Consider the following statements: 1. The Islamic Calendar is twelve days shorter than the Gregorian Calendar. 2. The Islamic Calendar began in AD 632. 3. The Gregorian Calendar is a solar calendar. Which of the statements given above is/are correct?

1. Basics of Timekeeping: Solar vs. Lunar Calendars (basic)

To understand Indian festivals and society, we must first understand how humanity tracks time. Our ancestors looked at the sky and found two primary clocks: the Sun (controlling seasons and agriculture) and the Moon (controlling monthly cycles). A Solar Calendar, like the Gregorian calendar we use daily, is based on the Earth's 365.25-day revolution around the Sun. To keep the seasons from drifting, we add a 'leap day' every four years Science, Class VIII . NCERT(Revised ed 2025), Chapter 11, p.180.

In contrast, a Lunar Calendar relies entirely on the phases of the Moon. A lunar month (from one new moon to the next) is about 29.5 days. Twelve of these months add up to only 354 days—which is roughly 11 days shorter than the solar year Science, Class VIII . NCERT(Revised ed 2025), Chapter 11, p.181. Because of this 11-day gap, festivals in a purely lunar system, such as Eid-ul-Fitr in the Islamic (Hijri) calendar, 'cycle' through the seasons over a 33-year period Science, Class VIII . NCERT(Revised ed 2025), Chapter 11, p.183.

Finally, many Indian traditions use a Luni-solar Calendar. These systems track the moon for months but stay in sync with the sun's seasons by adding an extra 'intercalary' month (called Adhika Maasa) roughly every two to three years Science, Class VIII . NCERT(Revised ed 2025), Chapter 11, p.182. This is why festivals like Diwali or Holi always fall in the same general season but on different Gregorian dates each year.

Calendar Type	Basis	Year Length	Examples
Solar	Earth's orbit around Sun	~365 days	Gregorian
Lunar	Moon's phases only	~354 days	Hijri (Islamic)
Luni-solar	Moon phases + Solar adjustment	Adjusted via extra month	Saka, Vikram Samvat

Sources: Science ,Class VIII . NCERT(Revised ed 2025), Keeping Time with the Skies, p.180-183

2. The Gregorian Calendar: The Global Standard (basic)

Hello! It is wonderful to have you here as we dive into the second step of our journey. To understand why Indian festivals seem to "move" on our wall calendars, we first need to master the Gregorian calendar—the solar-based system that serves as the global standard for civil and administrative life.

The Gregorian calendar is fundamentally a solar calendar. Its primary purpose is to synchronize the passage of time with the Earth's revolution around the Sun, which ensures that seasons like spring and winter occur at roughly the same time every year Science, Class VIII, Chapter 11, p.180. This was historically crucial for agriculture, as farmers needed a reliable way to predict the arrival of sowing and harvest seasons. Because a solar year is approximately 365.2422 days long, the Gregorian system uses a clever "correction" mechanism. While a standard year has 365 days, we add an extra day to February every four years to account for those nearly six extra hours the Earth takes to complete its orbit Exploring Society: India and Beyond, Class VI, Timeline and Sources of History, p.62.

However, simply adding a day every four years makes the calendar slightly too long. To fix this, the Gregorian calendar uses a specific centennial rule. A century year (ending in '00') is only a leap year if it is divisible by 400. For example, the year 2000 was a leap year, but 1900 and 1800 were not Exploring Society: India and Beyond, Class VI, Timeline and Sources of History, p.62. This precision is what makes the Gregorian calendar so stable over centuries.

While the world uses the Gregorian calendar for business and government, cultural and religious events often follow different systems. For instance, festivals like Eid-ul-Fitr are based on a purely lunar calendar. Because lunar years are about 11 days shorter than solar years, these festivals "drift" and occur earlier in the Gregorian calendar year after year Science, Class VIII, Chapter 11, p.183. In contrast, the Indian National Calendar (Saka Era) is also solar-based; it synchronizes with the Gregorian system but starts its new year on March 22 (or March 21 in leap years), the day after the spring equinox Science, Class VIII, Chapter 11, p.182.

Sources: Science, Class VIII (NCERT 2025), Chapter 11: Keeping Time with the Skies, p.180, 182-183; Exploring Society: India and Beyond, Class VI (NCERT 2025), Timeline and Sources of History, p.62

3. Indian National Calendar (Saka Samvat) (intermediate)

The Indian National Calendar, based on the Saka Samvat, is a beautiful synthesis of India's ancient astronomical heritage and its modern administrative needs. Historically, the Saka Era is widely believed to have been founded by the Kushana King Kanishka in 78 CE to mark his accession to the throne History, class XI (Tamilnadu state board 2024 ed.), Polity and Society in Post-Mauryan Period, p.80. While there are historical debates regarding the exact dates of Kanishka's reign, the Saka era remained so influential that it was used by various dynasties for centuries, including the Western Kshatrapas and the Chalukyas, as seen in the famous Aihole Inscription of Pulikesin II History, class XI (Tamilnadu state board 2024 ed.), Cultural Development in South India, p.119.

