Zero Shadow Day

When the Sun is right overhead

When the Sun is right overhead.
© A. Paranjpye

“I thought the most beautiful thing in the world must be shadow.” - Sylvia Plath, The Bell Jar

The lack of shadow is beautiful too. And it happens twice a year, for places between +23.5 and -23.5 degrees latitude. The Sun is almost never exactly overhead at noon, but usually transits a bit lower in altitude, a bit to the north or a bit to the south. We have all studied in school that the Earth's rotation axis is inclined at 23.5 degrees to the plane of its revolution around the Sun, which is why we have seasons. This also means that the Sun, in its highest point of the day, will move from 23.5 degrees south of the celestial equator to 23.5 degrees north of the equator (Uttarayan), and back again (Dakshinayan), in a year. Of course, the northern most and southern most points are the two solstices, and the crossing of the Sun across the equator are the two equinoxes.

For people living between +23.5 and -23.5 degrees latitude, the Sun's declination will be equal to their latitude twice - once during Uttarayan and once during Dakshinayan. On these two days, the Sun will be exactly overhead at noon and will not cast a shadow of an object on the ground. This Zero Shadow Day will clearly be different for different places on earth.
Scroll down below to find your local ZSD, state-wise maps, resource material, and public ZSD events.

When is Zero Shadow Day at your location?

You can find the two Zero Shadow Days at your location using this interactive map made by Alok Mandavgane.

