All questions of Topic-wise and Full- length Prelims Previous Year Questions for UPSC CSE Exam

Yes, the answer is venus because this planet resembles our mother earth in its size, mass, proximity to the sun, bulk composition.

Option 'A' Galileo Galilei

Satpura..

Jupiter as radius of its orbit is largest among four....

Since 2006, per the International Astronomical Union's planetary criteria, Pluto isn't considered a planet because it hasn't cleared the neighborhood around its orbit of other objects. However, it does meet IAU's criteria for what constitutes a dwarf planet.  Pluto was discovered by Clyde Tombaugh in 1930. Pluto has been given the number 134340.

Pachmarhi:-

In the heart of our country, Madhya Pradesh, there exists a hill station which happens to be the only hill station present in the state. Pachmarhi, also known as 'Satpura ki Rani' or 'The Queen of Satpura' sits perfectly surrounded by nature, history, and mythology amidst the Satpura range.

The Earth is the densest of all planets in the Solar System.  The predominant element in the composition of the Earth is Iron (36 %) and in the Earth’s crust is oxygen (45 %).  The Sun contains 99 % of the mass of the solar system.  The diameter of the sun is 109 times that of the Earth.

Jupiter

61.42 billion km²

Explanation:

When an observer sees the stars rising perpendicular to the horizon, it means that he is located at the Earth's equator. This is because the Earth's equator is the only location where the celestial equator (the projection of the Earth's equator onto the celestial sphere) is perpendicular to the horizon.

The celestial equator is an imaginary line that circles the celestial sphere, and it is the projection of the Earth's equator onto the sky. The celestial equator is also the reference point for measuring the declination of celestial objects, which is similar to the latitude on Earth.

When an observer is located at the Earth's equator, the celestial equator appears to be perpendicular to the horizon because the observer's latitude and the celestial equator are the same. This means that the observer is looking directly at the celestial equator, which is why the stars appear to be rising perpendicular to the horizon.

In contrast, at the Tropic of Cancer, the South Pole, or the North Pole, the celestial equator is not perpendicular to the horizon, and the stars do not appear to rise perpendicular to the horizon.

Therefore, we can conclude that if an observer sees the stars rising perpendicular to the horizon, he is located on the Earth's equator.

Venus is the second brightest natural object in the night sky after the moon.

Answer:

Introduction:
In our solar system, there are several planets that have moons orbiting around them. However, there is one planet that does not have any moons. This planet is Mercury.

Explanation:
Here is a detailed explanation of why Mercury does not have any moons:

1. Size and proximity to the Sun:
Mercury is the smallest planet in our solar system and is also the closest planet to the Sun. Its small size and close proximity to the Sun make it difficult for the planet to capture and hold onto any moons. The gravitational pull of the Sun is so strong that it can easily disrupt the orbit of any moon that comes close to Mercury.

2. Lack of an atmosphere:
Another factor that contributes to Mercury not having any moons is its lack of a substantial atmosphere. The presence of an atmosphere can help in capturing and stabilizing moons. However, Mercury has a very thin and tenuous atmosphere, which is not sufficient to hold onto any moons.

3. High temperatures:
Mercury's proximity to the Sun also means that it experiences extremely high temperatures. The average surface temperature on Mercury can reach up to 800 degrees Fahrenheit (430 degrees Celsius). These extreme temperatures make it inhospitable for any moons to exist.

4. Closest approach to Earth:
Mercury's proximity to Earth also means that it has been extensively observed and studied. Scientists have not detected any moons around Mercury despite using advanced telescopes and space probes. This further confirms that Mercury does not have any moons.

Conclusion:
In conclusion, Mercury is the planet in our solar system that does not have any moons. Its small size, close proximity to the Sun, lack of atmosphere, high temperatures, and extensive observations all contribute to the absence of moons around Mercury.

Sorry, but I'm not able to generate a response based on the given information. Could you please provide me with the options or additional context?

The Himalayas are a range of mountains in Asia that extend over 2,400 km from the Indus River in Pakistan to the Brahmaputra River in northeastern India. They are considered to be fold mountains.

Explanation:
Fold mountains are formed by the folding of layers of rock due to the movement of tectonic plates. The Himalayas were formed by the collision of the Indian Plate and the Eurasian Plate, which caused the rocks to fold and uplift, forming the highest mountain range in the world.

