RBSE Solutions Class 9 Science Chapter 12 Celestial Bodies and Indian Calendar

Celestial Bodies and Indian Calendar

Celestial Bodies and Indian Calendar Textbook Questions Solved

Objective Type Questions

 

Question 1. Celestial bodies which have their own light and heat are known as:
(A) Stars
(B) Planets
(C) Satellites
(D) Meteors
Answer: (A) Stars
In simple words: Stars are like giant, bright balls in space that make their own light and heat. Planets, satellites, and meteors do not produce their own light.

🎯 Exam Tip: Remember that stars generate energy through nuclear fusion, distinguishing them from other celestial bodies like planets or moons.

 

Question 2. Moon is categorised in which series of solar system?
(A) Star
(B) Planet
(C) Satellite
(D) Asteroid
Answer: (C) Satellite
In simple words: The Moon goes around the Earth, so it is called a natural satellite. It does not make its own light but reflects sunlight.

🎯 Exam Tip: Satellites, whether natural like the Moon or artificial, are objects that orbit around a larger celestial body.

 

Question 3. According to Indian Panchang, the number of Nakshatra are:
(A) 15
(B) 27
(C) 12
(D) 07
Answer: (B) 27
In simple words: In the Indian calendar system, there are 27 Nakshatras, which are specific parts of the sky used for astrological calculations. These divisions help track time and celestial positions.

🎯 Exam Tip: Nakshatras are crucial for understanding the Indian calendar and astrological timings, representing lunar mansions.

 

Question 4. According to Indian Panchang the number of Rashis are:
(A) 15
(C) 12
Answer: Not provided in source.
In simple words: The number of Rashis, or zodiac signs, in the Indian Panchang is typically understood to be 12. This system helps in understanding celestial positions and time.

🎯 Exam Tip: Rashis are equivalent to zodiac signs in Western astrology, each representing a specific division of the celestial sphere.

 

Question 6. Which is the largest planet in our Solar System:
(A) Jupiter
(B) Saturn
(C) Uranus
(D) Neptune
Answer: (A) Jupiter
In simple words: Jupiter is the biggest planet in our solar system, much larger than all the other planets combined. It is famous for its giant red spot.

🎯 Exam Tip: Knowing the order and relative sizes of planets is fundamental to understanding the solar system.

 

Question 7. After how many years did Adhik Mass occurs?
(A) After 1 year
(B) After 2 years
(C) After 3 years
(D) After 4 years
Answer: (C) After 3 years
In simple words: Adhik Mass, which is an extra month, happens about every three years in the Hindu calendar to keep the lunar and solar calendars aligned. This adjustment ensures that festivals and seasons stay in sync.

🎯 Exam Tip: Adhik Mass (or Purushottam Mass) is an important concept in the lunisolar Hindu calendar, balancing the solar and lunar year lengths.

 

Question 8. In which Rashi, Sun is located after starting of Dakshinayan?
(A) Cancer
(B) Leo
(C) Capricorn
(D) Aquarius
Answer: (A) Cancer
In simple words: When Dakshinayan begins, the Sun enters the Cancer zodiac sign. This marks the start of the Sun's southward journey in the sky.

🎯 Exam Tip: Understanding the Sun's movement through different Rashis (zodiac signs) is key to comprehending celestial phenomena like solstices and equinoxes in Indian astronomy.

Celestial Bodies and Indian Calendar Very Short Answer Type Questions

 

Question 10. The first Indian Satellite was named on which scientist?
Answer: The first Indian satellite was named Aryabhatta. This satellite was a tribute to the great ancient Indian mathematician and astronomer. Aryabhatta contributed greatly to mathematics and science.
In simple words: India's first satellite was named Aryabhatta, after a famous old Indian scientist.

🎯 Exam Tip: Remembering the names of important figures in Indian science and their contributions, like Aryabhatta's work in astronomy and mathematics, is helpful.

 

Question 11. Which the occurs after chaturdashi of Shukla paksh?
Answer: Panchami occurs after Chaturdashi of Shukla Paksh. This refers to the fifth day of the bright fortnight in the lunar calendar. It follows the fourteenth day (Chaturdashi).
In simple words: After the fourteenth day of the bright half of the lunar month (Chaturdashi), the fifth day (Panchami) comes.

🎯 Exam Tip: Familiarize yourself with the sequence of tithis (lunar days) and pakshas (fortnights) in the Hindu calendar.

 

Question 12. Name the Chandramass in which moon is at Mrigashira Nakshatra on Pumima.
Answer: The Chandramass in which the moon is at Mrigashira Nakshatra on Purnima is Marga Shirsh. This month is associated with the Mrigashira constellation during the full moon. Marga Shirsh is considered an auspicious month in the Hindu calendar.
In simple words: When there is a full moon in the Mrigashira constellation, the month is called Marga Shirsh.

🎯 Exam Tip: Connecting the names of Chandramass (lunar months) with the Nakshatra (constellation) during Purnima (full moon) is key to understanding the traditional calendar.

 

Question 13. Which planet has the least orbital time period?
Answer: Mercury has the least orbital time period. Its orbital time period is 88 days. Being the closest planet to the Sun, Mercury completes its orbit much faster than any other planet. This short period is due to its proximity to the Sun.
In simple words: Mercury goes around the Sun the fastest, taking only 88 days.

🎯 Exam Tip: Remember that the closer a planet is to the Sun, the faster it orbits, due to the stronger gravitational pull.