Scroll down to find the nearest place to your location

ZSD Places
6 Apr & 5 Sep Indira Point
10 Apr & 1 Sep Kanyakumari, Nagercoil, Kudankulam, Trinket Island
11 Apr & 31 Aug Kovalam, Trivandrum, Kazhakoottam, Nedumangadu, Sathankulam, Tiruchendur
12 Apr & 30 Aug Varkala, Ponmudai, Paravur, Kollam, Kottarakara, Punalur, Tenkasi, Tirunelveli, Thoothukudi,
13 Apr & 29 Aug Kayankulam, Adoor, Thiruvalla, SankaranKoil, Kovilpatti, Rameshwaram, Ramanathapuram, Car Nicobar
14 Apr & 28 Aug Alappuzha, Kottayam, Vaikom, Pala, Sabarimala, Cumbum, Rajapalayam, Sivakasi, Virudhunagar, Paramakudi
15 Apr & 27 Aug Kochi, Vypin, Thodupuzha, Idukki, Munnar, Theni, Andipatti, Tirumangalam, Madurai, Sivaganga, Karaikudi
16 Apr & 26 Aug Paravur, Aluvag, Chalakudy, Valparai, Kodaikanal, Dindigul, Pudukottai, Pattukottai, Vedaranyam
17 Apr & 25 Aug Guruvayur, Ponnani, Thrissur, Ottapalam, Palakkad, Pollachi, Mettupalayam, Udumalpet, Palani, Trichy, Thanjavur, Thiruvarur, Nagapattinam, Little Andaman
18 Apr & 24 Aug Kottakal, Malappuram, Coimbatore, Gudalur, Palladam, Tiruppur, Kangayam, Karur, Kumbakonam, Mayiladuthurai, Karaikal, Poompuhar
19 Apr & 23 Aug Kozhikode, Koyilandy, Thamarassery, Ooty, Kotagiri, Avinashi, Erode, Tiruchengode, Namakkal, Sirkazhi, Chidambaram
20 Apr & 22 Aug Vadakara, Mahe, Thalassery, Perambra, Wayanad, Mudumalai, Bhavani, Mettur, Salem, Kallakuruchi, Neyveli, Panruti, Cuddalore, Port Blair
21 Apr & 21 Aug Kannur, Payyanur, Taliparamba, Dharmapuri, Sankarapuram, Villupuram, Pondicherry, Havelock Island
22 Apr & 20 Aug Kanhangad, Kasargod, Madikeri, Mysore, Srirangapatna, Shuivanasamudra, Chengam, Tiruvannamalai, Tindivanam, Long Island
23 Apr & 19 Aug Uppala Gate, Puttur, Arakalagud, Krishnarajapete, Melkote, Mandya, Channapatna, Ramanagara, Attibele, Hosur, Krishnagiri, Tirupattur, Vanaiyambadi, Kavalur, Ambur, Arani, Kanchipuram, Chengalpattu, Mahabalipuram, Kelambakkam
24 Apr & 18 Aug Mangalore, Mooadbidri, Bantwal, Sakleshpur, Hassan, Shravanabelagola, Bidadi, Bangaluru, Dasarahalli, Bangarapet, Kolar, Gudiyattam, Vellore, Arcot, Arakkonam, Sriperumbudur, Tiruvallur, Avadi, Chennai, Interview Island, Sound Island
25 Apr & 17 Aug Udupi, Brahmavar, Karkala, Sringeri, Kudremukha, Chickmagaluru, Halebeedu, Arsikere, Tiptur, Tumkur, Doddaballapura, Chickballapura, Chintamani, Chittoor, Thiruthani, Minjur, Pulicat, North Andaman
26 Apr & 16 Aug Kundapura, Trasi, Thirthahalli, Kuppali, Kadur, Tarikere, Sira, Gauribidanur, Peddur, Madanapalle, Tirupati, Srikalahasti, Sriharikota
27 Apr & 15 Aug Bhatkal, Muthala, Shivamogga, Channagiri, Hiriyur, Madakasira, Rayachoty
28 Apr & 14 Aug Honnavar, Kumta, Jog Falls, Shikaripur, Challakere, Kadiri, Nellore
29 Apr & 13 Aug Kumta, Gokarna Sirsi, Ranebennur, Davangere, Anantapur, Cuddapah, Ramathirtham
30 Apr & 12 Aug Karwar, AgondBa, Haveri, Kudigi, Tadipatri. Jammalamadugu, Proddatur, Kavali
1 May & 11 Aug Benaulim, Margao, Dandeli, Hubli, Hospet, Bellary, Guntakal, Gooty
2 May & 10 Aug Panjim. Vasco, Anjuna, Dharwad, Gadag, Gangavathi, Nandyal, Ongole
3 May & 9 Aug Sawantwadi, Belgaum, Sindhanur, Kurnool, Markapur, Chirala, Bapatla
4 May & 8 Aug Malvan, Gokak, Bagalkot, Vinukonda, Chilakaluripet, Machilipatnam
5 May & 7 Aug Devgad, Radhanagari, Mudhol, Raichur, Deosugur, Narasaraopet, Guntur, Mangalagiri, Gudivada
6 May & 6 Aug Ambolgad, Kolhapur, Ichalkaranji, Yadgir, Mahbubnagar, Vijayawada, Eluru, Bhimavaram, Tanuku
7 May & 5 Aug Ratnagiri, Sangli, Miraj, Vijayapura, Nalgonda, Nuzividu, Tadepalligudam, Rajahmundry, Kakinada
8 May & 4 Aug Jaigad, Karad, Afzalpur, Kalburgi, Suryapet, Khammam, Samarlakota
9 May & 3 Aug Chiplun, Mandrup, Akkalkot, Hyderabad, Secunderabad, Kothagudam
10 May & 2 Aug Satara, Pandharpur, Solapur, Basavakalyan, Sangareddy, Jangaon, Palwancha, Visakhapatnam
