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Indian Express
14-05-2025
- Science
- Indian Express
Daily subject-wise quiz : Science and Technology MCQs on Zero Shadow Day, tumour marker test and more (Week 110)
UPSC Essentials brings to you its initiative of subject-wise quizzes. These quizzes are designed to help you revise some of the most important topics from the static part of the syllabus. Attempt today's subject quiz on Science and Technology to check your progress. 🚨 Click Here to read the UPSC Essentials magazine for April 2025. Share your views and suggestions in the comment box or at Consider the following statements about Zero Shadow Day: 1. It occurs when the Sun's declination—its angular distance north or south of the celestial equator—matches the latitude of a particular location. 2. It occurs thrice a year in regions situated between the Tropic of Cancer and the Equator Which of the statements given above is/are correct? (a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2 Explanation — Several regions in West Bengal will witness the rare and scientifically significant phenomena known as Zero Shadow Day (ZSD) this year in June and July. — This astronomical occurrence occurs twice a year in places between the Tropic of Cancer and the Equator, when the Sun is directly overhead at local noon, allowing objects to cast no shadows for a brief duration. Hence, statement 2 is not correct. — Zero Shadow Day happens when the Sun's declination (angular distance north or south of the celestial equator) corresponds to the latitude of a certain location. Hence, statement 1 is correct. — At that same instant, the Sun reaches its greatest position in the sky, straight overhead, casting no visible shadow on upright objects. The effect is most visible for a few minutes at solar noon, when the Sun crosses the local meridian. Therefore, option (a) is the correct answer. The monographs (related to upper atmosphere) are the instruments which measure: 1. Pressure 2. Temperature 3. Relative humidity Select the correct answer using the codes given below: (a) 1 and 2 only (b) 2 only (c) 3 only (d) 1, 2 and 3 Explanation — In the wake of budget cuts by the Trump administration, a Silicon Valley startup will soon start to replace the National Oceanic and Atmospheric Administration's (NOAA's) weather balloons with AI-powered alternatives, which are supposed to be much cheaper. — Weather balloons are used by weather agencies all around the world to collect upper air measurements, which are critical for forecasting. Upper air refers to the Earth's atmosphere above 5,000 feet, from which the globe receives rain and drought, wind and stillness, heat and cold at its surface. — The practice of making upper-air observations dates back to the 18th century. It all started in 1749, when two students from Glasgow, Scotland, used kites to record temperature at great altitudes. Meteorologists began to deploy kites into the high atmosphere carrying aloft sensors known as monographs, which measured pressure, temperature, and relative humidity. Therefore, option (d) is the correct answer. With reference to the microalgae, consider the following statements: 1. They are microscopic algae with high chlorophyll content that lack lignin and cellulose but contain proteins. 2. They are primarily found in freshwater. 3. It can be used to treat industrial wastewater. 4. It can recycle CO2 to O2 while providing nourishment. How many of the statements given above are correct? (a) Only one (b) Only two (c) Only three (d) All four Explanation — Microalgae are known to grow quicker in microgravity environments and can recycle CO2 to O2 while producing nourishment. Hence, statement 4 is correct. — Microalgae are microscopic algae with high chlorophyll content that lack lignin and cellulose but contain proteins. Hence, statement 1 is correct. — Microalgae are primarily found in freshwater and marine ecosystems. Hence, statement 2 is correct. — Microalgae can be successfully used to treat industrial wastewater. According to the researchers, as the microorganisms feed, they expand and reproduce, offering a wealth of algae-based biomass for the production of bioenergy, high-value bio-based chemicals, and speciality items. Hence, statement 3 is correct. Therefore, option (d) is the correct answer. The Indian Space Research Organisation (ISRO) inked a Joint Statement of Intent on Human Space Exploration on the sidelines of the Global Space Exploration Conference (GLEX) – 2025 with: (a) European Space Agency (ESA) (b) National Aeronautics and Space Administration (NASA) (c) Japan Aerospace Exploration Agency (JAXA) (d) Roscosmos Explanation — The European Space Agency (ESA) now has direct and clearer objectives for working with India, and it is willing to collaborate on larger and undiscovered areas of space, according to Dr Josef Aschbacher, the ESA director general. — The Indian Space Research Organisation (ISRO) and the European Space Agency (ESA) signed a Joint Statement of Intent on Human Space Exploration on the margins of the Global Space Exploration Conference (GLEX) 2025. — ESA is pleased to collaborate with ISRO and looks forward to investigating large-scale space activities. It is a significant honour for ESA and ISRO to collaborate in the field of space exploration. — Collaborations are being considered for India's projected Bharatiya Antariksha Station (BAS). India intends to build the space station by 2035. The BAS-1, which has five modules, is expected to launch in 2028. Therefore, option (a) is the correct answer. With reference to the tumour marker test, consider the following statements: 1. A tumour marker test measures the number of substances called tumour markers in tissue, blood, urine, or other body fluids. 2. Most tumour markers are proteins made by both normal cells and cancer cells, but they are made in higher amounts by normal cells. Which of the statements given above is/are correct? (a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2 Explanation — A tumour marker test, according to the National Cancer Institute, counts the number of chemicals known as tumour markers in tissue, blood, urine, or other body fluid. Hence, statement 1 is correct. — 'The majority of tumour markers are proteins produced by both normal and cancer cells, but cancer cells produce more of them. Genetic changes in cancer tissue, including as gene mutations, gene expression patterns, and other DNA modifications, are also utilised as tumour indicators. Hence, statement 2 is not correct. — Tumour marker tests include Prostate-specific antigen (PSA), Prostatic acid phosphatase (PAP), CA 125, Carcinoembryonic antigen (CEA), Alpha-fetoprotein (AFP), CA 19-9, CA 15-3, CA 27-29, Lactate dehydrogenase (LDH), and bladder tumour marker investigations. Therefore, option (a) is the correct answer. Daily Subject-wise quiz — History, Culture, and Social Issues (Week 109 and 110) Daily subject-wise quiz — Polity and Governance (Week 110) Daily subject-wise quiz — Science and Technology (Week 109) Daily subject-wise quiz — Economy (Week 109) Daily subject-wise quiz — Environment and Geography (Week 109) Daily subject-wise quiz – International Relations (Week 109) Subscribe to our UPSC newsletter and stay updated with the news cues from the past week. Stay updated with the latest UPSC articles by joining our Telegram channel – IndianExpress UPSC Hub, and follow us on Instagram and X.
