Olympiad Test: Earth And Universe -2 - Class 4 MCQ

Answer:
The biggest and smallest heavenly bodies among the sun, moon, and earth can be determined as follows:
1. Sun:
- The sun is the largest heavenly body in our solar system.
- It has a diameter of about 1.4 million kilometers, which is more than 100 times the diameter of the earth.
- It is primarily composed of hydrogen and helium gases.
- The sun is a source of heat and light for the solar system.
2. Earth:
- The earth is the third planet from the sun and the largest terrestrial planet in our solar system.
- It has a diameter of about 12,742 kilometers.
- The earth is primarily composed of rocks, minerals, and water.
- It is the only known planet to support life.
3. Moon:
- The moon is the natural satellite of the earth.
- It is the smallest heavenly body among the sun, moon, and earth.
- The moon has a diameter of about 3,474 kilometers, which is about one-fourth the diameter of the earth.
- It has a rocky surface with numerous impact craters.
Based on the above information, the answer is:
- The sun is the biggest heavenly body among the sun, moon, and earth.
- The moon is the smallest heavenly body among the sun, moon, and earth.

The correct answer is B: They are almost fixed in their places relative to each other.
Explanation:

• Stars are made up of gases: Stars are primarily composed of hydrogen and helium gases, with smaller amounts of other elements. These gases undergo nuclear fusion in their cores, which produces the energy that makes stars shine.


• Stars are much larger than planets in size: Stars are significantly larger than planets. They have a much greater mass and volume compared to planets, which allows them to generate the intense heat and pressure required for nuclear fusion.


• Stars twinkle because of irregular emission of light: When starlight passes through Earth's atmosphere, it gets distorted by the varying density of air pockets. This distortion causes the light to appear to twinkle or scintillate when observed from Earth.


• Stars are almost fixed in their places relative to each other: This statement is not true. While stars may appear relatively fixed when observed from Earth, they are actually in constant motion. Stars move within their galaxies and can even have their own proper motion, which is their apparent motion relative to the Sun.

Therefore, option B is the correct answer as it is not true in the case of stars.

To determine the pie chart that represents the fraction of the Earth that is not covered by water, we need to analyze each option and identify the one where the shaded part represents the fraction.
Let's analyze each option:
A: This pie chart shows a small shaded portion, indicating a small fraction of the Earth not covered by water.
B: This pie chart shows a large shaded portion, indicating a significant fraction of the Earth not covered by water.
C: This pie chart shows a medium shaded portion, indicating a moderate fraction of the Earth not covered by water.
D: This pie chart shows a large shaded portion, indicating a significant fraction of the Earth not covered by water.
Based on the analysis, option D has the largest shaded portion, indicating the largest fraction of the Earth not covered by water. Therefore, the correct answer is option D.
Answer: D

Introduction:
In this question, we are asked to identify which option is not a part of a solar system. Let's analyze each option and determine the correct answer.
Analysis:
To identify the option that is not a part of a solar system, we need to understand what a solar system consists of. A solar system typically includes a star (like the Sun), planets, moons, asteroids, and comets. Let's analyze each option to see if it fits this description:
- A: Earth:
- Earth is a planet and is a part of the solar system.

- B: Jupiter:
- Jupiter is the largest planet in our solar system and is a part of it.

- C: Moon:
- The Moon is a natural satellite of Earth and is a part of the solar system.

- D: Pole star:
- The Pole star, also known as Polaris, is a star located close to the celestial north pole. It is not a part of our solar system.
Conclusion:
Based on our analysis, the option that is not a part of a solar system is D: Pole star. All the other options - Earth, Jupiter, and Moon - are a part of the solar system.

In second image, we can see a nearly complete moon and in third its complete. So from all options and the pattern given, half moon will be the correct answer.

The correct statement regarding the planets is:

D: The distance of the planet from the sun determines its temperature

Explanation:
- The temperature of a planet is mainly determined by its distance from the sun, among other factors.
- The closer a planet is to the sun, the higher its temperature tends to be.
- Conversely, the farther a planet is from the sun, the lower its temperature tends to be.
- This is because the sun is the primary source of heat and light in our solar system, and its energy decreases with distance.
- The distance from the sun affects the amount of sunlight a planet receives, which in turn influences its temperature.
- Other factors such as the planet's atmosphere, composition, and internal heat sources also play a role in determining its temperature, but the distance from the sun is a significant factor.
- For example, Mercury, which is the closest planet to the sun, experiences extreme temperatures due to its proximity.
- On the other hand, Pluto, which is located much farther from the sun, has much colder temperatures.
- Therefore, the distance of a planet from the sun is a key determinant of its temperature.