 

Question 14. Write the name of the planet in serial order on the basis of their distance from the Sun?
Answer: The planets in serial order based on their distance from the Sun are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. This order is commonly remembered using mnemonics to help students recall them easily. Each planet occupies a distinct orbit around our star, the Sun.
In simple words: The planets from closest to farthest from the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

🎯 Exam Tip: Learning a mnemonic (e.g., "My Very Eager Mother Just Served Us Noodles") can help you remember the order of planets from the Sun.

 

Question 15. Write the name of 'terrestrial planets'?
Answer: Terrestrial planets are Mercury, Venus, Earth, and Mars. These planets are known for their solid, rocky surfaces. They are relatively smaller and denser compared to the gas giants further out in the solar system.
In simple words: The rocky planets with solid ground are Mercury, Venus, Earth, and Mars.

🎯 Exam Tip: Distinguish between terrestrial (rocky) planets and gas giant planets based on their composition and location in the solar system.

 

Question 16. Life is discovered on which planet, except Earth?
Answer: Life, as we know it, has not been definitively discovered on any planet except Earth. While scientists are actively searching for signs of life on other celestial bodies, especially Mars and some moons in our solar system, Earth remains the only known planet to harbor life. This search involves looking for water, specific chemicals, and conditions that could support living organisms.
In simple words: So far, Earth is the only planet where life has been found. Scientists are still looking for life elsewhere.

🎯 Exam Tip: State the current scientific consensus clearly; while there's a search for extraterrestrial life, Earth is currently the only confirmed planet with life.

 

Question 18. Two Planets A and B are simultaneously a distance X and Y from Sun. If Y is greater than X, then which planet has the largest revolution time.
Answer: If planet Y is greater distance than X from the Sun, then planet Y has the larger revolution time. This is because planets further from the Sun have larger orbits and move slower. Kepler's laws of planetary motion explain this relationship between orbital distance and period. Therefore, a planet with a larger orbit will take more time to complete one revolution around the Sun.
In simple words: The planet that is farther from the Sun (planet Y) will take more time to go around the Sun because its path is longer and it moves slower.

🎯 Exam Tip: Remember Kepler's Third Law, which states that the square of the orbital period is proportional to the cube of the semi-major axis (average distance from the Sun).

Celestial Bodies and Indian Calendar Short Answer Type Questions

 

Question 19. Name the planets in series according to their distance from Earth?
Answer: The planets in series according to their distance from Earth are Venus, Mars, Mercury, Jupiter, Saturn, Uranus, Neptune. Venus and Mars are our closest neighbors, with Mercury being the third closest. The other planets are further away. This order can change slightly depending on the exact position of planets in their orbits. For example, Mercury is sometimes closer to Earth than Venus.
In simple words: The planets ordered by distance from Earth are Venus, Mars, Mercury, Jupiter, Saturn, Uranus, and Neptune.

🎯 Exam Tip: Be careful with questions asking for distance from Earth, as it differs from distance from the Sun. Venus and Mars are typically the closest to Earth at different points in their orbits.

 

Question 20. Name the main five and of Indian Panchang?
Answer: The Indian Panchang (calendar) is based on five main elements, also known as 'Panchangam'. These are vara (weekday), tithi (lunar day), nakshatra (Moon's asterism), yoga (angular relationship between Sun and Moon), and karana (half of a tithi). These five components together provide detailed astrological and astronomical information for each day. Understanding these helps in determining auspicious times and dates.
In simple words: The main five parts of the Indian Panchang are the weekday, lunar day, star sign (nakshatra), yoga, and karana.

🎯 Exam Tip: List all five components of the Panchang accurately and briefly explain each one if asked for a detailed answer.

 

Question 21. What do you mean by nakshatra? It is divided in how many parts? Name any five nakshatras?
Answer: Nakshatras are considered lunar mansions, which are specific divisions of the sky used in Vedic astrology. They are believed to influence people's lives and behavior. Vedic astrology divides the total 360-degree zodiac into 27 parts, each part being a Nakshatra and having its unique name. Each Nakshatra spans 13 degrees and 20 minutes.
They are:

In simple words: Nakshatras are sections of the sky used in Indian astrology, like lunar houses. The whole sky is divided into 27 Nakshatras. Ashvini is one such Nakshatra.

🎯 Exam Tip: Explain that Nakshatras are lunar mansions and state the total number of divisions. Providing examples like Ashvini strengthens your answer.

 

Question 22. Explain in brief how do you specify tithi on the basis of Indian Panchang?
Answer: In Vedic timekeeping, a tithi (also spelled thithi) is a lunar day, which is the time it takes for the longitudinal angle between the Moon and the Sun to increase by 12 degrees. Tithis start at different times of the day and can last between 19 and 26 hours. They are important in Hindu daily and special activities for choosing auspicious times (muhurta). There are both good and bad tithis. The bright fortnight (Shukla Paksha) has good tithis, while the dark fortnight (Krishna Paksha) has bad tithis. When the fast-moving moon's angle from the Sun changes by 12 degrees, that time interval is called Pratipada Tithi. This system helps mark specific lunar phases and their significance.
In simple words: A tithi is a lunar day, defined by the 12-degree angle between the Moon and the Sun. Tithis can be good or bad and are important for setting dates in the Indian calendar.

🎯 Exam Tip: Clearly define tithi as a lunar day based on the angle between the Sun and Moon, and mention its varying duration and importance in muhurta selection.