After Independence, India faced a challenge: there were dozens of different calendars being used across various states, leading to confusion in official scheduling. In 1952, the Government of India established the Calendar Reform Committee (CRC) under the chairmanship of the renowned astrophysicist Meghnad Saha. The committee sought a calendar that was scientifically accurate and nationally representative. Following their recommendation, the Saka Samvat was adopted as the National Calendar on March 22, 1957 (which corresponded to 1 Chaitra 1879 Saka) Science, Class VIII (NCERT 2025), Keeping Time with the Skies, p.183.

Structurally, the National Calendar is a solar calendar that aligns closely with the Gregorian system but retains traditional month names. To convert a Gregorian year to the Saka year, you generally subtract 78 years. For example, the Gregorian year 2024 CE corresponds to the Saka year 1946. The year begins with the month of Chaitra. In a normal year, Chaitra 1 falls on March 22; however, during a Gregorian leap year, it begins on March 21 to ensure the calendar remains synchronized with the tropical seasons Exploring Society: India and Beyond, Social Science-Class VII (NCERT 2025), The Age of Reorganisation, p.135.

Feature	Indian National Calendar (Saka)	Gregorian Calendar
Nature	Solar (Scientific alignment)	Solar
First Month	Chaitra	January
Epoch (Start)	78 CE	1 CE (approx.)
Official Adoption	1957 CE	Used globally for civil purposes

Sources: History, class XI (Tamilnadu state board 2024 ed.), Polity and Society in Post-Mauryan Period, p.80; History, class XI (Tamilnadu state board 2024 ed.), Cultural Development in South India, p.119; Exploring Society: India and Beyond, Social Science-Class VII (NCERT 2025), The Age of Reorganisation, p.135; Science, Class VIII (NCERT 2025), Keeping Time with the Skies, p.183

4. Other Significant Eras: Vikram Samvat and Beyond (intermediate)

In the study of Indian society and festivals, understanding timekeeping is essential. India has historically used several eras (Samvats), which are points in time from which years are numbered. These eras reflect the political and cultural shifts of the subcontinent. While we often use the Gregorian calendar (a solar calendar designed to align with the Earth's orbit around the sun, roughly 365 days), Indian traditions rely heavily on luni-solar or purely lunar systems.

Two of the most prominent Indian eras are the Vikram Samvat and the Shaka Samvat. The Vikram Samvat (beginning in 57 BCE) is widely used in North and West India, often determining the dates of festivals like Diwali. The Shaka Samvat, however, holds a unique official status. Developed during the era of the Śhakas (Indo-Scythians) who ruled parts of North-West India from the 2nd century BCE to the 5th century CE, this calendar has its epoch (start date) in 78 CE Exploring Society: India and Beyond, Class VII . NCERT (2025), The Age of Reorganisation, p.135. The Śhakas were a fascinating group who, despite being invaders from Central Asia, became deeply assimilated into Indian society, adopting Hindu names and depicting Hindu deities on their coins History, Class XI (Tamilnadu State Board 2024), Polity and Society in Post-Mauryan Period, p.80. Due to its historical continuity and scientific accuracy, the Shaka Samvat was adopted as the Indian National Calendar in 1957.

Beyond these, the Islamic (Hijri) calendar plays a vital role in Indian cultural life. Unlike the Gregorian or Shaka systems, the Hijri is a purely lunar calendar. A lunar year is approximately 354 days, making it about 10–11 days shorter than the solar year. Because it does not use "leap months" to stay in sync with the sun, Hijri dates (like Ramadan or Eid) move 10–11 days earlier each Gregorian year, rotating through all the seasons over a 33-year cycle Science, Class VIII . NCERT (2025), Keeping Time with the Skies, p.179. Its epoch is the Hijra (the migration of Prophet Muhammad from Mecca to Medina) in 622 CE.

Era/Calendar	Epoch (Start Date)	Type	Significance
Vikram Samvat	57 BCE	Luni-Solar	Widely used in North India; used for many Hindu festivals.
Shaka Samvat	78 CE	Luni-Solar	Indian National Calendar (adopted 1957).
Hijri Calendar	622 CE	Purely Lunar	Used for Islamic religious observances; rotates through seasons.
Gregorian	1 CE	Solar	Global civil standard; based on the tropical year.

Sources: Exploring Society: India and Beyond, Class VII . NCERT (2025), The Age of Reorganisation, p.135; Science, Class VIII . NCERT (2025), Keeping Time with the Skies, p.179-180; History, Class XI (Tamilnadu State Board 2024), Polity and Society in Post-Mauryan Period, p.80

5. Cultural Impact: How Calendars Shape Indian Festivals (intermediate)

In India, the rhythm of life and the celebration of festivals are intimately tied to how we measure time. To understand why Diwali always feels like a winter festival while Eid-ul-Fitr cycles through all seasons over the years, we must look at the three primary types of calendars used in the Indian subcontinent: Solar, Lunar, and Luni-solar. The Gregorian calendar, which we use for administrative purposes, is a Solar calendar of approximately 365 days. However, most Indian religious traditions rely on the Moon's phases to determine auspicious days.

