of the local food sources to support a large human population. – Internal conflicts of personality within the population. – Differences in taste and preferred environment for settlement.

They migrate out of Africa about 100,000 years ago.

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2 Migration and evolution Astronomy • Human race has gone through various stages of development. • By all indications, serious astronomy begins in – Palaeolithic – First appearance of humans to 10,000 BCE. Neanderthal Man & Homo Erectus existed until 30,000 B.C. Stone tools of increasing late Palaeolithic age itself. complexity mark this period. – Mesolithic – 11,000 to 9,000 BCE. Metals are used in this period. – Neolithic – pre-historic period 9,000 – 1,000 BCE. Sophisticated cultures and organised existence mark this age. • Well accepted astronomical markings have • Calolithic (Copper Stone) Age, 5500-3000 BCE. been dated to 15,000 BCE • Bronze Age 3000 -1200 BCE. • Iron Age 1200 BCE - • Silicon age 2000 AD - – Historic period . • We shall show later that stone carvings of much

• THESE PERIODS VARY FROM REGION TO REGION earlier dates also exist.

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Pleiades

Babylonian "map of the world" It Taurus is the earliest extant map. The clay tablet is 12.2 cms tall. The map was composed in Babylonia and is the only Orion Babylonian map drawn on an international scale. It is a Persian Period, (500 BCE) copy of an original dating to late eighth or seventh century BCE.

Origins of Astronomy prehistoric caves at 11 Origins of Astronomy 12 Lascaux in France.

3 SO WHAT IS THE ROLE OF ASTRONOMY? First steps

• Astronomy is the first ‘science’. • Astronomy begins very early in Human life

• Sky obviously gets noticed quickly. • The second thing we notice in the sky is • In a steady landscape, it is the fastest moving thing the Moon (apart from animals and insects!).

• Sun rise and sunset are important for most life on Earth.

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Moon’s path • Moon moves only in a narrow region in the sky. Calculation of tithis • Moon visibly drifts in the night sky. • Tithis are the dates of Lunar Calendar. It is related to the phase of the moon. • It follows a specific path that is marked by a series of stars. Tithi = long. of Moon – Long. of Sun • Moon waxes and wanes with a time period of 29/30 days. • At Full Moon the Moon rises at Sunset and then drifts towards the Sun and after New moon it rises later and later till it rises at Sunset again. • Tithi remains the same until the Moon in increases its distance from the Sun by 12 degrees. The complete revolution of the • Full Moon occurs near of different stars each month. Moon (29.5 days) occupies 30 tithi s for 360 0. • Synodic (Full moon to full moon) and Sidereal (w.r.t. distant stars) periods are different. • Moon does not move at constant velocity so the length of tithis • Since the Sidereal period is 27 days, the sky can be divided into 27 varies. different parts where the Moon spends 1 day. This forms the basis of Nakshatras . • The waning phase (from Full Moon to New Moon) is called Krishna Paksha and the waxing phase (from New Moon to Full • Moon gives us the concept of month, fortnight and week. Moon) is called Shukla Paksha. Bhujle and Vahia, 2006 Origins of Astronomy 15 Origins of Astronomy 16

4 Names of tithis: (starting with Full Moon) Constellations Number Phase Tithi Number Phase Tithi 1 Krishna Pratipada 16 Shukla Pratipada 2 Krishna Dvitiya 17 Shukla Dvitiya • Sky is divided into patterns that we call 3 Krishna Tritiya 18 Shukla Tritiya constellations . 4 Krishna Chaturthi 19 Shukla Chaturthi 5 Krishna Panchami 20 Shukla Panchami 6 Krishna Shashthi 21 Shukla Shashthi • Star patterns on the path of the Moon are called 7 Krishna Saptami 22 Shukla Saptami Lunar Mansions (asterism) or Nakshatras . 8 Krishna Ashtami 23 Shukla Ashtami 9 Krishna Navami 24 Shukla Navami 10 Krishna Dasami 25 Shukla Dasami 11 Krishna Ekadasi 26 Shukla Ekadasi • Sun mostly follows this path. 12 Krishna Dwadasi 27 Shukla Dwadasi 13 Krishna Trayodasi 28 Shukla Trayodasi 14 Krishna Chaturdashi 29 Shukla Chaturdashi • The constellations on the path of the Sun are 15 Krishna Amavasya 30 Shukla Purnima called Rashis or Zodiacal Signs.