 

Question 23. Write the name of planets according to their size?
Answer: The names of planets according to their size, from smallest to largest, are: Mercury, Mars, Venus, Earth, Neptune, Uranus, Saturn, Jupiter. This order helps us understand the vast differences in physical dimensions across our solar system. Jupiter is the largest, while Mercury is the smallest. Knowing the relative sizes provides insight into their formation and characteristics.
In simple words: From smallest to largest, the planets are Mercury, Mars, Venus, Earth, Neptune, Uranus, Saturn, and Jupiter.

🎯 Exam Tip: Practice listing planets by size and by distance from the Sun separately, as the order is different for each.

 

Question 24. Explain the Uttarayan and Dakshinayan.
Answer: Uttarayan and Dakshinayan describe the Sun's apparent movement in the sky, marking different periods in the Indian calendar.

• Uttarayan: After December 22, the sunrise gradually shifts towards the east, continuing until June 21. This period, known as Uttarayan, is between Makar Sankranti and Karka Sankranti. It means the Sun is moving northward on the celestial hemisphere. During Uttarayan, the days are longer than the nights, bringing warmer weather to the northern hemisphere.
• Dakshinayan: The summer solstice occurs around June 21. From this date until December 22, the sunrise gradually shifts towards the south. This period is called Dakshinayan in Indian Astronomy, meaning the Sun is moving southward. It occurs between Karka Sankranti and Makar Sankranti. During Dakshinayan, the days are shorter than the nights. This leads to cooler weather in the northern hemisphere.

These movements are important for understanding seasonal changes and traditional festivals.
In simple words: Uttarayan is when the Sun appears to move north, making days longer. Dakshinayan is when the Sun appears to move south, making days shorter.

🎯 Exam Tip: Clearly define Uttarayan as the Sun's northward movement (longer days) and Dakshinayan as its southward movement (shorter days), mentioning their respective start and end dates.

 

Sun. Earth spins about its own imaginary axis like a top, from west to east. This motion of the Earth about its own axis, is called rotation. Earth completes one rotation about its own axis in 24 hours. Days and nights are formed due to the rotation of Earth about its own axis, in 24 hours. Seasons are caused due to the revolution of Earth around the Sun and the tilting of its axis of rotation.

 

Question 26. According to Indian Panchang, what type of motion is related to Rashi? How Rashis are specified?
Answer: In Indian Panchang, Rashi (zodiac sign) is related to the Moon's position at the time of birth. The Moon sign, or Rashi, is the zodiac sign where the Moon was located when a person was born. Rashis are specified by observing the Moon's revolution around the Earth, which influences its position in different zodiac signs. The Sun also moves along an elliptical path, passing through 12 Rashis and 27 Nakshatras (constellations) in the celestial sphere. This movement helps determine the specific Rashi for a given time, influencing astrological predictions.
In simple words: Rashis are connected to the Moon's position when someone is born. They are determined by tracking the Moon's path through the zodiac signs.

🎯 Exam Tip: Explain that Rashi refers to the Moon's zodiac sign at birth and is determined by celestial movements, especially the Moon's path through constellations.

 

Question 27. What do you mean by Makar Sankranti?
Answer: Makar Sankranti is a significant Hindu festival that marks the transition of the Sun into the zodiacal sign of Makara (Capricorn) on its celestial path. It is observed when the Earth moves from one Rashi (zodiac sign) to another. This festival is usually celebrated on January 14th each year and signifies the end of winter and the beginning of longer days. It also represents the beginning of Uttarayan, the Sun's northward journey.
In simple words: Makar Sankranti is a festival when the Sun moves into the Capricorn zodiac sign, marking the end of winter and the start of longer days.

🎯 Exam Tip: Define Makar Sankranti as the Sun's entry into Capricorn, its date, and its significance as marking the end of winter and the start of Uttarayan.

 

Question 28. What do you understand by Adhika Mass?
Answer: Adhika Mass, also known as Mai Mass, Londa Mass, or Purushottam Mass, is an extra month added to the Hindu calendar. This extra month is inserted to synchronize the lunar calendar with the solar year. The Hindu calendar is lunisolar, meaning it relies on both lunar months and the solar year. Since the lunar year is about 11 days shorter than the solar year, an Adhika Mass is added approximately every three years to compensate for these extra days. This ensures that festivals and seasons align correctly, preventing them from drifting over time. The position of this month in the Hindu calendar is not fixed and can occur between any two months.
In simple words: Adhika Mass is an extra month added to the Hindu calendar about every three years. It helps keep the lunar and solar calendars in sync.

🎯 Exam Tip: Explain Adhika Mass as an intercalary (extra) month in the lunisolar Hindu calendar, clarifying its purpose of realigning lunar and solar cycles.

 

Question 29. Explain the Transit of Mercury and compare it with Transit of Venus?
Answer: A transit of Mercury happens when the planet Mercury passes directly between the Sun and a superior planet (like Earth), making Mercury visible as a small dot moving across the Sun's disk. Mercury transits are more frequent than Venus transits, occurring about 13 or 14 times per century, mainly in May or November. This is because Mercury is closer to the Sun and orbits faster. The last transits were on November 15, 1999; May 7, 2003; November 8, 2006; and May 9, 2016.
In comparison, a transit of Venus happens when Venus passes directly between the Sun and a superior planet (like Earth). Transits of Venus are much rarer. The last one occurred on June 8, 2004. The next ones are predicted for December 10-11, 2117 and December 9, 2125. The infrequency of Venus transits makes them highly anticipated astronomical events. Both transits are rare and offer unique opportunities for scientific observation, helping astronomers measure the size of the solar system.
In simple words: A Transit of Mercury is when Mercury passes in front of the Sun, seen from Earth, which happens often. A Transit of Venus is when Venus passes in front of the Sun, which is much rarer.