Features of Fold Mountains:
• Fold mountains are the most common type of mountains on Earth.
• They are formed by the compression of tectonic plates.
• They are characterized by steep slopes, sharp ridges, and deep valleys.
• They are usually found in long chains or ranges.
• Fold mountains are rich in mineral resources like coal, oil, and gas.

Conclusion:
The Himalayas are a prime example of fold mountains, formed due to the collision of two tectonic plates. They are characterized by steep slopes, sharp ridges, and deep valleys, and are rich in mineral resources.

Answer:

To determine which planet has its orbit closest to the Sun, we need to understand the concept of the planets' distances from the Sun. Let's examine the distances of the given planets from the Sun:

- Venus: Venus is the second planet from the Sun, with an average distance of about 108 million kilometers.
- Mars: Mars is the fourth planet from the Sun, with an average distance of about 228 million kilometers.
- Jupiter: Jupiter is the fifth planet from the Sun, with an average distance of about 778 million kilometers.
- Uranus: Uranus is the seventh planet from the Sun, with an average distance of about 2.9 billion kilometers.

Based on the distances provided, we can see that Venus has the shortest average distance from the Sun among the given planets. Therefore, the correct answer is option 'A' - Venus.

Summary:
- Venus has the shortest average distance from the Sun among the given planets.
- Mars, Jupiter, and Uranus have greater average distances from the Sun compared to Venus.
- The order of the planets from the Sun in terms of increasing distance is Venus, Mars, Jupiter, and Uranus.

The Red Planet: Mars

Mars is often referred to as the "red planet" due to its reddish appearance. Let's explore why Mars is called the red planet.

1. Appearance:
Mars appears reddish in the night sky, which is why it earned the nickname "red planet." When observed from Earth, Mars has a distinctive reddish hue, making it easily recognizable among the other celestial bodies.

2. Composition:
The red color of Mars is attributed to its unique composition. The planet's surface is covered in iron oxide, also known as rust. Iron oxide gives Mars its reddish appearance, similar to the color of rusted iron. The iron oxide particles reflect and scatter sunlight, creating the red hue that we observe.

3. Iron Oxide:
Iron oxide is a compound made up of iron and oxygen. The presence of iron oxide on Mars is believed to be a result of various geological processes, including volcanic activity, weathering, and erosion. Over time, these processes have led to the accumulation of iron oxide on the planet's surface.

4. Martian Soil:
The soil on Mars, known as regolith, contains a significant amount of iron oxide. The regolith is composed of loose rocks, dust, and soil-like materials. The iron oxide content in the Martian soil contributes to the planet's overall red color.

5. Thin Atmosphere:
Mars has a thin atmosphere compared to Earth, which also affects its appearance. The atmosphere of Mars is primarily composed of carbon dioxide, with traces of nitrogen and argon. The thin atmosphere allows more sunlight to penetrate and interact with the iron oxide particles on the surface, intensifying the red color.

Conclusion:
Mars is called the red planet because of its reddish appearance, mainly due to the presence of iron oxide on its surface. The iron oxide particles reflect and scatter sunlight, creating a distinct red hue. Understanding the composition and appearance of Mars helps scientists study the planet's geological history and potential for supporting life.

Venus is a exception, as its proximity to the sun and dense atmosphere makes it our solar system's hottest planet.

Black holes are stars which have contracted so much that they have developed Super density.  Their Gravitational pull is so strong that even the light of radiation produced by them cannot escape.  They cannot be seen with the help of optical Telescope.  It is the smallest and the densest object in the Universe. 

Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars and Mercury are the planetary arrangement in terms of surface area.

The Surface Temperature of the Sun

The surface temperature of the Sun is estimated to be approximately 6000 degree Celsius (or 10,800 degree Fahrenheit). This estimate is based on extensive scientific research and observation of the Sun's spectrum and radiation.

Understanding the Sun's Temperature

1. Solar Spectrum: Scientists have studied the spectrum of sunlight, which is the distribution of its electromagnetic radiation across different wavelengths. By analyzing this spectrum, they can determine the temperature of the Sun's surface.

2. Black Body Radiation: The Sun is often considered as a black body radiator, which means it emits radiation across a wide range of wavelengths. The intensity of this radiation depends on the temperature of the object. By comparing the Sun's radiation with the radiation emitted by objects of known temperatures, scientists can estimate the Sun's surface temperature.

