Indian Astronomy through Observations from Ancient Periods

Jain University / Sep-Oct 2024

Sunder Chakravarty , CAHC, Jain University

Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Outline of the talk

Topic Info Slides Minutes
Lecture 1 (~15 slides in ~60 minutes) --- ---
Objects Sun, Moon, Stars, Nakṣatras, Grahas(planets), etc 2 10
Sun's Rhythms Ahorātrā(day), Ayana, Ṛtu(seasons), Samvatsara(year) 6 30
Rhythms of Nakṣatras and Stars Ecliptic , Ecliptic Stars, Fixed Dhruva and the Slow Drift of Dhruva 6 30
Stellarium on Phone and PC Observing the sky digitally 2 10
Topic Info Slides Minutes
Lecture 2 (~15 slides in ~60 minutes) --- ---
Moon's Rhythms Tithi, Pakṣa(fortnight), Māsa(month), Lunar Eclipse 6 30
Rhythms of Grahas Visibility, Vakra(Retrograde), Prograde, 6 30
Eclipse and their Rhythms Solar, Lunar 6 30
Calendar Systems Lunar, Solar, Luni-Solar 6 30
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

What the Ancients Observed
पृथिवि Earth Where we are firmly grounded
Contains rivers, mountains, plants, animals, people etc
आकाशः / द्यौः Sky the sun dominates during daytime,
creating dawn, dusk, seasons
the moon waxes and wanes in cycles night over night
creating phases
the stars emerge in the night
forming recognizable patterns
अन्तरिक्षः Space-in-between the clouds exists bringing rains
the meteors shower through
occasionally bringing disasters

Astronomy is a result of these observations and ponderings, started by the ancients and continually refined since.

Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Purpose of these Observations

  1. Pursue curiosity
  2. Answer questions like
    1. Where will the sun rise tomorrow
    2. What will be the moon’s phase tomorrow
    3. How many days hence is the next full moon
    4. How many days to the next rainy period
    5. When to sow seeds
    6. What is my birth nakshatra
    7. How does my birth nakshatra affect me
    8. How will the faded sun/moon impact the ruler/people
    9. When, what and whom to offer to adduce desired outcome

The greens need observation and calculation - Astronomy

The blues need additional interpretation - Astrology

Ancient Indian Astronomy - Jain University IKS - 2024-09-09

A long tradition of Jyotishi-s

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  • Jyotishi-s are the Indian astronomers
  • Some are very famous like Aryabhata, Varahamihira, Brahmagupta, Bhaskara I, II etc
  • Others are less known like Lalla, Bhattotpala, etc
  • This academic tradition faded about three centuries ago
  • Interest is now being revived
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Sun's rhythms - ayanas, ṛtus, nakṣatras, drift of ṛtus

Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Few Sun names - various qualities
(some qualities observed, others inferred)
सूरः सूर्यः अर्यमा आदित्यः द्वादशात्मा
दिवाकरः भास्करः अहस्करः ब्रध्नः प्रभाकरः
विभाकरः भास्वान् विवस्वान् सप्ताश्वः हरिदश्वः
उष्णरश्मि विकर्तनः अर्कः मार्तण्डः मिहिरः
अरुणः पूषः द्युमणिः तरणिः मित्रः
चित्रभानुः विरोचनः विभावसुः ग्रहपतिः त्विषाम्पतिः
अहर्पतिः भानुः हंसः सहस्रांशुः तपनः
सवितृ रविः पद्माक्षः तेजसांराशिः छायानाथः
तमिस्रहन् कर्मसाक्षी जगच्चक्षुः लोकबन्धुः त्रयीतनुः
प्रद्योतनः दिनमणिः खद्योतः लोकबान्धवः ज्योतिष्मान्
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Observing the Sun's rhythmns
The Sun rises in the east eastern horizon and sets in the west western horizon
Season Sunrise Sunset
End-Summer north-eastern horizon north-western horizon
Mid-Spring/Autumn exact east exact west
Start-Winter south-eastern horizon south-western horizon

Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Annual Sunpath

img

  • Video of ~2 minutes shows
  • Sun's daily path for few evenly spaced days through the year
  • The contrast between the summer and winter paths can be seen
  • The contrast between the Bangalore and Kurukshetra paths can be seen
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

A Clock with more features - The Celestial Clock

  • The sky is a hemisphere above us
  • Stars are painted on the sky
  • A band of stars around the east-west arc is the ecliptic
  • The ecliptic can be thought of as the dial of a clock
  • The stars on the ecliptic are the nakṣatra-s - much like the numbers on a clock
  • The sun, moon and gruhas moves along the ecliptic - like hand tips on a clock
Alarm Clock Celestial Clock
Dial Ecliptic
Numbers Nakṣatra-s
Hands Sun, Moon, Gruhas
Slow Hour Hand Sun Annual run clockwise
Fast Minute Hand Moon Monthly run clockwise
Cycling through it phase about every month
~ no equivalent ~ Gruhas travelling different speeds
going anticlockwise sometimes
going invisible sometimes
~ no equivalent ~ Precession
The dial itself rotates anticlockwise very very slowly
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Sun and Nakṣatras

We noted that each of the 366 sunrises occurs at different points on the eastern horizon due to the sun's swing. In addition, the stars that are visible just prior to each sunrise at the sunrise point also change. The stars that are visible just prior to sunrise are said to belong to the solar nakṣatra of that day.

A nakṣatra is a span of time of about 14 days for the sun, and contains the stars that are visible at sunrise in its time span. There are 27 such equal nakṣatra spans in a 366 day cycle.

Each of the 27 nakṣtra while of equal time span contains varying counts of stars - between 1 and 6 - totaling 83 stars. A nakṣatra is therefore a span of space in the sky as well.

The 27 nakṣatras are named in a fixed cyclical order. The current order starting from Aśvinī along with their star count listed below, is an inherited order from around 1500 years ago. The order of the nakṣatra begins with Kṛttikā and ends with Bharanī in more ancient texts.
Aśvinī
3		 Bharaṇī
3		 Kṛttikā
6		 Rohiṇī
5		 Mṛgaśiras
3		 Ārdrā
1		 Punarvasu
2		 Puṣya
1		 Aśleṣā
6
Maghā
6		 Pūrva
Phalgunī
2		 Uttara
Phalgunī
2		 Hasta
5		 Citrā
1		 Svātī
1		 Viśākhā
2		 Anurādhā
4		 Jyeṣṭhā
3
Mūla
4		 Pūrva
Aṣāḍhā
4		 Uttara
Aṣāḍhā
4		 Śravaṇa
3		 Śraviṣṭhā
4		 Śatabhiṣā
1		 Pūrva
Bhādrapadā
2		 Uttara
Bhādrapadā
2		 Revatī
1

The choice of the first nakṣatra to start the cycle contains information on the epoch and the convention for the year start.

There are texts that associate specific nakṣatras with the ṛtus - seasonal naḳsatras . Such seasonal naḳsatras also contain vital information on the epoch of the text.

Ancient Indian Astronomy - Jain University IKS - 2024-09-09

The Sun, Ṛtus and Nakṣatras

  • Video of ~1½ minutes shows

  • Per year sun covers

    • 2 ayanas
    • 6 ṛtu-s
    • 27 nakṣatra-s
    • Rtu-s & nakṣatra-s are associated

  • Over millenia,

    • the nakṣatra-s drift slowly due to precession
    • This change is used to date the ancient texts
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Recap - Sun's rhythms

Every day

  • Sunrises in the east creating day
  • Sunsets in the west ushering night
  • Sunrise and sunset positions change daily

Just before every sunrise

  • One can observe eastern horizon star changes

Every ~14 days

  • Sun moves through a nakṣatra

Every ~366 days

Sunrise completes one full swing along the eastern hor
izon

  • A northern swing called uttaryāṇa for 183 sunrises
  • A southern swing called dakṣiṇāyana for 183 sunrises
Start of uttaryāṇa/dakṣiṇāyana solstice winter/summer
Mid of uttaryāṇa/dakṣiṇāyana equinox spring/autumn