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Importance of Constellations

• Constellations help remember the sky

• They are small and easily recognisable.

• That they permit a universal definition of directions independent of geography

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5 Circumpolar constellations Path of the Sun • Sun mostly follows the path of the Moon. The difference is more • Not all constellations rise and set. important than the similarity. • Since the Sun is very bright, Sun’s path is inferred by looking at the constellations just before Sunrise or just after Sunset. • Pole star never sets and constellations close to it also do not set. • The path of the Sun is divided into 12 Rashis or Zodiacal signs. Roughly 2.25 Nakshatras fit into a rashi.

• The Sun returns to the same Rashi when the Moon completes • This gives a fixed (north) direction and 12 revolutions. circumpolar constellations permit determination • 12 months therefore make one year (approximately) of exact (geographic) north .

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6 The East

• The Sun does not rise in the exact (global) east, i.e. it does not rise exactly at the point between north and south.

• It rises in the eastern direction and sets in the western direction

• But within that, the sun rises exactly in the (local) east i.e. the line joining sunrise point and sunset point is perpendicular to the line joining the observer to the north.

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Sunrise and Sunset

• The Sun rise point drifts North of East to South of East

• On Equinox (Spring or Autumn), the Sun rises exactly in the (global) East all over the world and the day and night are of equal length.

• How high the Sun rises depends on latitude.

• For regions within the Tropics, the day on which the Sun comes exactly overhead depends on the exact locations and 2 such days occur in a year.

• For regions in the North, Summer Solstice is the day of highest sunrise and for the South it is the Winter solstice (as experienced in the North).

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7 Date and Time of Solstice and Equinox

Equinox Solstice Equinox Solstice Sun and seasons year Mar June Sept Dec day time day time day time day time 2002 20 19:16 21 13:24 23 04:55 22 01:14 • Any observer will notice this drift of the Sunrise point 2003 21 01:00 21 19:10 23 10:47 22 07:04 (against the background geography) and its relation to 2004 20 06:49 21 00:57 22 16:30 21 12:42 2005 20 12:33 21 06:46 22 22:23 21 18:35 seasons. 2006 20 18:26 21 12:26 23 04:03 22 00:22 2007 21 00:07 21 18:06 23 09:51 22 06:08 2008 20 05:48 20 23:59 22 15:44 21 12:04 • If you reside in cold regions outside the tropics, Sun, 2009 20 11:44 21 05:45 22 21:18 21 17:47 and its location become more important than the 2010 20 17:32 21 11:28 23 03:09 21 23:38 Moon. 2011 20 23:21 21 17:16 23 09:04 22 05:30 2012 20 05:14 20 23:09 22 14:49 21 11:11 2013 20 11:02 21 05:04 22 20:44 21 17:11 • These cultures therefore become Sun worshipers. 2014 20 16:57 21 10:51 23 02:29 21 23:03

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Winters and Summers Sun and Rashis

• For Northern Hemisphere, winter is the time the • The constellations at Sunrise change with time. Sun spends south of equinox. • The constellations on the Sun’s path ( Rashis ) are so designed that in 1 lunar Synodic month (30 days) the Sun moves 1 Rashi . There are 12 Rashi . • By this count, there are 187 days for summer and 178.4 for winter. The winters are shorter • Since 360 < 365, seasons begin to drift 6 to 7 and colder in the northern hemisphere. days/year and in 5 years, addition of a month is required to synchronise the calendar with the seasons.

• This is called the intercalary month.

