All questions of Introduction to Earth & Universe for BPSC (Bihar) Exam

Before and after the quarter-moon phases are the gibbous and crescent phases. During the gibbous moon phase, the moon is more than half lit but not full.  During the crescent moon phase, the moon is less than half lit and is seen as only a sliver or crescent shape. 

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The Goldilocks Zone refers to the habitable zone. The habitable zone is the area around a star where it is not too hot nor too cold for liquid water to exist on the surface of surrounding planets.

Statement Analysis:

Statement-I:
- Summer: Sun is overhead, sunrays fall almost vertically, heat concentrated on a small area, temperatures rise.
- Conclusion: Summers are warm.

Statement-II:
- Winter: Oblique sun rays, less direct, heat absorbed by atmosphere and water vapor, sun rays spread over a greater area, temperatures remain low.

Correct Interpretation:
- Both statements are correct, but they present different scenarios for why temperatures vary between summer and winter.
- In summer, the direct and concentrated heat from the overhead sun leads to high temperatures.
- In winter, the indirect and dispersed heat from oblique sun rays results in lower temperatures.
- Therefore, Statement-I is correct in explaining the warmth of summers, while Statement-II correctly describes the cool temperatures of winters.

Understanding the Statements
The two statements provided relate to the Earth's rotation and its effects on velocity.
Statement-I: Earth's Rotation Direction
- The Earth indeed rotates on its axis from west to east.
- This rotation is in an anticlockwise direction when viewed from above the North Pole.
- This movement is responsible for the daily cycle of day and night.
Statement-II: Variation of Velocity
- The velocity of the Earth's rotation is highest at the equator and decreases as one moves toward the poles.
- At the equator, the linear velocity is approximately 1,670 kilometers per hour due to the larger circumference.
- As you move toward the poles, the circumference decreases, resulting in lower linear velocities.
Correctness of the Statements
- Both statements are accurate:
- Statement-I correctly describes the direction of Earth's rotation.
- Statement-II accurately explains the change in rotational velocity from the equator to the poles.
Relationship Between Statements
- While both statements are correct, Statement-II does not explain Statement-I.
- Statement-I describes the direction of rotation, while Statement-II discusses the variation in rotational speed, which is a separate concept.
Conclusion
- Therefore, the correct answer is option 'B': Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I.
This explanation provides clarity on the nature of the Earth's rotation and the implications of its velocity at different latitudes.

Understanding Earth's Features
To evaluate the correctness of the statements regarding Earth's features, let's analyze each one.
1. Earth's Axis Inclination
- The Earth's axis is indeed inclined at an angle of approximately 23.5° to the perpendicular of the ecliptic plane.
- This tilt is responsible for the seasonal variations we experience as the Earth orbits the Sun.
2. Tropic of Cancer and Winter Solstice
- The statement that the Tropic of Cancer receives vertical sunrays at the winter solstice is incorrect.
- During the winter solstice (around December 21), the Sun is directly overhead at the Tropic of Capricorn (23.5°S), not the Tropic of Cancer (23.5°N). The Tropic of Cancer receives vertical rays at the summer solstice (around June 21).
3. Length of Latitudes
- The statement about the length of latitudes decreasing from the equator to the poles is correct.
- This is because lines of latitude are circles, with the equator being the largest circle and the poles being points, resulting in a gradual decrease in circumference as one moves towards the poles.
Conclusion
- Thus, the correct statements are:
- Statement 1 is correct.
- Statement 2 is incorrect.
- Statement 3 is correct.
Accordingly, the correct answer is option 'C' (1 and 3 only).

A nebula is an interstellar cloud of dust, hydrogen, helium, and other gases. Nebulae are often star-forming regions, where gas, dust 'clump' together to form larger masses, which eventually become massive enough to form stars.

According to the Big Bang theory, everything in the universe developed from a point known as singularity, 15 billion years ago at an affixed moment in time. “As the universe expanded for 15 billion years, the hot radiation in the original fireball also expanded with it, and cooled as a result.”

