Important Questions Test: Stars And The Solar System - UPSC MCQ

Venus can often be seen within a few hours after sunset or before sunrises as the brightest object in the sky. It looks like a very bright star. Venus is the brightest planet in the solar system.

Nearest planet of the sun is Mercury
Explanation:
- The question asks for the nearest planet to the sun, and the correct answer is Mercury.
- Mercury is the closest planet to the sun in our solar system.
- It orbits the sun at an average distance of about 36 million miles (58 million kilometers).
- The proximity to the sun makes Mercury the hottest planet, with surface temperatures reaching up to 800 degrees Fahrenheit (430 degrees Celsius) during the day.
- Mercury is also the smallest planet in our solar system, with a diameter of about 3,032 miles (4,879 kilometers).
- It has a thin atmosphere and no moons.
- Due to its proximity to the sun, Mercury has a short year, completing one orbit around the sun in just 88 Earth days.
- It also has a slow rotation, taking about 59 Earth days to complete one rotation on its axis.
- The Mariner 10 and MESSENGER missions have provided valuable information about Mercury's surface and composition.
- In conclusion, the nearest planet to the sun is Mercury.

One of the planets where life exists:
- Earth: Earth is the only known planet where life exists. It is the third planet from the Sun and is home to a diverse range of living organisms, including plants, animals, and humans. Earth has a suitable atmosphere, water in liquid form, and a moderate temperature range, which are essential for supporting life.
- Moon: The Moon is not a planet and does not support life. It is Earth's natural satellite and has a harsh environment with no atmosphere or liquid water.
- Jupiter: Jupiter is a gas giant and not a suitable environment for life as we know it. It has a thick atmosphere composed mainly of hydrogen and helium, with no solid surface.
- None: Apart from Earth, there is currently no scientific evidence to suggest that life exists on any other planet in our solar system or beyond.
In conclusion, the only planet where life is known to exist is Earth. Other celestial bodies such as the Moon and Jupiter do not have the necessary conditions to support life.

Saturn is pale gold. White ammonia haze covers the whole planet and partially obscures the redder clouds below.

The correct option is A.
Neptune is the eighth and farthest-known Solar planet from the Sun. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth, slightly more massive than its near-twin Uranus.

The correct answer is B as the first orbit on the earth is mars.

Introduction:
The question asks for the largest planet among Mercury, Mars, Jupiter, and Saturn. Let's analyze each option and determine the correct answer.
Analysis:
To determine the largest planet, we need to consider the size of each planet. Here's a comparison of the four options:
- Mercury: Mercury is the smallest planet in our solar system. It has a diameter of approximately 4,879 kilometers.
- Mars: Mars is the fourth planet from the Sun and has a diameter of about 6,779 kilometers.
- Jupiter: Jupiter is the largest planet in our solar system. It has a diameter of approximately 139,820 kilometers, making it significantly larger than Mercury and Mars.
- Saturn: Saturn is the sixth planet from the Sun and has a diameter of about 116,460 kilometers. Although it is large, it is not as big as Jupiter.
Conclusion:
Based on the analysis, we can conclude that the correct answer is Jupiter (Option C). It is the largest planet among the given options, with a diameter of approximately 139,820 kilometers.

The gap between the orbit of Mars and Jupiter is called:
Asteroid Belt
- The correct answer is A: Asteroid.
- The gap between the orbit of Mars and Jupiter is known as the Asteroid Belt.
- The Asteroid Belt is a region of space located between the orbits of Mars and Jupiter, where numerous small rocky objects, called asteroids, are found.
Asteroids
- Asteroids are rocky, airless remnants left over from the early formation of our solar system.
- They can vary in size from small boulders to objects that are hundreds of kilometers in diameter.
- Most asteroids are irregularly shaped and can have craters or grooves on their surfaces.
Asteroid Belt Characteristics
- The Asteroid Belt is estimated to contain millions of asteroids.
- The total mass of all the asteroids in the belt is less than that of Earth's moon.
- The asteroids in the belt are primarily composed of rock and metal.
Origin of Asteroid Belt
- The Asteroid Belt is believed to be the result of a gravitational perturbation caused by the massive planet Jupiter.
- Jupiter's strong gravitational pull prevented the formation of a planet in the gap between Mars and Jupiter.
- Instead, the material in this region coalesced into smaller objects, forming the Asteroid Belt.
Exploration of the Asteroid Belt
- Several spacecraft have been sent to explore the Asteroid Belt, including NASA's Dawn mission, which visited the two largest asteroids, Vesta and Ceres.
- These missions have provided valuable insights into the composition and formation of asteroids.
In conclusion, the gap between the orbit of Mars and Jupiter is known as the Asteroid Belt. It is a region in space where numerous small rocky objects, called asteroids, are found. The Asteroid Belt is believed to have formed due to the gravitational influence of Jupiter and has been explored by various spacecraft to study its composition and origins.