Explanation:
The axis of the Earth is tilted at an angle, which is approximately 23.5 degrees. This tilt has significant effects on the seasons experienced in different hemispheres. Here's a detailed explanation of why the seasons in the Northern and Southern hemispheres can never be the same:
1. Tilted Axis: The Earth's axis is tilted relative to its orbit around the Sun. This means that as the Earth revolves around the Sun, different parts of the Earth receive varying amounts of sunlight throughout the year.
2. Sunlight Distribution: When the Northern hemisphere is tilted towards the Sun, it receives more direct sunlight, leading to warmer temperatures and longer days. This results in summer in the Northern hemisphere.
3. Opposite Seasons: At the same time, when the Northern hemisphere is experiencing summer, the Southern hemisphere is tilted away from the Sun. This causes the Southern hemisphere to receive less direct sunlight, resulting in cooler temperatures and shorter days. In the Southern hemisphere, it is winter when it is summer in the Northern hemisphere.
4. Equinoxes: Twice a year, during the equinoxes in March and September, the Earth's axis is not tilted towards or away from the Sun. During these times, both hemispheres receive equal amounts of sunlight, resulting in similar day and night lengths. These are the transitional periods between the seasons.
5. Tropics and Polar Regions: The tilt of the Earth's axis also affects the distribution of sunlight in the tropics and polar regions. The tropics near the equator experience relatively consistent temperatures throughout the year, while the polar regions have extreme seasonal variations due to their proximity to the poles.
In summary, the tilt of the Earth's axis is the primary reason why the seasons in the Northern and Southern hemispheres can never be the same. This tilt causes the hemispheres to receive different amounts of sunlight, leading to opposite seasons.

Identifying the Planet:
To determine which planet has 63 moons and a big red spot, we can analyze the characteristics of each option and match them to the given information.
Characteristics of the Planets:
A: Venus
- Venus does not have any moons.
- It does not have a big red spot.
B: Jupiter
- Jupiter has 79 known moons, which matches the given information of 63 moons.
- Jupiter is known for its Great Red Spot, a massive windstorm, which matches the description of a big red spot.
- Therefore, Jupiter is a possible match.
C: Uranus
- Uranus has 27 known moons, which does not match the given information of 63 moons.
- Uranus does not have a big red spot.
D: Saturn
- Saturn has 82 known moons, which does not match the given information of 63 moons.
- Saturn does not have a big red spot.
Conclusion:
Based on the analysis, only Jupiter matches the given characteristics of having 63 moons and a big red spot. Therefore, the answer is B: Jupiter.

Impact of the absence of Jupiter in the solar system:

• Saturn would be the biggest planet in the solar system: Jupiter is currently the largest planet in our solar system, with a mass more than twice that of all the other planets combined. If Jupiter did not exist, Saturn would take its place as the largest planet.


• Mars would be the coldest planet in the solar system: Jupiter plays a crucial role in the gravitational balance of the solar system. Its immense gravity helps to protect the inner planets, including Earth, from potential impacts by comets and asteroids. Without Jupiter's gravitational pull, more asteroids and comets would reach the inner solar system, increasing the chances of collisions. Mars, being one of the inner planets, would be more exposed to these impacts, making it the coldest planet due to a potential increase in dust and debris in its atmosphere.


• Life would grow on Venus: Jupiter's gravity also acts as a "cosmic vacuum cleaner," attracting and absorbing many potentially dangerous objects that could pose a threat to the inner planets. Without Jupiter's presence, Venus would be more vulnerable to impacts, potentially reducing its chances of supporting life.

Therefore, the correct answer is A: Saturn would be the biggest planet in the solar system.

What are comets made of?
Comets are composed of various materials, primarily dust and ice, with other elements and compounds also present. They are often referred to as "dirty snowballs" because of their composition. Here is a detailed explanation of the components found in comets:
Dust:
- Comets contain a significant amount of dust particles, which are made up of various minerals and rocky materials.
- The dust is believed to come from the debris left over from the formation of the solar system.
Ice:
- The ice in comets is mainly composed of frozen water, but it can also include other volatile substances such as carbon dioxide, methane, and ammonia.
- The ice remains frozen in the cold outer regions of the solar system until a comet's orbit brings it closer to the Sun.
Organic Compounds:
- Comets also contain organic compounds, which are carbon-based molecules. These compounds can include complex molecules like amino acids, the building blocks of proteins.
- Organic compounds found in comets provide valuable insights into the origins of life on Earth.
Gases:
- As a comet approaches the Sun, the heat causes the ice to vaporize, releasing gases into space.
- These gases form a glowing coma around the nucleus of the comet, which gives it a characteristic appearance.
Tail Formation:
- The release of gases and dust particles from the comet's nucleus creates a glowing coma and forms two distinct tails: a dust tail and an ion tail.
- The dust tail consists of tiny dust particles reflecting sunlight, while the ion tail is composed of charged particles influenced by the solar wind.
In summary, comets are primarily made up of dust and ice, along with organic compounds and gases. The combination of these materials creates the fascinating phenomena we observe when comets approach the Sun.