Analysis of the given pairs:
Winter Solstice: Day lasts for 6 months at the South Pole
- This pair is correctly matched. During the Winter Solstice, the South Pole experiences 24 hours of daylight for about 6 months.
Equinoxes: Suns rays are vertical at the Tropic of Cancer on 21 March and 21 September
- This pair is incorrect. During the equinoxes, the Sun's rays are vertical at the Equator, not the Tropic of Cancer.
Summer Solstice: Suns rays fall vertically at the Tropic of Capricorn on 21 June
- This pair is correctly matched. During the Summer Solstice, the Sun's rays fall vertically at the Tropic of Capricorn.
Seasonal Changes: Longer days in summer lead to higher temperatures
- This pair is correctly matched. Longer days in summer result in more sunlight which leads to higher temperatures.
Therefore, out of the four pairs given, only two pairs are correctly matched. The correct answer is option 'A' - Only two pairs.

Collision Hypothesis by Harold Jeffreys

Introduction:
Harold Jeffreys was a British mathematician and geophysicist who proposed the Collision Hypothesis in the 1930s. This hypothesis explains the formation of celestial bodies, especially the formation of stars.

Theory:
The Collision Hypothesis suggests that three stars collided with each other and merged to form a single star. This single star then attracted more matter from the surrounding space and eventually became a full-fledged star.

Explanation:
According to the Collision Hypothesis, the three stars that collided were relatively small and had a low mass. These stars were moving in close proximity to each other and eventually collided due to the gravitational attraction between them.

The collision resulted in the formation of a single star that had a much larger mass than the individual stars that collided. This new star then started attracting more matter from its surroundings due to its increased gravitational force.

Over time, this process of accretion continued, and the star grew in size and mass. Eventually, it became a full-fledged star and started emitting light and heat.

Conclusion:
In conclusion, the Collision Hypothesis proposed by Harold Jeffreys suggests that the formation of stars can be attributed to the collision of three small stars that merge to form a larger star. This hypothesis helps in understanding the formation and evolution of stars and has been widely accepted by the scientific community.

Shape of the Earth: Oblate Spheroid
The Earth is not a perfect sphere; instead, it takes the shape of an oblate spheroid. This means that the planet is slightly flattened at the poles and bulging at the equator.
Reasons for the Oblate Shape:
- Rotation: The Earth's rotation causes the equatorial region to experience a centrifugal force, which leads to a bulging effect. This is due to the speed of rotation being greatest at the equator.
- Gravity: The force of gravity pulls everything toward the center of the Earth. However, because of the rotational force, the bulge at the equator counteracts some of this pull, resulting in a slight flattening at the poles.
- Measurements: Scientific measurements demonstrate that the equatorial diameter is about 43 kilometers larger than the polar diameter. This difference supports the classification of the Earth as an oblate spheroid.
Implications of the Oblate Shape:
- Geodesy: Understanding the Earth's shape is crucial for geodesy, which is the study of Earth’s geometric shape, orientation in space, and gravity field.
- Navigation and Mapping: The oblate spheroid shape has implications in global positioning systems (GPS) and mapping, affecting calculations regarding distances and areas.
- Climate and Weather Patterns: The Earth's shape influences weather patterns and ocean currents, which are vital for understanding climate systems.
In conclusion, the Earth's oblate spheroid shape is a result of its rotation and gravitational forces, affecting various scientific fields and practical applications.

  The rotatory motion of the planets (expect Venus and Uranus) is in the same direction as their revolution around the sun. 

1. Meteoroids: These are small rocky or metallic fragments that travel through space and enter the Earth's atmosphere. They are typically the size of a pebble or smaller.

2. Asteroids: These are larger rocky fragments that orbit the Sun and occasionally cross paths with Earth's orbit. When they enter the Earth's atmosphere, they are called meteors.

3. Cometary debris: Comets are made up of ice, dust, and rocky fragments. When a comet gets close to the Sun, the heat causes the ice to vaporize, releasing debris into space. Some of this debris can enter the Earth's atmosphere as meteors.

4. Space debris: This includes fragments of satellites, rockets, and other human-made objects that have been left in space. When these objects re-enter the Earth's atmosphere, they can burn up and become meteors.

5. Tektites: These are glassy fragments that are formed when a large meteorite impacts the Earth's surface. The intense heat and pressure from the impact melt the surrounding rocks, creating tektites that are ejected into the atmosphere.