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8 Sun and Moon together

• When the Moon returns to a Nakshatra it doesn’t have the same phase • Phase of the Moon is decided by its distance from the Sun • At each of Full Moon, the Moon is 2.25 Nakshatras away from the previous Full Moon, and the Sun is 1 Rashi ahead ( Rashis are defined that way) • Sun and Moon move in the same direction suggests that the Earth is spinning in the same direction as it is rotating. • The Sun’s plane (Orbital plane of the Earth around the Sun or the Ecliptic) is inclined to the Moon’s path by 5 o.

• Point of intersection of the two planes are called the nodes . These nodes are called Rahu and Ketu. These nodes rotate with a period of 18.6 years.

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Celestial Equator and Ecliptic Ecliptic and Orbit of Moon

NCP NCP Ketu (Descending Node) at VE

Lunar Orbit Ecliptic Ecliptic

SS

Celestial Equator Celestial Equator AE

Angle VE between the o WS two is 23.5

Motion of Sun VE = Vernal Equinox and Moon SS = Summer Solstice AE = Autumnal Equinox WS = Winter Solstice Rahu (Ascending Node) at VE Hrishikesh Joglekar Origins of Astronomy 35 Origins of Astronomy 36

9 Ecliptic and Orbit of Moon Ecliptic and Orbit of Moon

NCP NCP

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Ecliptic and Orbit of Moon Ecliptic and Orbit of Moon

NCP NCP

Rahu (Ascending Node) at WS Origins of Astronomy 39 Origins of Astronomy 40

10 Ecliptic and Orbit of Moon Ecliptic and Orbit of Moon

NCP NCP

Rahu (Ascending Node) at AE Origins of Astronomy 41 Origins of Astronomy 42

Ecliptic and Orbit of Moon Ecliptic and Orbit of Moon

NCP NCP

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11 Ecliptic and Orbit of Moon Ecliptic and Orbit of Moon

NCP NCP

Rahu (Ascending Node) at SS Origins of Astronomy 45 Origins of Astronomy 46

Ecliptic and Orbit of Moon Ecliptic and Orbit of Moon

This complete cycle NCP takes 18.6 years NCP

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12 Planets Planet periods

• Of the ~ 6,000 stars visible at night (from ~ 10 22 stars), • Mercury goes around the Sun 88 (earth) in days. there are 5 objects apart from Sun and Moon which are not • Venus takes 0.61 (earth) years stationary. They are called Planets . • Mars takes 1.88 (earth) years • These are Mercury, Venus, Mars, Jupiter and Saturn. • Jupiter takes 11.9 (earth) years • Saturn takes 29.4 (earth) years • Their path is not random. They move more or less on the same path as the Sun and the Moon. • Mercury goes 30 o from the Sun • Venus goes 60 o from the Sun • Mercury moves the fastest and Saturn the slowest.

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Ancient Calendars Making calendars • Vedanga Jyotish (1200 BC) This is the oldest Lunar calendar. It contains a 5-year Yuga of 62 synodic lunar months. • In order to keep track of time over long periods • Brihaspati samvatsar (year) chakra: 60 year cycle of Jupiter. The years of years, a method of counting has to be have names like ‘Prabhav’, ‘Vibhav’ etc. devised. This is called a calendar . • The Griha-parivritti cycle: It consist of 90 solar years. The length of 1 year being 365.2586 days. The year commences with sun entering • Apart from counting, special markers are Mesha (Aries sign). This type of calendar is used in southern peninsula of India especially in Tamilnadu. introduced to ensure that the counting is correct. • Saptarshi era: consists of cycles of 2700 years. It originated with the supposition that seven Rishis stay in each Nakshatra for 100 years. This era was in use in Kashmir. • It also encourages study of rare events by • The currently used calendar is Luni-solar calendar in which each pointing out their rarity. month is synodic lunar month of 29.5 days. One year consists of 12 such months = 254 days. The remaining 11 days of the year are adjusted in Adhik maas (intercalation month) that occur generally in Origins of Astronomy 51 the 3rd, 5th, 8th,11th,14th,16thOrigins and of Astronomy 19 year cycle of years. 52

13 The Saptarshi Era Saptarshi Era

• An interesting time line in the Vedic literature is the Saptarshi Era.