11 May & 1 Aug Mahabaleshwar, Phaltan, Tuljapur, Medak, Warangal, Vizianagaram
12 May & 31 Jul Mangaon, Baramati, Barshi, Osmanabad, Ausa, Nariapur, Malkangiri, Srikakulam
13 May & 30 Jul Mulshi, Pune, Daund, Latur, Karimnagar, Pamunuru, Sukma, Salur, Bobili
14 May & 29 Jul Alibaug, Lonavla, Talegaon Dabhade, Pimpri Chichwad, Dehu Road, Jamkhed, Ambajogai, Nizamabad, Korutla, Ramagundam, Palakonda
15 May & 28 Jul Mumbai, Navi Mumbai, Karjat, Matheran, Rajgurunagar, Manchar, Ralegan-Siddhi, Beed, Gangakhed, Mancherial, Mandamarri, Dantewada, Jagdalpur, Jeypore
16 May & 27 Jul Borivali, Thane, Dombivili, Kalyan, Bhiwandi, Badlapur, Narayangaon, Khodad, Ahmednagar, Parbhani, Nanded, Nirmal, Mamda, Dudme, Bastar, Nowrangpur, Rayagada, Taptapani, Brahmapur
17 May & 26 Jul Nala Sopara, Virar, Asangaon, Basmat, Kouta, Aheri, Chhota Dongar, Mahulpatna, Pattapur, Ganjam
18 May & 25 Jul Palghar, Kasara Budruk, Sangamner, Shrirampur, Ambad, Hingoli, Adilabad, Mulchera, Koksara, Satapada
19 May & 24 Jul Dahanu, Nashik, Kopargaon, Vaijapur, Aurangabad, Jalna, Pusad, Balharshah, Rowghat, Dharmagarh, Bhawanipatna, Bellaguntha, Puri
20 May & 23 Jul Talasari, Takh, Mehkar, Washim, Wani, Chandrapur, Mul, Keskal, Nayagarh, Motari, Saharabedi
21 May & 22 Jul Bilad, Silvassa, Khedgaon, Manmad, Kannad, Chikhli, Rohna, Wadki, Bhanupratappur, Kanker, Kusuruparaha, Bhubaneswar, Paradeep
22 May & 21 Jul Daman, Vapi, Malegaon, Chalisgaon, Buldana, Khopadi, Yavatmal, Armori, Charama, Saintala, Phulbani, Cuttack
23 May & 20 Jul Diu, Valsad, Bhadgaon, Khamgaon, Akola, Wardha, Kusumkasa, Dhamtari, Balangir, Dhenkanal, Bharcchan
24 May & 19 Jul Somnath, Jafarabad, Navsari, Amalsad, Dhule, Jamner, Shegaon, Nimbora, Wardha, Umred, Kurud, Nuapada, Angul, Bhuban, Jajpur
25 May & 18 Jul Mangrol, Talala, Rajula, Mahuva, Vadoli, Sakri, Amalner, Jalgaon, Bhusawal, Telhara, Amravati, Rajnandgaon, Nawapara Nagar, Padmapur, Bhadrak
26 May & 17 Jul Madhavpur, Datha, Surat, Bardoli, Vyara, Nardana, Chopda, Paratwada, Nagpur, Durg, Bhilai, Bhandara, DOngargarh, Raipur, Barpali, Markona
27 May & 16 Jul Keshod, Savar Kundla, Alang, Nandurbar, Shirpur, Burhanpur, Tumsar, Gondia, Katapali, Chandipur
28 May & 15 Jul Junagadh, Paltana, Ankleshwar, Shahada, Pandhurna, Tilda, Sambalpur, Balasore
29 May & 14 Jul Porbandar, Upleta, Amreli, Bhavnagar, Bharuch, Sendhwa, Chichanda, Bhatapara, Jogal, Digha, Mousuni
30 May & 13 Jul Ghumli, Jamkandorana, Rajpipla, Khargone, Khandwa, Betul, Balaghat, Raigarh, Jharsuguda, Banei, Contai, Pathar Pratima Island
31 May & 12 Jul Bhogat, Bhanvad, Gondal, Gadhada, Amod, Nasvadi, Barwani, Birsa, Kawardha, Champa, Joda, Baripada, Nandigram
1 Jun & 11 Jul Bhatiya, Kamlapur, Sarangpur, Dabhoi, Kasrawad, Sanawad, Chhindwara, Seoni, Mungeli, Bilaspur, Sundargarh, Barbil, Manda, Beida, Haldia, Devasora South
2 Jun & 10 Jul Dwarka, Rajkot, Dholera, Vadodara, Bodeli, Manawar, Sukhtara, Pandaria, Rourkela, Baharagora, Tamluk, Phura
3 Jun & 9 Jul Motikhavdi, Dhandhuka, Borsad, Harda, Chhapara, Korna, Banki Mongra, Lailunga, Jorapokhar, Kharagpur, Medinipur, Debra, Baruipur, South Bungtlang, Kawichaw East
4 Jun & 8 Jul Jamnagar, Petlad, Tutugutu, Chaibasa, Kokpara, Jhargram, Bagnan, Maheshtala, Mothbari, Siaha
5 Jun & 7 Jul Dhrol, Wankaner, Thrangadh, Limbdi, Anand, Mhow, Itarsi, Lakhnadon, Mandla, Pathalgaon, Ghatshila, Howrah, Kolkata, Hasnabad, Chawngte P, Vaumbuk
6-10 Jun & 6-2 Jul Gandhidam, Morbi, Surendranagar, Dhrangadhra, Ahmedabad, Nadiad, Godhra, Dahod, Indore, Dewas, Hoshangabad, Narsingpur, Guthurma, Kunkuri, Jamshedpur, Dhaniakhali, Kalyani, Barrackpore, Bomgain, Basirhat, Lunglei, Lungsen
11-21 Jun & 2 Jul-21 Jun Kothara, Bhuj, Gandhinagar, Ratlam, Ujjain, Tarana, Bhopal, Jabalpur, Shahpura, Chirimiri, Ambikapur, Surajpur, Ranchi, Balarampur, Purulia, Bankura, Burdwan, Hanshkali, Thenzawl, Serchhip, Zokhawthar