Sun cycles through

  • 6 ṛtu-s of 61 sunrises each vasanta, grīṣma, varṣā, śarat, hemanta, śiśira
  • 27 nakṣatra-s - the same eastern horizon star appears just before sunrise

Occasionally

  • Sun goes partially or fully dark before recovering - Eclipse

Every 1000 years

  • The spring equinox nakṣatra moves backward by one naḳsatra due to precession
  • i.e. seasons move backward by one naḳsatra
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Effect of precession over millennia

  • About every 1000 years the start of seasons move backward by one naḳsatra. In addition the precession causes the pole star to change.

  • The following table/pictures shows the start of the spring equinox seasonal naḳsatra and the pole star for the last 5000 years.

Epoch Spring Equinox Dakṣiṇāyana Uttaryāṇa Pole Star Image
Present Uttara Bhādrapadā Ārdrā Mūla Polaris
1000 years ago Revatī Punarvasu Pūrva Aṣāḍhā -
2000 years ago Aṡvinī Puṣya Uttara Aṣāḍhā -
3000 years ago Bharanī Aśleṣā Śravaṇa -
4000 years ago Kṛttikā Maghā Śraviṣṭhā -
5000 years ago Rohiṇī Pūrva Phalgunī Śatabhiṣā Thuban
Present Day
5000 years ago
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Recall questions

# Question
1 What is an ayanā?
2 How many nakṣatra-s and seasons in one ayanā?
3 What is the duration of one ṛtu?
4 What is the most pleaseant ṛtu? Which among the four solstices/equinox is it associated with?
5 Solsitices means still-sun. Using swing in park/tree analogy, explain why it is so.
6 How many times does the sun rise in a year? How many are those are closest to true east?
7 What is a nakṣatra? Is it a time span or a space span? How many stars are there in a nakṣatra?
8 What is the current start order of the nakṣatra-s? What is the start order in more ancient texts?
9 What is the significance of the first nakṣatra in the cycle?
10 How is precession of the equinoxes used to date ancient texts?
11 List five names of the sun and their qualities.
12 What is the difference between astronomy and astrology as we understand it today?
13 What is the significance of the pole star in the sky?
14 What is your birth nakṣatra? What does it mean to you?
15 What is the significance of the ecliptic in the sky?
16 Name a few ancient astronomers and their contributions.
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Stellarium on phone and/or PC
Observing the sky digitally

End of Lecture 1

Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Outline - Lecture 2

Topic Info Slides Minutes
Lecture 2 (~7 slides in ~60 minutes) --- ---
Recap Lecture 1
Moon's Rhythms Tithi, Pakṣa(fortnight), Māsa(month) 3 30
Calendar Systems Lunar, Solar, Luni-Solar 3 30
Hands on Stellarium Observing the sky digitally 1 10
Rhythms of Grahas Visibility, Vakra(Retrograde), Prograde, 6 30
Eclipse and their Rhythms Solar, Lunar 6 30
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Recap

Topic Info Slides Minutes
Lecture 1 (~15 slides in ~60 minutes) --- ---
Objects Sun, Moon, Stars, Nakṣatras, Grahas(planets), etc 2 10
Sun's Rhythms Ahorātrā(day), Ayana, Ṛtu(seasons), Samvatsara(year) 6 30
Rhythms of Nakṣatras and Stars Ecliptic , Ecliptic Stars, Fixed Dhruva and the Slow Drift of Dhruva 6 30
Stellarium on Phone and PC Observing the sky digitally 2 10
# Question
1 What is an ayanā?
2 How many nakṣatra-s and seasons in one ayanā?
3 What is the duration of one ṛtu?
4 What is the most pleaseant ṛtu? Which among the four solstices/equinox is it associated with?
5 Solsitices means still-sun. Using swing in park/tree analogy, explain why it is so.
6 How many times does the sun rise in a year? How many are those are closest to true east?
7 What is a nakṣatra? Is it a time span or a space span? How many stars are there in a nakṣatra?
8 What is the current start order of the nakṣatra-s? What is the start order in more ancient texts?
9 What is the significance of the first nakṣatra in the cycle?
10 How is precession of the equinoxes used to date ancient texts?
11 List five names of the sun and their qualities.
12 What is the difference between astronomy and astrology as we understand it today?
13 What is the significance of the pole star in the sky?
14 What is your birth nakṣatra? What does it mean to you?
15 What is the significance of the ecliptic in the sky?
16 Name a few ancient astronomers and their contributions.
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Moon and Sun - Hide and seek