Indian Express
14-05-2025
- Science
- Indian Express
When and where you can observe ‘zero shadow day' in Bengal
Written by Adrija Datta Several districts across West Bengal are set to witness the rare and scientifically significant phenomenon of Zero Shadow Day (ZSD) during the months of June and July this year. 'In Kolkata, Zero Shadow will occur on June 5 and July 7,' said Debapriya Roy, Head of Positional Astronomy Centre of Kolkata. This astronomical event, which occurs twice a year in regions situated between the Tropic of Cancer and the Equator, takes place when the Sun is positioned directly overhead at local noon, causing objects to cast no shadow for a brief period. In 2025, the Zero Shadow phenomenon will be observed in multiple districts of the state, including Kolkata, Howrah, Hooghly, Nadia, Medinipur, Bankura, and Purulia. According to the Astronomical Society of India, the scheduled dates and times for these districts are as follows: Kolkata: June 5 at 11:35 am and July 7 at 11:41 am Howrah: June 5 at 11:35 am and July 7 at 11:42 am Hooghly: June 8 at 11:35 am and July 4 at 11:41 am Nadia: June 6 at 11:33 am and July 6 at 11:40 am Medinipur: June 4 at 11:39 am and July 9 at 11:46 am Bankura: June 13 at 11:42 am and June 30 at 11:45 am Purulia: June 15 at 11:45 am and June 27 at 11:48 am Zero Shadow Day occurs when the Sun's declination—its angular distance north or south of the celestial equator—matches the latitude of a particular location. At that exact moment, the Sun reaches its highest point in the sky directly overhead, eliminating any visible shadow for upright objects. The effect is most noticeable for a few minutes around solar noon, when the Sun crosses the local meridian. 'Members of our association will be carrying out individual experiments involving vertical objects on this day and will document their observations through photographs. The results of these experiments will later be shared on our social media platforms for public viewing.' said Dipankar Dey of the Sky Watchers Association of Kolkata. This phenomenon is only experienced in the tropical zone, which lies between the Tropic of Cancer (23.5°N) and the Tropic of Capricorn (23.5°S). Though the event has no direct meteorological impact, ZSD serves as an observable demonstration of Earth's tilt and orbital motion, reinforcing fundamental principles of geography and astronomy. Adrija Datta is an intern with the Indian Express
Time of India
11-05-2025
- Science
- Time of India
Kolkata, other Bengal cities to experience Zero Shadow Days; check dates, timings, and locations
KOLKATA: Residents of Kolkata and several other cities across Bengal will have a rare opportunity to witness a unique astronomical event twice in 2025 — the Zero Shadow Day (ZSD) — when vertical objects will cast no shadow at all for a brief moment around noon. In Kolkata, this phenomenon will occur on June 5 at 11:34:54am and again on July 7 at 11:41:24 am (IST). Zero Shadow Day occurs twice a year for locations situated between the Tropic of Cancer (23.5° N) and the Tropic of Capricorn (23.5° S) — the tropical zone of the Earth. On these days, the Sun is exactly overhead at noon, causing vertical objects, including humans, to cast no visible shadow for a few moments. This happens because the Sun's declination (its apparent latitude in the sky) aligns perfectly with the geographic latitude of the location, said Bipas Das Gupta, Scientific Officer, M. Operation Sindoor Amid flare-up hours after thaw, officials say things will settle down with time Ceasefire on, but pressure stays: Key decisions by India against Pak that still stand 'Will work with India & Pakistan to seek solution on Kashmir': Trump P. Birla Institute of Fundamental Research. At that moment, the Sun is at the zenith, the highest point in the sky directly above an observer. Due to the Sun's angular diameter of about half a degree, this phenomenon is observable for around 1 to 1.5 minutes, though viewers are advised to be ready at least 30 minutes before and after the scheduled time. Apart from its visual appeal and educational value, Zero Shadow Day provides a hands-on opportunity to explore key astronomical concepts such as Earth's rotation, seasonal changes, solar declination, and the geometry of sunlight. The event also mirrors how the ancient Greek scholar Eratosthenes famously estimated the Earth's circumference using shadow lengths in different cities. Zero Shadow Days provide a fascinating link to Earth's position