The correct answer is B as  stars moves from east to west

The earth's axis of rotation is tilted about 23.5 degrees compared to the plane of the earth's orbit around the sun. The earth's tilt is responsible for the seasons we experience.

Uranus is the seventh planet in our solar system . it has a very large distance from sun and is extremely cold.

False
Explanation:
There are only eight planets in our solar system, not nine. In 2006, the International Astronomical Union (IAU) redefined the definition of a planet, and as a result, Pluto was reclassified as a "dwarf planet." Therefore, the correct answer is false.
Here are the key points to support the answer:
1. The IAU's definition of a planet requires an object to meet three criteria:
- It must orbit the Sun.
- It must be spherical in shape due to its own gravity.
- It must have cleared its orbit of other debris.
2. Pluto does not meet the third criterion because it shares its orbit with other objects in the Kuiper Belt. Therefore, it was reclassified as a dwarf planet.
3. The eight planets in our solar system, in order of their distance from the Sun, are:
- Mercury
- Venus
- Earth
- Mars
- Jupiter
- Saturn
- Uranus
- Neptune
4. While Pluto is no longer considered a planet, it remains an interesting celestial object and is part of the Kuiper Belt, a region beyond Neptune populated by icy bodies.
In conclusion, there are eight planets in our solar system, not nine. Pluto is now classified as a dwarf planet.

The hottest stars have surface temperature of 50,000  Kelvin degrees. The sun surface is only ~5800 Kelvin degrees, which means that there are hotter stars than the sun.

Answer:
The statement "Jupiter is the smallest planet" is false.
Explanation:
Here's why Jupiter is not the smallest planet:
1. Size of Jupiter: Jupiter is the largest planet in our solar system. It has a diameter of about 139,820 kilometers (86,881 miles) which is more than 11 times the diameter of Earth.
2. Comparison with other planets: There are smaller planets in our solar system compared to Jupiter. Here are some examples:
- Mercury: Mercury is the smallest planet in our solar system. It has a diameter of about 4,879 kilometers (3,032 miles), which is less than half the diameter of Earth.
- Mars: Mars is also smaller than Jupiter. It has a diameter of about 6,779 kilometers (4,212 miles).
- Venus: Venus is slightly smaller than Earth but still larger than Jupiter. It has a diameter of about 12,104 kilometers (7,521 miles).
3. Gas giant: Jupiter is a gas giant planet, primarily composed of hydrogen and helium. Its size and composition make it significantly larger than the rocky planets like Earth, Mars, and Mercury.
In conclusion, Jupiter is the largest planet in our solar system and not the smallest. Mercury holds the title for being the smallest planet.

Stars, including the Sun, emit light because deep down at the core of a star there are nuclear fusion reactions happening. These reactions produce an enormous amount of heat and light. Most objects in space, other than  stars, reflect light. For example, planets like Venus, Mars , Jupiter  and saturn  all reflect light.

The full moon phase occurs when the moon is on the opposite side of the earth from the sun, called opposition. A waning gibbous moon occurs when more than half of the lit portion of the moon can be seen and the shape decreases in size from one day to the next.

We see constellations at different times of the year- spring, summer, fall, and winter. This occurs because the Earth is orbiting the sun. But in summer, we see the opposite ( we see Scorpius at night and Orion  is in the sky during the day) . This is why you cannot see orion or any one constellation all year long.

Mercury is the closest planet to earth- in fact, its the closest planet to every other planet. Mercury is closer to earth almost 50 %  of the time, with the remainder split between Mars and Venus.
So, the given statement is correct.

There are 8 planets in the solar system:-  Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. 
Pluto, a dwarf planet, was classified as one of the solar system planets. However, it now considered to be one of the largest known members of the Kuiper Belt - a collection of icy bodies on the outer fringes of the solar system.

Jupiter is the largest planet in the solar system. The largest planet in the solar system, the gas giant Jupiter approximately 318 times as massive as earth. If the mass of all of the other planets in the solar system were combined into one " Super planet", Jupiter would still be two and a half times as large.