Clock Analogy

The fast moon overtakes the slow sun every month much like a fast minute hand overtakes a slow hour hand every hour

Thithi Sun Moon Separation Moon rise Moon Overhead
🌑 Amavāsya is when the moon is closest to the sun 0° Together with Sunrise Mid noon
🌓 Śukla Aṣṭamī is when the moon is 90° from the sun 90° 6 hours after sunrise (mid noon) around 6 pm
🌕 Pūrnima is when the moon is farthest from the sun 180° Opposite with Sunset Mid night
🌗 Kṛṣṇa Aṣṭamī is when the moon is 270° from the sun 270° 6 hours before sunrise (mid night) around 6 am
Starts Ends Contains
Śukla Pakṣa amāvāsya+1 pūrnima 15 Śukla tithis Moon moving away from sun
Kṛṣṇa Pakṣa pūrnima+1 amāvāsya 15 Kṛṣṇa tithis Moon moving towards sun

15 Thithis and their early names Nanda ... Pūrṇā

नन्दा भद्रा जया रिक्ता पूर्णा
प्रथमा/प्रतिपदा द्वितीया तृतीया चतुर्थी पञ्चमी
षष्ठी सप्तमी अष्टमी नवमी दशमी
एकादशी द्वादशी त्रयोदशी चतुर्दशी पूर्णिमा/अमावास्या
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Moon and Months

मासः மாதம் ತಿಂಗಳು month - all units of time from the word for moon
चन्द्रमासः mean 29.5 days From one pūrnima/amavāsya to the next चैत्रः वैशाखः ज्येष्ठः आषाढः श्रावणः भाद्रपदः आश्विनः कार्तिकः मार्गशीर्षः पौषः माघः फाल्गुनः

ಚೈತ್ರ ವೈಶಾಖ ಜ್ಯೇಷ್ಠ ಆಷಾಢ ಶ್ರಾವಣ ಭಾದ್ರಪದ ಆಶ್ವಯುಜ ಕಾರ್ತೀಕ ಮಾರ್ಗಶಿರ ಪುಷ್ಯ ಮಾಘ ಫಾಲ್ಗುಣ

Full Moon approximately near the nakṣatra that names the month
स्तृमासः mean 27.3 days From one nakṣatra to the same
सौरमासः 29 to 32 days sun based मेषः वृषभः मिथुनः कटकः सिंहः कन्याः तुला वृश्चिकः धनुः मकरः कुम्भः मीनः

சித்திரை வைகாசி ஆனி ஆடி ஆவணி புரட்டாசி ஐப்பசி கார்த்திகை மார்கழி தை மாசி பங்குனி

മേടം ഇടവം മിഥുനം കർക്കിടകം ചിങ്ങം കന്നി തുലാം വൃശ്ചികം ധനു മകരം കുംഭം മീനം

मधुः माधवः शुकः शुचिः नभः नाभः इषः उर्जः सहः सहस्यः तपः तपस्यः
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Panchāṅga - a Calendar System

  • Each Sunrise has an associated Tithi, Vāra, Nakṣatra, Yoga, Karana. These are the five limbs of the Panchāṅga.

  • Each of these limbs are either observed or compute/derived from the positions of the Sun and Moon in the sky.

  • Panchāṅga is a calendar system that is used to track time and events. It is also used to determine the auspicious and inauspicious times for various activities.