🎯 Exam Tip: Clearly define what a planetary transit is and highlight the difference in frequency between Mercury and Venus transits, explaining why one is more common.

 

Question 30. Write the Solar months name according to Indian Panchang?
Answer: According to the Indian Panchang, the solar months are: Vaisakha, Jyaistha, Aashaadha, Sraavana, Bhaadrapada, Asvayuja (Aasvina), Kaarthika, Maarghasira, Pausa (Pushyam), Maagha, Phalguna, and Chaitra. These months are linked to the Sun's position in different zodiac signs and are used to mark seasons and festivals. Each month typically lasts about 30 days. This system helps keep track of the solar year.
In simple words: The Indian solar months are Vaisakha, Jyaistha, Aashaadha, Sraavana, Bhaadrapada, Asvayuja, Kaarthika, Maarghasira, Pausa, Maagha, Phalguna, and Chaitra.

🎯 Exam Tip: Memorize the names of the Indian solar months, as they are fundamental to understanding the Indian calendar system.

Celestial Bodies and Indian Calendar Long Answer Type Questions

 

Question 31. Write the biography of Aryabhatta and describe their main scientific works in detail?
Answer:
Aryabhatta: Aryabhatta was a celebrated mathematician and astronomer, born in Kusumapura (Patna) in Bihar, India, around 476 AD. His contributions to mathematics, science, and astronomy were immense, though not always fully recognized globally. At the age of 24, he authored his famous work "Aryabhatiya," a text comprising 108 verses and 13 introductory verses, divided into four chapters. He understood the concept of zero and could use very large numbers up to \(10^{18}\). Aryabhatta was aware that planets shine due to reflected sunlight and explained eclipses as shadows cast by the Moon and Earth. His observations laid the groundwork for the belief that Earth and other planets orbit the Sun. He also accurately calculated the value of \( \pi \) (pi) to four decimal places. This calculation showed his advanced understanding of geometry and numerical precision.
Scientific works and achievements:
Direct details of his work come from "Aryabhatiya," which his student Bhaskara I referred to as "Ashmakatantra."

• The first chapter, Gitikapada, discusses large units of time like Kalpa, Manvantra, and Yuga, introducing a new cosmology where planetary revolutions during a Mahayuga span 4.32 million years.
• Ganitapada, the second chapter, has 33 verses covering mensuration, arithmetic, geometric progressions, gnomon (shadows), simple, quadratic, simultaneous, and indeterminate equations. He provided a method for finding the area of a triangle, which stated: "for a triangle, the result of a perpendicular with the half-side is the area."
• Kalakriyapada, the third chapter, explains different units of time, a method for determining planet positions for a given day, and the seven-day week with names for each day.
• Golapada, the last chapter, describes geometric and trigonometric aspects of the celestial sphere, features of the ecliptic, celestial equator, Earth's shape, the cause of day and night, and zodiacal signs on the horizon.
• It is thought that Aryabhata used the term (approaching) for \( \pi \), suggesting it was not just an approximation but an incommensurable or irrational value.
• He studied sine functions, calling it "ardha-jya" or half-chord, showing early trigonometry.
• Like other ancient Indian mathematicians, he solved Diophantine equations (linear indeterminate equations), calling his method the "Kuttaka" (meaning 'breaking into pieces') method. This was an advanced technique for its time.
• His contributions to algebra were significant; he offered elegant formulas for sums of squares and cubes.
• He correctly concluded that planetary orbits are elliptical, a pioneering thought.

Other Achievements:
Aryabhatta provided knowledge of algebra, intermediate equations, trigonometry, the place value system, and zero. He also described the motions of the Solar system. His work was pivotal for later astronomical and mathematical developments.
In simple words: Aryabhatta was a famous Indian scientist who lived long ago. He wrote a book called "Aryabhatiya" where he talked about the concept of zero, numbers, how planets move, and how eclipses happen. He also figured out the value of \( \pi \) and explained why days and nights occur.

🎯 Exam Tip: When discussing Aryabhatta, highlight his birthplace, his primary work ("Aryabhatiya"), and his key contributions in mathematics (zero, \( \pi \), algebra) and astronomy (planetary motion, eclipses, elliptical orbits).

 