• It states that the Saptarshi constellation moves into different Nakshatras giving different eras. It is generally assumed to be wrong.

• However, the exact manner of the definition clearly shows that the starting date of the Era is 2300 BC and originates in southern Gujarat.

(Sule, Vahia, Bhujle, 2005) 2100 BC 2000 AD

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Yuga in Vedic Literature Yuga: Recent interpretation • There are 4 Yugas the duration scale of 4:3:2:1 • Satya Yuga or Krita Yuga (1,728,000 years), • Yuga concept is introduced in Vedic astronomy • Treta Yuga (1,296,000 years) , to synchronise solar and lunar calendars. • Dvapara Yuga (864,000 years) • The yuga period of five years, whose • Kali Yuga (432,000 years) constituent years are called samvatsara , • Satya Yuga or Krita Yuga - dhyana (meditation) parivatsara , idavatsara , anuvatsara , and • Treta Yuga - yajna (sacrifice) idvatsara , has been in use since Vedic times. • Dvapara Yuga - archana (worship) • Kali Yuga - daana (alms) • However, there are actually 1826.2819 days in a yuga of five solar (sidereal) years. • More acceptable interpretation is that they are Daivik years or days. This Furthermore, there are 1830.8961 days in a gives Yugas to be 1200: 2400: 3600: 4800 years (total 12,000 years). period of 62 lunar months. It is suggested that • It is believed to have begun with the death of Krishna in 3102 BC?????. ~4.5 days were dropped as ‘reset error’. • This reference of time is still used in religion and literature.

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14 Calendars in use

• The Vikram era: – Begins with the coronation of King Vikramaditya. – The year 1900 AD corresponds to 1958 of the Vikram era, – It is popular in northern India and Gujarat.

• The Saka era : – Begins with King Salivahana's accession to the throne. – The year 1900 AD would be 1823. – Popular in southern India, this reference in almost all- astronomical works in Sanskrit written after 500 AD. – The Government calendar also follows the Saka era.

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NORTH

South

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15 Rohini Shakat Bhed

• Rohini Shakat Bhed is defined as an event where Saturn or Mars came inside the triangle of Rohini. • Calculations with modern ephemeris, its occurrence can be dated. • The event last occurred in 5284BC and then 9339 BE prior to that.

Origins of Astronomy 61 (Mahajani, Vahia, Apte and Jamkhedkar,Origins of Astronomy 62 2005)

Nakshtras Vernal Equinox • Nakshatras are the path of Moon in the night sky. Zodiacs are the path of the Sun in the night sky. • Zodiacs were designed in Babylonia before 3000 BC. • Nakshatras appeared fully defined in Babylonia after 1000 BC. • Zodiacs are needed for people preoccupied with Seasons while Nakshatras are needed for people interested in calendar and time keeping. • Nakshatras therefore seem to be Harappan in origin who were sea fearers. Summer solstice

Avg Value VS Year from 3500 BC-2000 AD

5.00 4.50 4.00 THERE IS CLEAR EVIDENCE 3.50 3.00 2.50 THAT NAKSHATRAS WERE 2.00 peak` 1.50 DESIGNED AROUND 3000 1.00 0.50 0.00 BC. Moon's Value Avg at Dec of -4000 -3500 -3000 -2500 -2000 -1500 -1000 -500 0 500 1000 1500 2000 2500 Year

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16 Outstanding issues

• Impact of astronomy on residential and burial sites • Origins of astrology Isn’t this more than enough for 1 • Affects of precession on the seasons lecture? • Mythologies, symbolisms and formalisation of astronomy • Records of comets and supernovae

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Acknowledgements

• I want to acknowledge all the known and unknown Web sources that I have used in the lecture. • My special thanks to WIKIPEDIA which provided some valuable information. • I want to thank my friends Sudha Bhujle, Kavita Gangal, Hrishikesh Joglekar, Parag Mahajani, Aniket Sule. I have stolen ideas and images from all of them!

• I want to particularly thank Dr. Jamkhedkar who has been my constant source of inspiration on this subjects.

• I want to express my apology to all those whom I may have forgotten to thank.

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