  • This five limb system is relatively modern ( post अर्थशास्त्रः ) and used in various forms across India and South East Asia.
तिथिः 30 Moon Phase Observable प्रथमा/प्रतिपदा द्वितीया तृतीया चतुर्थी पञ्चमी षष्ठी सप्तमी अष्टमी नवमी दशमी एकादशी द्वादशी त्रयोदशी चतुर्दशी पूर्णिमा/अमावास्या
नक्षत्रम् 27 Moon's companion Observable अश्विनी भरणी कृत्तिका रोहिणी मृगशीर्ष आर्द्रा पुनर्वसु पुष्य आश्लेषा मघा पूर्वफल्गुनी उत्तरफल्गुनी हस्त चित्रा स्वाति विशाखा अनुराधा ज्येष्ठा मूल पूर्वाषाढा उत्तराषाढा श्रवण श्रविष्ठा शतभिषा पूर्वभाद्रपद उत्तरभाद्रपद रेवती
वारः 7 Sequence repeats every 7 sunrises Lord of the day Not observable रविवासरः सोमवासरः मङ्गलवासरः बुधवासरः गुरुवासरः शुक्रवासरः शनिवासरः
योगः 27 Derived from Sun and Moon position Used mainly in फलितम् Not Observable विष्कुम्भः प्रीतिः आयुष्मान् सौभाग्यः शोभनः अतिगण्डः सुकर्मा धृतिः शूलः गण्डः वृद्धिः ध्रुवः हर्षणः वज्रः विष्टिः सिद्धिः व्यतीपातः वरीयान् परिघः शिवः सिद्धः साध्यः शुभः शुक्लः ब्रह्मा इन्द्रः वैधृतिः
करणम् 11 Half of a tithi Used mainly in फलितम् Not Observable बवः बालवः कौलवः तैतिलः गरः वणिजः विष्टि/भद्रा
शकुनि चतुष्पाद् नागः किंस्तुघ्नः
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

A sample month

  • Calendar by Dr Guha Vishwanathan MV
  • 1947 शालिवाहनसंवत्सरः, 2024 Gregorian , 2081 विक्रमसंवत्सरः
  • Notice the Tithi, Vāra, Nakṣatra, Gregorian day for each day
  • Notice where each of these start and end
  • Notice the Pakṣa and the Māsa for each day
  • Find the Sunrise and Sunset markers for each day

img scale

Ancient Indian Astronomy - Jain University IKS - 2024-09-09

A sample day (drigpanchang.com)

  • Phalguna 22, 1945 Shaka - Mar/12/2024
  • Notice the Tithi, Vāra, Nakṣatra, Yoga, Karaṅa for each day
  • Notice this Tithi is trapped between two Sunrises . It a kśaya tithi
  • Some thithis can consume two sunrises
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Calendar Systems in India

  • Luni-Solar Both Sun and Moon are used to determine the year and month - Panchāṅga
  • Lunar Only Moon is used to determine the year and month - Islamic
  • Solar Only Sun is used to determine the year and month - Gregorian
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

New year in India

  • Mesha Sankranti is the new year in many parts of India - Solar Event
  • Chaitra 1/Ugadi is the new year in many parts of India - Luni-Solar Event
  • January 1 is the new year in many parts of India - Gregorian/Solar Event
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Stellarium on phone and/or PC
Observing the sky digitally

- Locate the Sun using Stellarium now

- What was the sun rise time today?

- What is the nearest nakṣatra to the moon today?