and motion in space. The Sun's apparent movement — northward during Uttarayan (January to June) and southward during Dakshinayan (July to December) — causes the Sun to be overhead at different places throughout the year. ZSD occurs when the Sun's declination equals a location's latitude, which is why people in the tropics experience this twice annually, while those outside this zone never do. The Tropic of Cancer — at latitude 23° 26' N — passes through Krishnanagar in West Bengal, one of only eight Indian states where this happens. Others include Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, Tripura, and Mizoram. Zero Shadow Days Across West Bengal in 2025: The dates and timings for key Bengal cities (all times in IST): Kolkata: June 5, 11:34:54 am ; July 7, 11:41:24 am Bardhaman: June 14, 11:38:44 am ; June 28, 11:41:45 am Kharagpur: June 3, 11:38:52 am ; July 9, 11:45:58 am Mayapur: June 19, 11:37:53 am ; June 23, 11:38:45 am Diamond Harbour: June 2, 11:35:10 am ; July 10, 11:42:34 am Krishnanagar: June 17, 11:36:58 am ; June 25, 11:38:43 am Haldia: June 1, 11:35:29 am ; July 11, 11:43:10 am Midnapur: June 4, 11:39:17 am ; July 8, 11:45:53 am Barrackpur: June 7, 11:35:19 am ; July 5, 11:41:04 am Baruipur: June 3, 11:34:24 am ; July 9, 11:41:30 am Digha: May 29, 11:37:10 am ; July 14, 11:45:39 am Purulia: June 16, 11:45:14 am ; June 27, 11:47:36 am Kalyani: June 10, 11:35:38 am ; July 2, 11:40:16 am Habra: June 8, 11:34:35 am ; July 4, 11:39:58 am Get the latest lifestyle updates on Times of India, along with Mother's Day wishes , messages , and quotes !
The Hindu
22-04-2025
- Science
- The Hindu
‘Zero Shadow Day' observed in Mysuru
The Cosmology Education and Research Training Center (COSMOS), Mysuru, of the Indian Institute of Astrophysics on Tuesday observed 'Zero Shadow Day' at Vignana Bhavan, Manasagangotri here. Amoghavarsha N., Project Associate of COSMOS, IIA, delivered a lecture on the science behind Zero Shadow Day. Later, hands-on experiments and demonstrations were shown to participants by the SCOPE Team of IIA, led by Vikranth Pulamathi. Participants were asked to take readings of the length of the shadow made by the Gnomons (Shanku Yantra) every five minutes from 11.45 a.m. to 1.00 p.m. to note down changes in the shadow. Zero shadow phenomenon was observed at 12.22 p.m., demonstrated by a hollow cylinder on a glass plate along with the Gnomons, according to COSMOS. Yashaswini K.S. and Renjithmon A.A. of IIA showed the sunspots to the participants. The event concluded with participants calculating the declination of the sun, finding the true north, and noting down the zero shadow phenomena, followed by a question and answer session. Zero Shadow Day (ZSD) occurs when the sun is directly overhead (i.e., at the zenith). At this moment, any object held vertically will not cast any shadow on the ground, since the sun's rays fall straight down on it, rather than at an angle. On other days, the sun is not exactly overhead at noon, a press release from COSMOS explained. 'Only locations lying between the Tropic of Cancer and the Tropic of Capricorn will experience ZSD, which will occur twice a year, corresponding to the northern and southern movements. Since the Earth is tilted on its axis by about 23.5 degrees, as it revolves around the sun, the sun can pass overhead only for locations whose latitude lies between 23.5° N and 23.5° S. Hence, different locations experience ZSD on different days. ZSD for Mysuru is on April 22 and August 19,' the organisation said.
The Hindu
21-04-2025
- Science
- The Hindu
Zero Shadow Day observed across schools
Scores of school students observed Zero Shadow Day (ZSD) at their campuses under the auspices of the Directorate of School Education and the Pondicherry Science Forum. According to a press note from the Forum, the phenomeon was observable in the city between 10 a.m and 12.30 p.m. with the aid of instruments installed across schools. The ZSD marks the bi-annual phenomena when the sun's declination perfectly corresponds to the latitude of a location on earth. When the sun is at is zenith, at 12.10 p.m., it creates a zero shadow effect. This year, the day was observed across 218 urban/rural schools and teachers were specially trained to explain the phenomenon to students as part of an initiative of the Samagra Shiksha programme of the Education Department. Representatives of the Forum, including A. Hemavathi, R. Madivanan and S. Muruguvel and school officials coordinated the programme.
