Zero Shadow Day

With an Axial tilt of 23.5° and moving around the Sun, the appears to move towards the north and south giving us Solstice and Equinox. As the Sun oscillates in the sky between the Tropic of Capricorn and the Tropic of Cancer, twice a year (except for the equator), all places between these two latitudes, experience Zero Shadow Day.

Zero Shadow?

Shadows are created as a consequence of the light from a source being blocked by an object onto the screen. Now imagine the Sun being the source, you being the object and the ground being the screen. As the sun moves up vertically in the sky, our shadows are cast onto the ground with the our foot connected to the foot of the shadow . As the sun moves, the shadow moves too and as the sun set, our shadow disappears.

Now what if the Sun was shining directly above our head? Well, you guessed it right. Our shadow would be below us and hence not visible (unless you can see through yourself).

Why does it not happen every day?

The sun moves up in the sky and at noon, we know the sun is above us. But the sun is not exactly above us every day. In astronomy “Zenith” is an imaginary point directly “above” a particular location, or if you stand on the ground and look up (perpendicular to the ground) you would be looking at the Zenith. And for the Sun to cast a shadow right below you, it would have to pass through Zenith. On any given day, around noon, the sun is slightly to the left or right therefore it will still cast a shadow, though a small one.

But there are two days in a year when (depending upon your location) the Sun is exactly at Zenith and would cast NO Shadow!

How Can I “Not See” the Shadows?

Yes of course! PAAC urges all of you to verify this and enjoy the astronomical phenomenon.

As you have noted, the ZSD appears twice a year, but due to the nature of rainy season, the August dates will mostly likely be cloudy. So this is your Chance! So, here’s what you could do and enjoy on that day.

There is certain period of time in which this event happens. So make sure the time at which it happens in your region and at that time :

Experiment 1: Self Shadow

Go out to the in the open (terrace or front yard of your house) and look for your shadow, standing straight.
You will notice very little or no shadow. Most of the shadow that you see will be of your head leaning forward.
- If you do observe your body’s shadow it will be minimal and it exists because your foot is narrower than your torso and what you are seeing is the shadow of your arms.
Try with another person. When that person stands straight, you can observe his/her shadow to be missing.
Jump up and notice how your shadow is still there, just that you are standing on it.

Experiment 2 : No Shadow

You’ve noticed how your shadow still exists because of your asymmetry (torso being wider than legs). Let’s eliminate this.
Take an object whose width does not change with height. Like a cylinder. Works better if the object’s width reduces with height, like a cone. We recommend a narrow cylinder or a Cone as to observe the exact moment more clearly.
Start a few mins before the Zero Shadow Time. As the Sun rises in the sky, you will notice the shadow of the object gets smaller and smaller. When the Sun passes through the Zenith, the shadow will take a break and not be visible.

So, don’t miss the chance of celebrating this wonderful , astonishing astronomical event.

If you want to find out the ZSD for your location check out ZSD App on Google Play Store

Astronomical Society of India has a page on Zero Shadow Day with a lot of resources, maps and experiments mentioned too.

Here’s a list of places with their Zero Shadow Days in India. Only dates are given, Times vary with Longitudes.

Karnataka with Map

All India

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

Source: https://abhinavspaceindia.blogspot.com