6. Lunar meteorites: These are fragments of the Moon's surface that are ejected during meteorite impacts on the Moon. Some of these fragments can escape the Moon's gravity and enter the Earth's atmosphere as meteors.

7. Martian meteorites: Similar to lunar meteorites, these are fragments of Mars that are ejected during meteorite impacts on the Martian surface. Some of these fragments can make their way to Earth as meteors.

It's important to note that while these rocky fragments can endure passage through the Earth's atmosphere, most of them burn up due to the intense heat generated by friction with the air. Only a small fraction of the original fragments survive and reach the Earth's surface as meteorites.

  According to the Tidal Hypothesis, there was a great impact of the tidal force of the intruding star on the surface of the primitive sun. When the ‘intruding star’ came nearest to the ‘primitive sun’ its gravitational force became maximum, resulting in a giant cigar-shaped mass called a filament- thick in the centre and thin and sharp at the ends.

Spiral galaxy, milky way galaxy have four spirals, so the correct answer is option 'C'.

Laplace’s Hypothesis, also known as the Gaseous Hypothesis, was a modified version of the Nebular Hypothesis.

1. Nebular Hypothesis:
The Nebular Hypothesis, proposed by Immanuel Kant and further developed by Pierre-Simon Laplace in the late 18th century, suggests that the Solar System was formed from a large rotating cloud of gas and dust called the solar nebula. According to this hypothesis, the solar nebula began to contract and spin due to its own gravitational pull. As it contracted, it started to flatten into a spinning disk shape with a bulge at the center.

2. Laplace’s Modification:
Laplace modified the Nebular Hypothesis by proposing what is now known as Laplace’s Hypothesis or the Gaseous Hypothesis. He suggested that the Sun and the planets were formed from a single rotating mass of gas and dust, rather than a solar nebula. According to Laplace, this original mass was a hot, gaseous disk that extended beyond the orbit of the furthest planet.

3. Formation of the Solar System:
Laplace’s Hypothesis explains the formation of the Solar System in the following steps:

a) Formation of the Sun:
The initial rotating mass of gas and dust began to contract due to gravity. As it contracted, the central region became denser and hotter, eventually forming the Sun. The contraction also caused the rotation to accelerate, leading to the formation of a spinning disk around the Sun.

b) Formation of Planets:
Within the spinning disk, particles of gas and dust started to collide and stick together, forming larger bodies called planetesimals. Through further collisions and gravitational interactions, these planetesimals grew in size to become protoplanets. Eventually, these protoplanets accreted more material and formed the planets of the Solar System.

c) Conservation of Angular Momentum:
Laplace's Hypothesis also explains the conservation of angular momentum in the formation of the Solar System. As the initial rotating mass contracted, its rotation speed increased due to the conservation of angular momentum. This increased rotation speed caused the central region to flatten into a disk shape, which is observed in the current Solar System.

4. Importance and Legacy:
Laplace's Hypothesis provided a comprehensive explanation for the formation of the Solar System and became widely accepted in the scientific community. It laid the foundation for the modern understanding of planetary formation and influenced subsequent theories in astronomy and astrophysics. Although some aspects of Laplace's Hypothesis have been refined and modified over time, it remains a significant contribution in the field of planetary science.

It was suggested that the material forming the moon was separated from what we have at present the depression occupied by the Pacific Ocean.

In 1838, Sir George Darwin suggested that initially, the earth and the moon formed a single rapidly rotating body.

Out of the eight planets, Mercury, Venus, Earth and Mars are called “the inner planets” as they lie between the Sun and the belt of asteroids.

Understanding the Latitude Lines
The pairs presented include significant latitudinal lines that delineate different climatic zones and geographical features. Let's evaluate each pair for accuracy.
Correctly Matched Pairs
1. Tropic of Cancer
- Latitude: 23.5° North of Equator
- Status: Correctly matched
2. Tropic of Capricorn
- Latitude: 23.5° South of Equator
- Status: Correctly matched
Incorrectly Matched Pairs
3. Arctic Circle
- Latitude: 66.5° North of Equator (not South)
- Status: Incorrectly matched
4. Antarctic Circle
- Latitude: 66.5° South of Equator (not North)
- Status: Incorrectly matched
Conclusion
From the evaluation:
- Tropic of Cancer: Correct
- Tropic of Capricorn: Correct
- Arctic Circle: Incorrect
- Antarctic Circle: Incorrect
Thus, only the first two pairs are accurately matched, leading to the conclusion that the answer is "Only two pairs". The correct option is B.
Understanding these latitudinal markers is crucial for geographical studies, as they influence climate, biodiversity, and daylight patterns across the globe.