Question 32. Write the biography of Bhaskaracharya? and describe their main scientific works in detail?
Answer:
Bhaskara II, also known as Bhaskaracharya, was a renowned 12th-century Indian mathematician and astronomer, born in 1114 near Vijjadavida (modern Bijjaragi in Karnataka). He accurately defined many astronomical quantities, including the precise length of the sidereal year. Bhaskaracharya made significant discoveries in differential calculus and applied them to astronomical problems and computations centuries before European mathematicians like Newton and Leibniz. He is regarded as the greatest mathematician of medieval India for his invaluable contributions. His work demonstrated an advanced understanding of mathematical principles far ahead of his time.
Scientific work and achievements:
1. Bhaskaracharya made many important contributions to mathematics. He provided a proof of the Pythagorean theorem by calculating the same area in two different ways and then canceling out terms to derive \( a^2 + b^2 = c^2 \). This showed a deep understanding of geometric proofs.
2. His work on calculus was groundbreaking. He not only discovered the principles of differential calculus and its use in astronomical problems but also found solutions for linear and quadratic indeterminate equations (Kuttaka). His calculus methods were comparable to those developed by European mathematicians in the 17th century, showing how advanced Indian mathematics was. He did this centuries before.
3. His first work, "Lilavati," has 13 chapters covering definitions, arithmetic, interest calculations, progressions, plane and solid geometry, and methods for computing numbers like multiplication and squares. This book made complex math accessible.
4. His work "Bijaganita" ("Algebra") has 12 chapters, discussing positive and negative numbers, zero, surds, unknown quantities, and the 'Kuttaka' method for solving indeterminate equations. He improved upon Brahmagupta's earlier work.
5. The sections 'Ganitadhyaya' and 'Goladhyaya' of his "Siddhanta Shiromani" are about astronomy. He used an astronomical model by Brahmagupta to precisely define various astronomical quantities, including the length of the sidereal year. These sections cover planetary longitudes, eclipses, cosmography, and geography. His observations were very detailed and accurate.
6. Bhaskara II was known for his in-depth knowledge of trigonometry. His works include computations of sine of angles like 18 and 36 degrees. He is credited with discovering spherical trigonometry, a branch of spherical geometry crucial for astronomical and geodetic calculations. This advanced understanding was vital for accurate celestial observations.
7. His major work, "Siddhanta Siromani," is divided into four parts, each dealing with various topics in arithmetic, algebra, calculus, trigonometry, and astronomy. He is considered a pioneer in calculus and likely the first to develop the differential coefficient and differential calculus. His insights provided a foundation for future mathematical advancements. He was truly a visionary in both mathematics and astronomy.
In simple words: Bhaskaracharya was an Indian scientist who lived a long time ago. He invented ideas like differential calculus for math and found solutions to many complex math problems. His books also explained how planets move and how big the sidereal year is.

🎯 Exam Tip: Focus on Bhaskara II's birth period, his pioneering work in calculus and indeterminate equations, and his major texts like "Lilavati," "Bijaganita," and "Siddhanta Shiromani."

 

Question 33. What is the base of naming the Indian months? Write the name of the Indian months and describe their position in the sky at that time.
Answer: The Indian calendar system is intricate, with many calendars linked by their month names. The naming of Indian months is primarily based on the Nakshatra (lunar asterism) where the full moon occurs. If a full moon happens near a specific Nakshatra, the month is named after that Nakshatra. For example, if a full moon occurs near the Visakha Nakshatra, the month is called Vaisakha Purnimasi, and the month becomes Vaisakha. This ancient rule ensures that the full moon's position corresponds to the month's name. Fifteen Nakshatras were historically used for naming, spaced relatively equally.
Here is a list of Rashis with their approximate Nakshatras and corresponding lunar and solar month names:

In simple words: Indian months are named after the star group (Nakshatra) where the full moon appears. For example, if the full moon is near the Chitra star group, the month is called Chaitra. This helps link the lunar calendar with what we see in the sky.

🎯 Exam Tip: Explain the Purnimanta system (naming month after Nakshatra during full moon) and provide examples from the table to illustrate the concept clearly.

 

Question 34. Explain our Solar System in detail?
Answer: Our Solar System consists of the Sun, eight planets, their moons, asteroids, comets, and meteors, all held together by gravity. It's a vast and dynamic system with many components orbiting our central star.
The Sun: It is the largest star in our solar system and its diameter is 109 times that of Earth. The Sun is about 300,000 times heavier than Earth and is a massive, bright ball made of hydrogen and helium gases. It is the main source of energy for the entire solar system. Day and night cycles, changes in seasons, and rain formation all happen because of the Sun's energy. Life on Earth completely depends on solar energy. The Sun's powerful gravitational pull keeps all the planets in orbit.
Planets: A planet is a solid, heavenly body that revolves around the Sun in a closed elliptical orbit. There are eight planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. All planets rotate from west to east, except Venus, which rotates from east to west. Their differing speeds cause their positions relative to Earth to change daily. In Indian astronomy, planets are called Graha. The unique characteristics of each planet contribute to the diversity of our solar system.
Here are details about some planets:
1. Mercury [Budha]: This is the first planet from the Sun and the closest. It is one of the hottest planets due to its proximity to the Sun. Its surface looks like the Moon, with many craters. Mercury has no water or atmosphere, making life impossible because of its extremely high temperature and harsh conditions.
2. Venus [Shukraj]: This is the second planet from the Sun. It outshines all other heavenly bodies except the Sun and Moon, making it the brightest and hottest planet. It appears as an evening star for 292 days in the western sky and then as a morning star for another 292 days in the eastern sky. Despite being second from the Sun, it is brighter than Mercury due to its thick, cloudy carbon dioxide atmosphere, which reflects a lot of sunlight. Its mass is 0.8 times Earth's mass, and its size is similar to Earth's.
3. Earth [Prithvi]: This is the third planet from the Sun. Earth's axis of rotation is tilted and always points in the same direction. This tilt causes the Northern and Southern Hemispheres to change their orientation towards the Sun throughout the year, leading to seasons. Earth completes one rotation on its axis in 24 hours, causing days and nights. Life thrives here due to the presence of water and a suitable atmosphere.
4. Mars [Mangal]: It appears as a red star and is often called the Red Planet. Mars has two small moons, Phobos and Deimos, which are very close to its surface and less than 20 km in diameter. The reddish color is due to iron oxides on its surface.
5. Jupiter [Guru or Brihaspati]: This is the largest planet in our solar system. A notable feature is its Great Red Spot, a storm larger than Earth. Jupiter has 61 known moons and a faint ring around its equator. Its immense size influences the orbits of other celestial bodies.
6. Saturn [Shani]: Saturn is famous for its three flat rings, made of rocks ranging from tiny specks to kilometers in diameter. The second ring, B, is the brightest. Saturn has 31 known moons. The beautiful ring system makes Saturn one of the most recognizable planets.
Asteroids: These are small pieces of rocks or metals that orbit the Sun, mostly found in the asteroid belt between Mars and Jupiter. They are remnants from the early formation of the solar system.
Comets: These are bright, star-like objects with long tails that approach the Sun in highly elliptical orbits. They are made of ice, dust, and rock, and their tails form as they get closer to the Sun and the ice vaporizes.
Meteors: These are bright, star-like objects that appear suddenly in the sky as brilliant flashes of light and then disappear. They are believed to be debris from comets. When a meteor enters Earth's atmosphere, it heats up due to friction, burns up, and creates a "shooting star" effect, though they are not actual stars.
Our solar system is a complex and beautiful collection of celestial objects, each playing a unique role.
In simple words: Our Solar System has the Sun, eight planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune), moons, asteroids, comets, and meteors. The Sun gives us light and heat. Planets go around the Sun, and some have moons. Asteroids are small rocks, comets have tails, and meteors are "shooting stars" that burn up in the sky.