You can also download this list as a pdf.

The apparent motion of the Sun in a year, leading to two equinoxes and solstices. © R.L. McNish

Download state-wise maps with the ZSDs marked

These maps are from Alok Mandavgane, with the dates overlaid on top.
Kerala, T.N. & Puducherry
Karnataka & Goa
Telengana & Andhra
Maharashtra
Gujarat, D&D, and D&H
M.P.
Chhattisgarh, Odisha, W.B., Jharkhand
Tripura & Mizoram
Andaman & Nicobar

Resource material on Zero Shadow Day

These resources have been shared by their creators under a non commercial Creative Commons License. If you would like to add your resource to this list, then contact us.

Articles

A page by Paranjpye on the ZSD and many easy ways of observing it (in English)

The ZSD page at the Jawarharlal Nehru Planetarium, Bengaluru

Information on the ZSD for Karnataka in Kannada, by the JNP

An article on the ZSD by R. Kavitha in Tamil

Videos

A video explaining the concept of Zero Shadow Day made by Arvind Gupta's Toys from Trash (in English)
The same video is also available A time-lapse video taken by Ajay Talwar from Dongla, near Ujjain
A time-lapse video taken by Arvind Paranjpye in Pune
and a news report of the ZSD public event organised by Jyotirvidya Parisanstha in Pune ...

Presentations

Listed below are presentations on ZSD that were created by astronomers and science popularisers. These are for public use (and with modifications if needed), but please do retain the title page that gives due credit to the authors. An introduction to ZSD by Dr. Priya Hasan (1.9 MB, English)

An introduction to ZSD by Rugved Pund of JVP (1.0 MB, English)

An introduction to ZSD by Dr. T.V. Venkateswaran (9.4 MB, English)

An activity guide for ZSD by Dr. T.V. Venkateswaran (0.7 MB, English)

An introduction to positional astronomy by Dr. T.V. Venkateswaran (2.8 MB, English)

An introduction to ZSD by Mr. Madivanane (8.8 MB, English)

ZSD training workshops

Workshops to train science popularisers and teachers are being organised in each state.

