Test: Introduction to Earth & Universe- 1 - UPSC MCQ

1. Mercury - Smallest and closest to the sun: This pair is correctly matched. Mercury is indeed the smallest planet in the solar system and the closest to the sun.

2. Jupiter - Second largest planet with 12 satellites: This pair is incorrectly matched. Jupiter is the largest planet in the solar system, not the second largest. It has more than 12 satellites; in fact, it has at least 79 known moons.

3. Uranus - Orbits around the sun in a clockwise direction from east to west: This pair is correctly matched. Uranus is unique in that it rotates on its side, and its rotation is from east to west, which is opposite to the direction of most of the other planets.

4. Neptune - Natural satellite is the moon: This pair is incorrectly matched. Neptune does not have the moon as its natural satellite. Neptune has 14 known moons, with Triton being the largest.

Thus, only pairs 1 and 3 are correctly matched.

1. Solar Eclipse - Occurs at full moon.
Incorrect. A solar eclipse occurs when the moon comes exactly between the Earth and the Sun, which happens at new moon, not full moon.

2. Lunar Eclipse - Occurs at new moon.
Incorrect. A lunar eclipse occurs when the Earth comes exactly between the Sun and the Moon, which happens at full moon, not new moon.

3. Dawn - Period between sunset and complete darkness.
Incorrect. Dawn is the period between sunrise and full daylight, not between sunset and complete darkness. The correct term for the period between sunset and complete darkness is twilight.

4. Twilight - Period between sunrise and full daylight.
Incorrect. Twilight refers to the period between sunset and complete darkness, not as the period between sunrise and full daylight. In this context, it is incorrectly matched.

Only the fourth pair is correctly matched, making the answer Option A: No pair.

Statement-I is correct as the Earth does indeed rotate around its own axis from west to east in an anticlockwise direction. This rotation causes the phenomena of day and night.
Statement-II is also correct as the velocity of the Earth's rotation does decrease from the equator to the poles. This is due to the Earth being an oblate spheroid, causing a greater circumference at the equator than at the poles. The decrease in velocity from the equator to the poles is related to the conservation of angular momentum.
While both statements are correct, Statement-II does not directly explain Statement-I. The Earth's rotation direction and the change in velocity from equator to poles are related phenomena but do not explain each other in a causal or explanatory manner. Hence, option (b) is the correct answer.

The Earth is not a perfect sphere but an oblate spheroid, meaning it is slightly flattened at the poles and bulging at the equator. This shape is due to the Earth's rotation, which causes a centrifugal force that flattens it at the poles and bulges it at the equator. This shape is essential in understanding various phenomena on Earth, such as gravity, climate patterns, and the distribution of land and water on the planet.

Let's analyze each statement:

1. Venus is the second closest planet to the sun and is twice the distance away from the sun compared to Mercury.

- This statement is correct. Venus is indeed the second planet from the sun, and it is approximately twice the distance from the sun compared to Mercury.

2. Jupiter, the largest planet in the solar system, has a surface that is very cold due to its gaseous composition.

- This statement is correct. Jupiter is the largest planet in the solar system, and its surface is very cold due to its composition of gases such as hydrogen, helium, and methane.

3. Uranus orbits around the sun in a clockwise direction from east to west.

- This statement is correct. Uranus is unique in that it has a retrograde rotation, meaning it orbits the sun in a clockwise direction from east to west.

All three statements are correct.

Thus, the correct answer is Option D: 1, 2 and 3.

Statement-I is correct because during the Summer Solstice, when the Earth's axis is tilted at its maximum of approximately 23.5 degrees towards the Sun in the Northern Hemisphere, the Tropic of Cancer receives 14 hours of daylight. This is when the Sun's rays fall vertically on the Tropic of Cancer.
Statement-II is also correct as the Equator generally receives approximately 12 hours of daylight throughout the year due to its position relative to the Earth's tilt and its location at the center of the Earth's latitudinal range.
Therefore, both statements are correct, and Statement-II explains why the Tropic of Cancer receives 14 hours of daylight during the Summer Solstice.

1. Tropic of Cancer - 23.5° North of Equator: Correct. This parallel is indeed located at 23.5° north of the equator.

2. Tropic of Capricorn - 23.5° South of Equator: Correct. This parallel is positioned at 23.5° south of the equator.

3. Arctic Circle - 66.5° South of Equator: Incorrect. The Arctic Circle is located at 66.5° north of the equator.

4. Antarctic Circle - 66.5° North of Equator: Incorrect. The Antarctic Circle is situated at 66.5° south of the equator.

Thus, only the first two pairs are correctly matched.

- Statement-I mentions that the light from the nearest star takes around 4 years to reach Earth, which is false. This statement incorrectly implies that the light from the nearest star takes 4 years to reach Earth, while in reality, the distance covered by light from the nearest star would be much shorter, given the proximity of some stars to Earth.
- Statement-II correctly describes Neptune as a much colder planet compared to Earth due to its greater distance from the Sun. Neptune is indeed much colder than Earth because it is located much farther away from the Sun and receives significantly less solar energy.
Therefore, Statement-I is inaccurate, while Statement-II is correct, making option (d) the correct answer.