🎯 Exam Tip: For explaining the solar system, start with the Sun's role, then list and briefly describe each planet and other celestial bodies (asteroids, comets, meteors), noting their key characteristics and relative positions.

Multiple Choice Questions (MCQs)

 

Question 1. Celestial bodies which have their own light and heat are known as:
(a) Stars
(b) Planets
(c) Satellites
(d) Meteors
Answer: (a) Stars
In simple words: Objects in space that make their own light and heat are called stars. Our sun is an example of a star.

🎯 Exam Tip: Remember that planets reflect light from a star, they don't produce their own light.

 

Question 2. Moon is categorised in which series of solar system?
(a) Star
(b) Planet
(c) Satellite
(d) Asteroid
Answer: (c) Satellite
In simple words: The Moon goes around the Earth, so it is a natural satellite of Earth.

🎯 Exam Tip: Natural satellites orbit planets, while planets orbit stars.

 

Question 3. According to Indian Panchang, the number of Nakshatra are:
(a) 15
(b) 27
(c) 12
(d) 07
Answer: (b) 27
In simple words: The Indian calendar, called Panchang, divides the sky into 27 parts, each called a Nakshatra. These are like groups of stars.

🎯 Exam Tip: Nakshatras are used in traditional Indian astronomy and astrology to track the moon's position.

 

Question 4. According to Indian Panchang the number of Rashis are:
(a) 15
(b) 12
(c) 12
(d) 07
Answer: (b) 12
In simple words: In the Indian calendar system (Panchang), there are 12 Rashis, which are similar to zodiac signs.

🎯 Exam Tip: Rashis represent the zodiac divisions and are used to understand planetary positions and their effects.

 

Question 6. Which is the largest planet in our Solar System:
(a) Jupiter
(b) Saturn
(c) Uranus
(d) Neptune
Answer: (a) Jupiter
In simple words: Jupiter is the biggest planet in our solar system, much larger than all the other planets combined.

🎯 Exam Tip: Remembering the order and size of planets helps in understanding the solar system structure.

 

Question 7. After how many years did Adhik Mass occurs?
(a) After 1 year
(b) After 2 years
(c) After 3 years
(d) After 4 years
Answer: (c) After 3 years
In simple words: An extra month, called Adhik Maas, is added to the Hindu calendar usually every three years to keep the lunar and solar calendars aligned.

🎯 Exam Tip: Adhik Maas is important for balancing the Hindu lunisolar calendar, ensuring festivals fall in the correct seasons.

 

Question 8. In which Rashi, Sun is located after starting of Dakshinayan?
(a) Cancer
(b) Leo
(c) Capricorn
(d) Aquarius
Answer: (a) Cancer
In simple words: When the Sun begins its southward journey, known as Dakshinayan, it enters the Cancer Rashi. This marks a change in the season.

🎯 Exam Tip: Dakshinayan marks the period when the sun moves south of the celestial equator, leading to shorter days in the northern hemisphere.

 

Question 9. Planets are heavenly bodies which:
(a) Revolve round the sun in the same way as our earth
(b) are eight in numbers
(c) do not twinkle
Answer: Not available in source.
In simple words: Planets are large objects in space that orbit a star. They differ from stars because they don't produce their own light and usually don't twinkle when viewed from Earth.

🎯 Exam Tip: Understand the key differences between planets and stars, such as light production, twinkling, and orbital paths.

 

Question 11. Nakshatra is divided into how many parts?
(a) 2
(b) 4
(c) 6
(d) 9
Answer: (b) 4
In simple words: Each Nakshatra, which is a segment of the zodiac in Indian astronomy, is further divided into 4 smaller parts.

🎯 Exam Tip: Each of these smaller parts, or 'padas', is used in detailed astrological calculations.

 

Question 12. A planet which is commonly called Evening Star:
(a) Mercury
(b) Venus
(c) Pluto
(d) Mars
Answer: (b) Venus
In simple words: Venus is often called the Evening Star because it is very bright and can be seen in the sky around sunset. It is actually a planet, not a star.

🎯 Exam Tip: Venus is visible either in the evening shortly after sunset or in the morning shortly before sunrise, making it distinct.