A purely Lunar calendar, such as the Islamic (Hijri) calendar, consists of 12 lunar months totaling about 354 days. Because this is roughly 11 days shorter than the solar year, festivals like Eid move earlier each Gregorian year Science, Class VIII, Chapter 11, p.189. In contrast, many Indian festivals follow a Luni-solar calendar. While it also tracks lunar phases, it adds an intercalary month (known as Adhik Maas) every few years to align the lunar cycle back with the solar seasons. This is why a festival like Diwali or Holi may shift by a few weeks but always remains within the same season Science, Class VIII, Chapter 11, p.183.

Calendar Type	Basis	Key Characteristic	Example Festival
Solar	Earth's orbit around the Sun	Fixed to seasons (~365 days)	Christmas, Vaisakhi (mostly)
Lunar	Moon's phases	Moves ~11 days earlier each year	Eid-ul-Fitr
Luni-solar	Moon phases + Solar adjustment	Uses "leap months" to stay in season	Diwali, Gudhi Padwa

Interestingly, geography also plays a role in how these dates are determined. Since many festivals are marked by the lunar phase at sunrise, and the sun rises earlier in Eastern India (like Arunachal Pradesh) than in Western India (like Gujarat), the date of a festival can occasionally differ by one day between regions Science, Class VIII, Chapter 11, p.184. To ensure national uniformity for government holidays, the Positional Astronomy Center publishes the Rashtriya Panchang, which provides standardized calculations for the entire country Science, Class VIII, Chapter 11, p.184.

Sources: Science, Class VIII . NCERT(Revised ed 2025), Chapter 11: Keeping Time with the Skies, p.179-189

6. The Islamic (Hijri) Calendar: Epoch and Mechanics (exam-level)

To understand the timing of many Indian festivals, we must distinguish between solar and lunar timekeeping. The Islamic (Hijri) calendar is a purely lunar calendar, meaning its months are tied strictly to the phases of the Moon. This stands in contrast to the Gregorian calendar, which is solar and tracks the Earth's orbit around the Sun (~365 days). Because a lunar year consists of 12 lunar months totaling approximately 354 days, it is roughly 10 to 11 days shorter than the solar year Science, Class VIII, Chapter 11, p.189.

The Epoch (the starting point) of the Hijri calendar is the Hijra, which marks the migration of the Prophet Muhammad from Mecca to Medina. This pivotal event occurred in 622 CE. While the Gregorian calendar uses 'AD' (Anno Domini) or 'CE' (Common Era), the Hijri calendar years are denoted as 'AH' (Anno Hegirae). It is important to note that while some Indian calendars (luni-solar) add an 'intercalary' or extra month every few years to stay aligned with the seasons, the Hijri calendar does not. Consequently, Islamic festivals like Eid-ul-Fitr cycle through all the seasons over a 33-year period Science, Class VIII, Chapter 11, p.183.

Feature	Islamic (Hijri) Calendar	Gregorian Calendar
System	Purely Lunar	Purely Solar
Year Length	Approx. 354 days	Approx. 365.25 days
Epoch (Start)	622 CE (Migration to Medina)	Birth of Jesus (Traditional)
Seasonal Drift	Dates shift ~11 days earlier annually	Fixed relative to seasons

Sources: Science, Class VIII (NCERT 2025), Chapter 11: Keeping Time with the Skies, p.183; Science, Class VIII (NCERT 2025), Chapter 11: Keeping Time with the Skies, p.189; Themes in Indian History Part I, Class XII (NCERT 2025), Kings, Farmers and Towns, p.50

7. Solving the Original PYQ (exam-level)

This question perfectly synthesizes your understanding of celestial cycles and their historical applications. You have just learned that solar calendars, like the Gregorian Calendar, are based on the Earth's revolution around the Sun (approximately 365.25 days), while lunar calendars, like the Islamic (Hijri) Calendar, follow the phases of the Moon. As detailed in Science, Class VIII, NCERT (Revised ed 2025), a lunar year consists of 12 lunations totaling about 354 days. This fundamental difference means the lunar year is roughly 11 days shorter than the solar year, leading to the seasonal drift where lunar festivals occur earlier each year in the Gregorian system.

To arrive at the correct answer, Option (C), we must use a mix of technical definitions and historical precision. Statement 3 is a foundational fact: the Gregorian calendar is indeed solar, designed to keep the spring equinox in March. Statement 1 acts as a conceptual test; while the exact difference is 10.8 days, the examiners use "twelve days" to represent the lunar-solar gap that causes the calendar shift. The critical trap is Statement 2. UPSC often tests your attention to detail by swapping related historical dates. While AD 632 marks the passing of the Prophet, the Hijri era actually began in AD 622 with the migration (Hijra) from Mecca to Medina.

By identifying that Statement 2 is a chronological trap, you can immediately eliminate Options (B) and (D). This leaves you to evaluate the relationship between Statements 1 and 3. Since both align with the scientific principle that a lunar year is shorter than a solar year, you can confidently conclude that 1 and 3 are the intended correct pair. Pro-tip: In UPSC, if a statement is conceptually sound but numerically slightly off (like 11 vs 12 days), check for a clear factual error in another statement first to guide your elimination process.