Regional

  1. 26 Mar 2017, Puducherry
    Workshop for science communicators from T.N., Kerala, Telengana, Andhra and Karnataka, organised in Puducherry by Vigyan Prasar, Puducherry Science Forum and POEC/ASI
  2. TBD
    A workshop for other states that will experience ZSD is being put together
States and districts

  1. 5-6 Apr 2017, Trivandrum, Kerala
    Workshop for science popularisers and teachers in Kerala, organised by KSSP, AASTRO and Trivandrum Planetarium
  2. 1 Apr 2017, Chennai, Tamilnadu
    Orientation camp for physics faculty, lab assistants and students in DG Vaishnav College
  3. 6 Apr 2017, Kerala
    AASTRO used the non-zero shadows at Kasargode and Trivandrum to measure the radius of the Earth, following Erastothenes, and obtained a value of 7000 km!
  4. 7 Apr 2017, Pudukottai, Tamilndadu
    ZSD camp organised in Panchayat Union School, Asoknagar, in Pudukottai by TNSF
  5. 8 Apr 2017, Chennai, Tamilndadu
    Orientation camp organised for 80 students and 10 teachers at KRM School by TNSF
  6. 9 Apr 2017, Trichy, Tamilnadu
    Workshop in Trichy for 32 school and college teachers and students from 5 central districts, organised by TNSF
  7. 9 Apr 2017, Tiruppur, Tamilnadu
    Workshop for 35 college students and TNSF volunteers from 5 western districts, organised by TNSF
  8. 13 Apr 2017, Kollam, Kerala
    Workshop for 35 students, organised by KSSP
  9. 14 Apr 2017, Coimbatore, Tamilnadu
    Orientation session following telescope making workshop for 25 members of VIPNET science club, organised by Vigyan Prasar
  10. 15 Apr 2017, Cumbum, Tamilnadu
    Workshop organised by TNSF
  11. 15 Apr 2017, Coimbatore
    Training and planning workshop organised by Galileo Science Club (VIPNET)
  12. 15 Apr 2017, Udumalpet
    Training and planning workshop organised by Galileo Science Club (VIPNET) for 65 school teachers
  13. 16 Apr 2017, Puducherry
    Workshop organised by Puducherry Science Forum for 35 science communicators from the state
  14. 16 Apr 2017, Chennai, Tamilnadu
    Workshop organised by TNSF for 25 science communicators from 3 districts
  15. 17 Apr 2017, Kozhikode, Kerala
    Workshop organised by KSSP
  16. 17 Apr 2017, Perinthalmanna, Kerala
    Workshop organised by KSSP for science communicators from Malappuram district
  17. 18 Apr 2017, Mysore, Karnataka
    Workshop organised by Mysore Science Foundation (VIPNET) at Sharada Vilas College of teacher education

ZSD public events

If you are planning to organise a public event for people to observe the Zero Shadow Day, let us know and we will include it here ...

  • 17 Apr 2017, Trichy, Tamilnadu
    Public event at three schools in Trichy for 500 students and 25 teachers, organised by TNSF
  • 17 Apr 2017, Udumalpet, Tamilnadu
    Public event at Panchayat Union Primary School, Ragalbavi for 50 students
  • 17 Apr 2017, Trichy, Tamilnadu
    Public event at Bharathi Matric. High School, organised by the school with TNSF. More details here
  • 21 Apr 2017, Puducherry State
    Public events organised at 15 places by Puducherry Science Forum, at
    • Raman Nagar, Lawspet
    • Sudhaana Nagar, Murungapakkam
    • Saram, Puducherry
    • Satya Special School, ECR Road, KAruvadikuppam
    • IG Girls High School Katterikuppam
    • SNG Girls High School, Puducherry
    • APJ SC & Planetarium, Lawspet
    • Udhavi Karangal, Nonankuppam
    • Kasthuri Bai Girls Higher Secondary School, Bahour
    • Kuruvinatham, Bahour
    • Girls High School Pandasozhanallur
    • Girls High School Manapet
    • Pondicherry Universotym Kalapet
    • Amalorpavam HSS
    • Dhanvantari Nagar, JIPMER Campus
    • Maraimalai Adigal Girls HSS, Embalam
    • ASN GMS Mudaliarpet

  • 21 Apr 2017, Mysore, Karnataka
    Public event at Gopalswamy College, Nanjumalige
  • 25 Apr 2017, Bengaluru, Karnataka
    Public event at Jawaharlal Nehru Planetarium, Bengaluru
  • 25 Apr 2017, Tumakuru, Karnataka
    Science Teachers Evaluation Centre, Tumakuru
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