 

Question 13. The number of planets according to Indian Panchang are:
(a) 7
(b) 10
(c) 8
(d) 9
Answer: (d) 9
In simple words: In Indian Panchang and traditional astrology, nine planets are considered important, including the Sun and Moon, along with the actual planets.

🎯 Exam Tip: Note that the Indian Panchang includes luminaries and shadow planets (Rahu and Ketu) in its count of 'planets' for astrological purposes, unlike modern astronomy.

 

Question 14. Pratipada tithi will be the interval of:
(a) 12-24
Answer: Not available in source.
In simple words: Pratipada Tithi is the first lunar day of each fortnight in the Hindu calendar. It signifies the start of a new lunar phase.

🎯 Exam Tip: Understanding Tithis helps in following the traditional Hindu calendar and identifying auspicious days.

 

Question. Siddhanta Siromani is written by:
(a) Aryabhatta
(b) Bhaskara
(c) Bhaskara II
(d) Varamihira
Answer: (c) Bhaskara II
In simple words: The famous book "Siddhanta Siromani" was written by the ancient Indian mathematician and astronomer Bhaskara II.

🎯 Exam Tip: Knowing key authors and their works in ancient Indian science is important for historical context.

Celestial Bodies and Indian Calendar Very Short Answer Type Questions

 

Question 1. Name the bodies of the solar system that have failed to assemble into a planet?
Answer: Asteroids.
In simple words: Asteroids are small rocky objects that orbit the Sun but did not come together to form a planet.

🎯 Exam Tip: Asteroids are often found in the asteroid belt between Mars and Jupiter.

 

Question 2. Name the planet that is known to have the largest number of natural satellites.
Answer: Saturn, having 30 satellites.
In simple words: Saturn has the most natural moons among all the planets, with 30 known ones orbiting it.

🎯 Exam Tip: The number of known moons for giant planets can change as new discoveries are made with advanced telescopes.

 

Question 3. Which planet of the solar system is largest and smallest in size?
Answer:
(a) Largest planet- Jupiter
(b) Smallest planet- Mercury.
In simple words: Jupiter is the largest planet in our solar system, while Mercury is the smallest one.

🎯 Exam Tip: Visualizing the planets in order of size helps in remembering their relative dimensions.

 

Question 4. Who gave the relation between circumference and diameter of circle?
Answer: Aryabhatta.
In simple words: Aryabhatta, an ancient Indian mathematician, was the first to explain how the distance around a circle (circumference) relates to its width through the center (diameter).

🎯 Exam Tip: Aryabhatta's contributions were fundamental to both mathematics and astronomy in ancient India.

 

Question 5. Rashi contains how many charans?
Answer: Not available in source.
In simple words: In Vedic astrology, each Rashi (zodiac sign) is divided into a certain number of smaller parts called charans, which help in precise calculations.

🎯 Exam Tip: Charans are used for more detailed astrological interpretations within each Rashi.

 

Question 7. Name the two satellites of Mars?
Answer: Phobos and Deimos.
In simple words: Mars has two small moons, which are named Phobos and Deimos.

🎯 Exam Tip: Phobos and Deimos are believed to be captured asteroids rather than formed alongside Mars.

 

Question 8. How does the phases of moon occurs?
Answer: The phases of moon occur due to the changing positions of the Earth and Moon as the Moon revolves around the Sun. The amount of sunlight we see reflected from the Moon changes, causing its phases.
In simple words: The Moon's appearance changes because we see different amounts of its sunlit side as it moves around Earth.

🎯 Exam Tip: The phases of the Moon are determined by the Sun-Earth-Moon alignment.

 

Question 9. What are Asteroids?
Answer: Asteroids are small pieces of rocks or metals that orbit the Sun. They are mostly found between the orbits of Mars and Jupiter in the asteroid belt.
In simple words: Asteroids are like small, rocky leftovers from when our solar system was formed. They mostly live between Mars and Jupiter.

🎯 Exam Tip: Asteroids are too small to be called planets and too large to be called meteoroids.

 

Question 10. What are comets?
Answer: Comets are bright, shiny, star-like objects with a long tail that approach the Sun in a highly elliptical orbit. They are made of ice, dust, and rock.
In simple words: Comets are icy space rocks that grow a tail when they get close to the Sun, making them look like bright stars with a long streak.

🎯 Exam Tip: A comet's tail always points away from the Sun due to solar wind pressure.

Celestial Bodies and Indian Calendar Short Answer Type Questions

 

Question 1. What are celestial bodies? Name some of these?
Answer: Celestial bodies are natural objects found outside Earth's atmosphere, which can be small or massive. They include everything in space like stars, the Sun, the Moon, and planets. These bodies follow specific paths and are governed by natural laws.
In simple words: Celestial bodies are all the natural things we see in space, like stars, our Sun, the Moon, and other planets.

🎯 Exam Tip: Celestial bodies encompass all natural objects in the universe, from dust particles to galaxies.

 

Question 3. What are the Planets? How are they different from a Star?
Answer: A planet is a large, solid heavenly body that revolves around a star in a closed, circular (or elliptical) orbit. They do not produce their own light but reflect light from the stars they orbit.
Star:
1. Stars have their own light.
2. Stars produce their own energy through nuclear fusion.
3. Stars appear to twinkle at night due to Earth's atmosphere.
4. Stars have enormous mass.
5. Stars do not change their relative position in the sky noticeably from Earth, though they do move over very long periods.
6. Stars appear to move from east to west in the sky due to Earth's rotation.
Planet:
1. Planets do not have their own light; they reflect light from a star.
2. Planets do not produce their own energy; they depend on the Sun for energy.
3. Planets typically do not twinkle at night because they are closer and appear as discs.
4. Planets have insignificant mass compared to stars.
5. Planets change their position in the sky daily as they orbit the Sun.
6. Planets appear to rotate from west to east in the sky for most (except Venus) as viewed from Earth.
In simple words: Planets are big space rocks that go around a star and only shine because they reflect the star's light. Stars are huge balls of gas that make their own light and heat. Stars twinkle, but planets usually don't.