- Locate the pole star in the sky in the day time and night time

Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Recall questions - Lecture 2

# Question
1 What is a tithi?
2 What is a pakṣa?
3 What is a māsa? How many types are there.
4 What is the difference between a lunar, solar and luni-solar calendar?
5 What is the difference between a panchāṅga and a calendar?
6 What are the five āṅga of a panchāṅga?
7 Which of the five āṅga are observable and which are computed?
8 How many tithis are there in a māsa?
9 Using drigpanchang.com, locate your birth event. What is the tithi, vāra, nakṣatra, yoga and karaṇa ?
10 How many years, चन्द्रमासः and स्तृमासः in 1830 days to the nearest integer
11 Name 3 states following amanta , pūrṇimānta and saura māsa-s.
12 What are rāka anumati kuhu and sinīvālī?
13 Around what time can the moon be seen overhead during Rama-navamī and Krishna-aṣṭamī.
14 Discuss the various new year events in India
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

End of Lecture 2

Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Outline - Lecture 3

Topic Info Slides Minutes
Recap Lecture 2
Moon's Rhythms Tithi, Pakṣa(fortnight), Māsa(month) 3 30
Calendar Systems Lunar, Solar, Luni-Solar 3 30
Hands on Stellarium Observing the sky digitally 1 10
Lecture 3 (~7 slides in ~60 minutes) --- ---
Rhythms of Grahas Visibility, Vakra(Retrograde), Prograde 6 30
Eclipse and their Rhythms Solar, Lunar 6 30
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

ग्रहाः Grahas
ग्रहः From the धातु ग्रह् to grasp, to seize, to hold
अथर्ववेदपरिशिष्टम्
(५२,११.४) कूटस्थेष्वप्रसन्नेषु स्थावरं परिहीयते । आदित्यश्चैव शुक्रश्च लोहिताङ्गस्तथैव च ॥
(५२,११.५) राहुः सोमः शनैश्चरो बृहस्पति बुधौ तथा । ऐन्द्र आग्नेयो याम्यश्च नैरृतो वारुणस्तथा ॥
(५२,१२.१) वायव्यश्चैव सौम्यश्च ब्राह्मश्चैवाष्टमो ग्रहः । नवमश्चैव विज्ञेयो धूमकेतुर्महाग्रहः ॥
श्रीविष्णुधर्मोत्तरे प्रथमखण्डे द्विसप्ततितमोऽध्याये
नामसंख्या बुधैर्ज्ञेया ग्रहगत्यनुसारतः ॥
तत्र ताराग्रहाः पञ्च द्वौ च ज्ञेयौ महाग्रहौ ॥७ ॥
उपग्रहौ च द्वौ ज्ञेयावेवं प्रोक्ता नव ग्रहाः ॥
भौमज्ञजीवभृगुजसौरास्ताराग्रहास्स्मृताः ॥८ ॥ there 5 tārāgrahas here - but the text is not clear
चन्द्रा-दित्यौ तथा राम विज्ञेयौ द्वौ महाग्रहौ ॥
उपग्रहौ च द्वौ ज्ञेयौ राहुः केतुश्च भार्गव ॥९ ॥
5 ताराग्रहः Grasps the stars मङ्गलः बुधः गुरुः शुक्रः शनिः
2 महाग्रहाः The dominant ones सूर्यः चन्द्रः
2 छायाग्रहः / उपग्रहः Shadowy graspers राहुः केतुः
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Grahas in Parāśaratāntram

ग्रहः PT Info Modern Info Modern
Symbol
सूर्यः Sun 1 year
Indicates Seasons		 ~1 year
-		 ☉
चन्द्रः Moon 1 month
Moon Horn's and taragrahas portends		 ~1 month
-		 ☽
मंगलः Mars Vakra paths described - zig-zag, hilt paths can be observed ♂
बुधः Mercury 7 paths 7 visible windows per year ☿
गुरुः Jupiter Moves 2¼ nakṣatras per year
Rohiṇī occultation is bad omen		 ~12 years
-		 ♃
शुक्रः Venus Visibility: east(↑270 ↓68) west(↑240 ↓13)
If seen all day invader trouble for cities/villages;
Lots of connection to rainfall		 east(↑263 ↓50) west(↑263 ↓9)
-
-
-		 ♀
शनिः Saturn 30 years
Invisible to about 30 days each year		 ~30 years
Consistent with modern		 ♄
राहुः North Node 10 types ग्रसना रोहणो पघ्रातो न्मर्दन निरोध परिलेहना पसव्य सव्या न्तर्मध्यतम उपप्लवाश्च
Six colors of lunar eclipse
Lunar Eclipse every 6 months for 3.5 years		 Can be Reasoned ☊
केतुः South Node? 11classes 101comets अथैकादशजातय एकोत्तरशतकेतवो भवन्तीति पराशरादीनां मतम्
Detailed description of shape color periodicty and portend		 Ketu is now considered to cause lunar eclipse. This is unfortunate. The tradition of comet study got lost ☋
Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Movement of Gruhas in Āryabhaṭīya/Sūrya Siddhānta