The Earth moves in space by rotating on its own axis from west to east every 24 hours, causing the phenomena of day and night. Additionally, it revolves around the sun in an elliptical orbit every 365.25 days, resulting in the changing seasons and marking the passage of a year. These two motions, rotation, and revolution, are fundamental to various natural phenomena on Earth, including the length of days, seasonal variations, and the distribution of sunlight across the planet.

Statement 1: The Earth's axis is indeed inclined at 23.5° to the perpendicular to the plane of the ecliptic. This inclination is responsible for the seasonal changes experienced on Earth. Since this is a factual statement about Earth's axial tilt, it is correct.

Statement 2: The Tropic of Cancer does not receive vertical sunrays at the winter solstice. Instead, it receives vertical sunrays at the summer solstice, when the Northern Hemisphere is tilted towards the sun. During the winter solstice, the Tropic of Capricorn receives vertical sunrays as the Southern Hemisphere is tilted towards the sun. Therefore, this statement is incorrect.

Statement 3: The length of latitudes, or parallels, does indeed decrease from the equator to the poles. This is because the circumference of the Earth is greatest at the equator and gradually reduces towards the poles. Hence, this statement is correct.

Given the correctness of statements 1 and 3, the correct answer is:

Option C: 1 and 3 Only

1. Statement 1 is correct: During the winter solstice, the Earth's axis indeed leans at a maximum of 23.5 degrees in the southern hemisphere towards the sun. This is the fundamental definition of the winter solstice, which occurs around December 21/22.

2. Statement 2 is incorrect: On the winter solstice, the sun's rays fall vertically at the Tropic of Capricorn, not the Tropic of Cancer. The Tropic of Cancer is significant during the summer solstice in the northern hemisphere.

3. Statement 3 is incorrect: Between the Antarctic Circle and the South Pole, during the winter solstice, this region experiences 24 hours of night 

Therefore, the correct option is A. 

The correct answer is:

3. Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I.

Here's why:

• Statement-I is correct. During summer, the sun's rays are more direct (overhead), concentrating their heat on a smaller area. This results in higher temperatures as the energy is more focused.

• Statement-II is also correct. In winter, the sun's rays are more oblique, meaning they spread over a larger area and pass through more of the atmosphere. This causes less direct heating and more heat absorption by the atmosphere, resulting in lower temperatures.

However, Statement-II does not directly explain Statement-I. Instead, it describes the general principle of why temperatures are lower in winter compared to summer.

During the winter solstice at the Tropic of Capricorn, the duration of daylight is approximately 14 hours. This phenomenon occurs because the Earth's axis is inclined towards the sun in the Southern Hemisphere, leading to longer daylight hours in this region. The tilt of the Earth's axis causes variations in the lengths of days and nights throughout the year, influencing seasonal changes and the distribution of sunlight on the Earth's surface.

- Statement 1 is correct. Dawn is indeed the brief period between sunrise and full daylight. During dawn, the earth receives diffused or refracted light from the sun while it is still below the horizon.

- Statement 2 is correct. Twilight is the period between sunset and complete darkness. Similar to dawn, it is caused by the earth receiving diffused or refracted light from the sun when it is below the horizon.

- Statement 3 is incorrect. The duration of twilight is not the same at the equator and the poles. At the equator, the sun rises and sets in a vertical path, resulting in a shorter duration of refracted light. In contrast, at the poles, the sun rises and sets in an oblique path, resulting in a much longer period of twilight.

Therefore, the correct answer is Option B.

Let's analyze each pair to determine if they are correctly matched:

1. **Winter Solstice: Day lasts for 6 months at the South Pole**
   - This statement is correct. During the Winter Solstice (around December 21), the South Pole experiences continuous daylight for about six months.

2. **Equinoxes: Sun's rays are vertical at the Tropic of Cancer on 21 March and 21 September**
   - This statement is incorrect. During the Equinoxes (around March 21 and September 23), the Sun's rays are vertical at the Equator, not at the Tropic of Cancer.

3. **Summer Solstice: Sun's rays fall vertically at the Tropic of Capricorn on 21 June**
   - This statement is incorrect. During the Summer Solstice (around June 21), the Sun's rays fall vertically at the Tropic of Cancer, not the Tropic of Capricorn.

4. **Seasonal Changes: Longer days in summer lead to higher temperatures**
   - This statement is correct. Longer days in summer result in more hours of sunlight, which leads to higher temperatures.

Based on the analysis:

- Pair 1 is correctly matched.
- Pair 2 is incorrectly matched.
- Pair 3 is incorrectly matched.
- Pair 4 is correctly matched.

Therefore, only two pairs (1 and 4) are correctly matched.

The correct answer is:

**1. Only two pairs**