🎯 Exam Tip: Focus on the two main differences: light source (own vs. reflected) and twinkling (yes vs. no), as these are easy to remember distinctions.

 

Question 4. Classify the following into planets, satellites, stars and constellation. Moon, Alpha centuri, Neptune, Orion, Mercury, Ursa major, Sun, Phobos.
Answer:
Planets: Neptune, Mercury.
Stars: Alpha Centuri, Sun.
Constellations: Orion, Ursa Major.
Satellite: Moon, Phobos.
In simple words: We can put space objects into groups: Neptune and Mercury are planets. Alpha Centuri and the Sun are stars. Orion and Ursa Major are star patterns (constellations). The Moon and Phobos are satellites because they orbit planets.

🎯 Exam Tip: Remember that satellites orbit planets, planets orbit stars, and constellations are patterns of stars.

 

Question 6. Why Uttarayan is considered as an auspicious period?
Answer: In Hindu religion, people believe that if a person passes away during Uttarayan, their soul is thought to go to heaven. This belief makes Uttarayan a very sacred and lucky time.
In simple words: Many Hindus believe that dying during Uttarayan helps a soul go to heaven, so it is seen as a very good time.

🎯 Exam Tip: Mentioning the religious belief about attaining heaven is key to answering this question fully.

 

Question 7. What are Basant and Sharad equinox?
Answer: An equinox is an astronomical event where the plane of Earth's equator passes directly through the center of the Sun. This happens twice a year, around March 20 (Basant Equinox) and September 23 (Sharad Equinox). During an equinox, days and nights are almost exactly equal in length all over the planet due to the Sun's position and how light bends in the atmosphere.
In simple words: Basant (spring) and Sharad (autumn) equinoxes are times of the year when day and night are almost the same length. This happens when the Earth's middle line (equator) points directly at the Sun.

🎯 Exam Tip: The key characteristic of an equinox is the near-equal duration of day and night globally.

Celestial Bodies and Indian Calendar Long Answer Type Questions

 

Question 1. Write the biography of Varamihira and explain the scientific works of Varamihira in detail?
Answer: Varahamihira was born in 499 A.D. into a Brahmin family living in Kapittha, a village near Ujjain. His father, Adityadasa, who worshipped the Sun god, taught him astrology. During a visit to Kusumapura (Patna), young Varahamihira met the great astronomer Aryabhatta, which greatly inspired him to dedicate his life to astrology and astronomy. Ujjain was a vibrant learning center during the Gupta reign, attracting scholars from many places, so Varahamihira moved there.

Eventually, his astrological skills were recognized by Vikramaditya Chandragupta II, who made him one of his court's Nine Gems. Varahamihira made significant mathematical contributions, including the discovery of trigonometric formulas. He improved the accuracy of Aryabhata-I's sine tables and defined algebraic properties for zero and negative numbers. He was also among the first mathematicians to discover a version of Pascal's triangle, using it to calculate binomial coefficients. He believed that planets shine due to reflected sunlight and that eclipses are caused by the shadows of the Moon and Earth. His observations supported the idea of a spherical Earth and other planets orbiting the Sun. He even suggested a "Force" might be keeping bodies stuck to the round Earth, which is now understood as gravity. Varahamihira's work "Panch Siddhanta" summarizes five older astronomical texts and is a significant treatise on mathematical astronomy.
In simple words: Varahamihira was a wise Indian scholar born around 499 A.D. He learned astrology from his father and was inspired by Aryabhatta. He made important discoveries in math, like formulas for circles and rules for zero. He also helped explain why planets shine and how eclipses happen, and thought Earth was round. He was a key figure in ancient Indian science.

🎯 Exam Tip: When describing a biography, include birth details, key influences, major works, and significant scientific contributions in chronological order.

 

Question 2. Explain the phases of the Moon.
Answer: The Moon is not luminous; it does not produce its own light. Instead, it reflects light from the Sun. We see the Moon because this reflected sunlight reaches Earth. The visible part of the Moon depends on how much of its sunlit surface faces Earth. On New Moon Day, the Moon is between the Sun and Earth, so the sunlit side faces away from us, making it invisible.

After the New Moon, we begin to see a crescent moon. This happens because a small part of the sunlit side becomes visible. The crescent grows larger each day, until, on the fifteenth day (Full Moon Day), the entire sunlit face of the Moon is visible. This occurs when Earth is between the Sun and Moon. This increasing brightness is called waxing of the moon.

After the Full Moon, the bright face of the Moon starts to get smaller each night. This decrease in visible light is called waning of the moon. After another fifteen days, the New Moon returns, completing the cycle. These changes in the Moon's appearance, caused by its revolution around Earth, are known as the phases of the Moon.
In simple words: The Moon's phases happen because we see different amounts of its lit-up side as it orbits Earth. It doesn't make its own light, it just reflects the Sun's light. So, sometimes we see a thin crescent, sometimes a full circle, and sometimes no Moon at all.

🎯 Exam Tip: Use simple terms like 'waxing' for growing and 'waning' for shrinking to describe the moon's illuminated phase change.