Pictures sourced from https://people.highline.edu/iglozman/classes/astronotes/media/retro_epicycle.jpg and
https://maghaa.com/wp-content/uploads/2018/05/Picture36.png

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Ancient Indian Astronomy - Jain University IKS - 2024-09-09

The path of Venus
Venus is the only planet that can be seen in the day time.
It is the brightest object in the sky after the sun and moon
It can be seen in the morning and evening and never overhead unless there is total solar eclipse
Bright enough to cast shadow in ideal conditions
It has phases like the moon when seen through telescope
It has a 8 year cycle of 5 periods of 584 days each ( 263+50+263+8)

Images from scarednumbers and bobmoler

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Ancient Indian Astronomy - Jain University IKS - 2024-09-09

The path of Grahas
Mercury and Venus are inner grahas
The others are outer
Mercury and Venus are never seen overhead
The picture show 1 year of Mercury and 8 Venus path
Mars for 22? years, Jupiter for 12 and Saturn 30

Image from reddit

Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Why is every full/new moon not an eclipse?
The moon's orbit is tilted by about 5° to the earth-sun plane ecliptic
The nodes are the points where the moon's orbit lies on the ecliptic
The ascending node is called Rāhu and the descending node is called Ketu
Solar eclipses occur new moon is near Rāhu or Ketu
Lunar eclipses occur when the full moon is near Rāhu or Ketu
Every 18 years, the moon's nodes return to the same nakṣatra - 3339 krishna pakṣa tithis
RV 10.52.6 त्रीणि॑ श॒ता त्री स॒हस्रा॑ण्य॒ग्निं त्रिं॒शच्च॑ दे॒वा नव॑ चासपर्यन् ।		 
 The picture below is from wikipedia

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Ancient Indian Astronomy - Jain University IKS - 2024-09-09

Recall questions - Lecture 3

# Question Answer
1 What is a graha? A graha is a celestial body that grasps or seizes other celestials
2 What are the 5 tārāgrahas? मङ्गलः बुधः गुरुः शुक्रः शनिः
3 What are the 2 mahāgrahas? सूर्यः चन्द्रः
4 What are the 2 upagrahas/chāyāgrahas? राहुः केतुः
5 What is the difference between a tārāgraha and a mahāgraha? Tārāgrahas are the 5 that grasp the stars. Mahāgrahas are the sun and moon that are the dominant ones.
6 What are other names of मङ्गलः , बुधः मङ्गलः(अङ्गारकः, कुजः, भौमः, लोहिताङ्गः, महीसुतः) बुधः(रौहिणेयः, सौम्यः)
7 What is शनिः named so? The name शनिः is derived from the word शनैः चरति - moves slowly
8 Which gruhas can never be seen overhead apart from राहुः and केतुः बुधः and शुक्रः . Because they are inner grahas
9 What is the difference between a solar and lunar eclipse? Solar eclipse is when the moon is between the sun and the earth. Lunar eclipse is when the earth is between the sun and the moon.
10 What is a necessary condition for an eclipse to occur? A straight line must connect sun, earth and moon.
11 How many types of eclipses does पराशरतंत्रम mention? 10 types of Lunar eclipses. grasping, mounting, smelling (upaghrāta), pressing (unmardana), cover (nirodha), licking (parileha), clockwise, anti-clockwise, ring, and total darknes
Ancient Indian Astronomy - Jain University IKS - 2024-09-09