3. Color Temperature: The color of an object is related to its temperature. For example, when an object is heated, it starts to emit light, and the color of the light changes as the temperature increases. By examining the color of the Sun's light, scientists can estimate its surface temperature.

Estimating the Surface Temperature

1. Stellar Spectral Classification: Scientists classify stars based on their spectral characteristics. The Sun is classified as a G-type main-sequence star, also known as a yellow dwarf. This classification provides an initial estimate of its surface temperature.

2. Temperature Calculation: By analyzing the sunlight spectrum and using mathematical models, scientists calculate the effective temperature of the Sun. The effective temperature is the temperature of an idealized black body that radiates the same amount of energy as the Sun.

3. Observational Data: Scientists also use observational data from space-based telescopes and satellites to gather information about the Sun's temperature. These observations provide valuable data on the Sun's surface temperature and help refine the estimates.

The Final Estimate

Based on these methods and observations, the surface temperature of the Sun is estimated to be around 6000 degree Celsius (10,800 degree Fahrenheit). This temperature is high enough to sustain the nuclear fusion reactions that occur in the Sun's core and produce the immense amount of energy radiated by the Sun.

It is important to note that the Sun's temperature is not constant throughout its layers. The temperature increases from the surface towards the core, reaching millions of degrees Celsius in the core region where nuclear fusion takes place.

In conclusion, the estimated surface temperature of the Sun is approximately 6000 degree Celsius (10,800 degree Fahrenheit). This estimate is based on the analysis of the Sun's spectrum, radiation, and observational data from space-based telescopes.

The water cycle also known as the hydrological cycle, describes the continuous movement of water on, above and below the surface of the Earth.

Assertion (A): Existence of human life on Venus is highly improbable.
Reason (R): Venus has an extremely high level of carbon dioxide in its atmosphere.

The correct answer is option A, where both the Assertion and Reason are correct and the Reason is the correct explanation for the Assertion.

Explanation:

Assertion (A): Existence of human life on Venus is highly improbable.
Reason (R): Venus has an extremely high level of carbon dioxide in its atmosphere.

To understand why option A is the correct answer, let's examine the assertion and reason individually.

Assertion (A): Existence of human life on Venus is highly improbable.
Venus, the second planet from the Sun, is known for its extreme conditions that make it inhospitable for human life. Some of the key factors that contribute to the improbability of human life on Venus are:

1. Extreme temperature: Venus has a surface temperature that averages around 900 degrees Fahrenheit (475 degrees Celsius), which is hotter than the surface of Mercury, even though Mercury is closer to the Sun. Such high temperatures would be detrimental to human life as it would be impossible to survive without protection.

2. Atmospheric pressure: Venus has an extremely dense atmosphere with a pressure about 92 times greater than Earth's atmospheric pressure at sea level. This high pressure can crush any structure and would be highly damaging to human bodies.

3. Lack of oxygen: Venus has a predominantly carbon dioxide atmosphere, with only trace amounts of oxygen. Oxygen is vital for human respiration, and the absence of sufficient oxygen would make it impossible for humans to survive.

4. Acidic atmosphere: Venus has a thick atmosphere comprised mainly of carbon dioxide, with clouds of sulfuric acid. The presence of sulfuric acid in the atmosphere makes the environment highly corrosive and unsuitable for human life.

Considering these extreme conditions, it is highly improbable for human life to exist on Venus without extensive technological advancements.

Reason (R): Venus has an extremely high level of carbon dioxide in its atmosphere.
The reason provided in the question is that Venus has an extremely high level of carbon dioxide in its atmosphere. This is indeed true, as Venus has a carbon dioxide-dominated atmosphere with a concentration about 96% by volume. The high levels of carbon dioxide contribute to the greenhouse effect on Venus, trapping heat and leading to the planet's scorching temperatures.

The presence of such high levels of carbon dioxide in the atmosphere further reinforces the assertion that human life on Venus is highly improbable. The excessive heat, along with the lack of oxygen and the corrosive nature of the atmosphere, makes it inhospitable for humans.

Therefore, option A is the correct answer as both the assertion and reason are correct, and the reason correctly explains why the existence of human life on Venus is highly improbable.

The average distance between the sun and the Earth is known as Astronomical Unit (1AU= 150 x 10⁶ kms)