**The Gaseous Hypothesis - Proposed by Immanuel Kant**

**Introduction:**
The Gaseous Hypothesis, also known as the Kant-Laplace hypothesis, was proposed by the German philosopher Immanuel Kant in the 18th century. This hypothesis aimed to explain the origin and formation of the solar system, particularly focusing on the formation of the planets.

**Explanation:**

**1. The Nebular Hypothesis:**
The Gaseous Hypothesis is a part of the broader concept known as the nebular hypothesis. According to this hypothesis, the solar system formed from a huge rotating cloud of gas and dust called the solar nebula. As the nebula contracted under its own gravity, it began to spin faster and flatten into a spinning disk.

**2. The Role of Kant:**
Immanuel Kant, a renowned philosopher, proposed the Gaseous Hypothesis as a possible explanation for the formation of the solar system. He suggested that the solar nebula, composed of primordial gas and dust, began to collapse under its own gravity. As it collapsed, it started to spin and flatten into a disk shape due to conservation of angular momentum.

**3. The Role of Laplace:**
Although the Gaseous Hypothesis is often attributed to Kant, it was further developed and popularized by the French mathematician Pierre-Simon Laplace in the late 18th century. Laplace expanded on Kant's ideas and provided mathematical explanations for the formation of the solar system.

**4. Formation of Planets:**
According to the Gaseous Hypothesis, the flattened disk of the solar nebula eventually formed a central mass, which became the sun. The remaining material in the disk began to aggregate and form smaller clumps called planetesimals. These planetesimals collided and merged over time to form protoplanets, which later became the planets of the solar system.

**5. Supporting Evidence:**
While the Gaseous Hypothesis was initially proposed based on philosophical reasoning, subsequent scientific discoveries and observations have provided substantial evidence in support of this hypothesis. For example, the similarities in the orbital planes and directions of rotation of the planets are consistent with the idea that they formed from a spinning disk-like structure.

**Conclusion:**
In conclusion, the Gaseous Hypothesis, proposed by Immanuel Kant and further developed by Pierre-Simon Laplace, provides a plausible explanation for the formation of the solar system. It suggests that the solar nebula collapsed, flattened into a disk, and eventually formed the sun and the planets. While the Gaseous Hypothesis was proposed based on philosophical reasoning, it has gained scientific support through subsequent observations and discoveries.

According to the Collision Hypothesis proposed by Harold Jeffreys, there were three stars in the Universe before the origin of the solar system. primitive sun, the ‘companion star’ and the ‘intruding star’ which was moving towards ‘companion star’. 

Understanding the Pairs
To determine which pairs are correctly matched, let's analyze each statement:
1. Solar Eclipse - Occurs at full moon.
- Explanation: A solar eclipse occurs during a new moon when the moon is directly between the Earth and the Sun.
- Status: Incorrect.
2. Lunar Eclipse - Occurs at new moon.
- Explanation: A lunar eclipse occurs during a full moon when the Earth is between the Sun and the moon, causing the Earth's shadow to fall on the moon.
- Status: Incorrect.
3. Dawn - Period between sunset and complete darkness.
- Explanation: Dawn is the time period before sunrise when the sky begins to lighten, not after sunset. The period after sunset is referred to as dusk or twilight.
- Status: Incorrect.
4. Twilight - Period between sunrise and full daylight.
- Explanation: Twilight occurs both before sunrise (morning twilight) and after sunset (evening twilight). It is the time when the sky is partially illuminated but the sun is not yet visible.
- Status: Incorrect as described.
Conclusion
- All four pairs are incorrectly matched. Thus, the correct answer to the question is option 'A': No pair.
This analysis shows that understanding the definitions and timings of celestial events is critical, especially for competitive examinations like UPSC.