All questions of The Earth for Grade 6 Exam

Ans c

Option B, Revolution

Due to gravitational force on moon

Our Solar System is located in the Milky Way Galaxy.

Ascending Order of Size of Earth, Moon, and Sun

The size of celestial bodies is measured in terms of their diameter. The diameter of the Earth, Moon, and Sun are as follows:

- Earth: 12,742 km
- Moon: 3,474 km
- Sun: 1,391,000 km

To arrange them in increasing order of size, we need to start with the smallest and move towards the largest.

1. The Moon
The Moon is the smallest of the three celestial bodies. It has a diameter of 3,474 km.

2. The Earth
The Earth is the second largest of the three celestial bodies. It has a diameter of 12,742 km.

3. The Sun
The Sun is the largest of the three celestial bodies. It has a diameter of 1,391,000 km.

Therefore, the correct order of the size of Earth, Moon, and Sun in ascending order is:

The Moon - The Earth - The Sun (Option D)

Explanation:


When a ship sails away from the shore, it appears to go down slowly and gradually. This happens because of the curvature of the Earth's surface. The Earth is round-shaped, and as the ship moves away from the shore, its bottom part disappears first, followed by the middle part, and eventually the top part. This happens because the Earth's surface curves downwards, and eventually, the ship goes below the horizon line.

Proof:


To understand this phenomenon, we can conduct a simple experiment. Take a basketball or any other round object and place a small object on top of it. Now, move the small object away from the center of the basketball. As you move it away, the object will appear to go down, and eventually, it will disappear from sight. This happens because the surface of the basketball curves downwards, just like the surface of the Earth.

Conclusion:


This observation proves that the Earth is round-shaped. If the Earth were flat, the entire ship would remain visible until it went out of sight. However, since the Earth is round, the curvature of its surface causes the ship to disappear gradually as it moves away from the shore.

Explanation:

The full moon day is also known as "Purnima" in Hindu mythology. It is one of the most important and auspicious days in the lunar calendar. Purnima is derived from the Sanskrit word "Purnamasi" which means "full moon."

Significance of Purnima:
Purnima holds great significance in various cultures and religions. It is believed to be a time of spiritual growth, enlightenment, and divine blessings. Many religious rituals and festivals are celebrated on this day.

Importance in Hinduism:
In Hinduism, Purnima is considered sacred and is associated with various deities and celestial beings. It is believed that on this day, the moon is in its full glory and radiates positive energy. Some of the major Hindu festivals celebrated on Purnima are:
- Raksha Bandhan: A festival celebrating the bond between brothers and sisters.
- Guru Purnima: A day to honor and express gratitude towards spiritual and academic teachers.
- Sharad Purnima: The full moon day in the month of Ashwin, celebrated with dance and music.

Other Cultures and Beliefs:
Purnima is not just significant in Hinduism but also in other cultures and beliefs. Some examples include:
- Buddhist Purnima: Celebrated as Vesak or Buddha Purnima, commemorating the birth, enlightenment, and death of Gautam Buddha.
- Jain Purnima: Celebrated as Paryushana, a time of self-reflection and spiritual purification for Jains.
- Chinese Purnima: Celebrated as Mid-Autumn Festival, where families gather to admire the full moon and enjoy mooncakes.

Conclusion:
The full moon day is known as Purnima and holds immense cultural, religious, and spiritual significance. It is a time for celebration, reflection, and seeking blessings. Purnima is a beautiful phenomenon observed by people worldwide, connecting them with nature and the celestial realm.

Stars emit their own light through nuclear fusion, while planets do not emit their own light and only reflect the Sun's light.

Excessive artificial light from urban areas causes light pollution, making it difficult to see stars.

Orion is easily identified by the three stars in a row that form Orion's Belt.

Earth looks round, like a ball, but is slightly flat at the top and bottom.

It is a bit wider in the middle, like an orange.

Photos from space confirm this shape.

Understanding Comets
Comets are fascinating celestial objects that capture our imagination with their stunning appearances and unique characteristics.
Composition of Comets
- Comets are primarily made up of:
- Dust
- Ice
- Gases
These materials are often described as "dirty snowballs" because of their icy cores mixed with dust.
Formation of the Coma
- As a comet approaches the Sun, the heat causes the ice to vaporize.
- This process creates a glowing envelope of gas and dust around the nucleus called the coma.
- The coma can be quite large, sometimes extending thousands of kilometers into space.
The Tail of the Comet
- The solar wind and radiation pressure from the Sun push the gas and dust away from the coma, forming a tail.
- This tail can stretch millions of kilometers and is always directed away from the Sun, regardless of the comet's direction of travel.
Differences from Other Celestial Objects
- Unlike asteroids, which are rocky and mostly found in the asteroid belt, comets are icy bodies that originate from the outer regions of the solar system.
- Moons are natural satellites orbiting planets, while dwarf planets are celestial bodies that are not classified as full-fledged planets but are larger than asteroids.
In summary, the correct answer is C) Comet, as it is the only object in the options that forms a coma and tail when near the Sun due to its unique composition of dust, ice, and gases.

Earth has fresh air to breathe.

It has water to drink and use.

Land is needed to grow food and build homes.

The shadow cast by the Earth on the Moon during an eclipse is round shaped.

Eclipses occur when one celestial body moves into the shadow of another. In the case of a lunar eclipse, the Earth moves between the Sun and the Moon, casting a shadow on the Moon's surface. This shadow is responsible for the darkening or reddening of the Moon during an eclipse.

1. The Earth's Shadow
The Earth's shadow has two parts: the penumbra and the umbra. The penumbra is the outer part of the shadow and is not completely dark. It gradually gets darker towards the center, where the umbra begins. The umbra is the inner part of the shadow and is completely dark.

2. Shape of the Earth's Shadow
The shape of the Earth's shadow is round. This is because the Earth is a spherical shape, and when it blocks the Sun's light, it creates a circular shadow. The curvature of the Earth determines the shape of the shadow.

3. Projection onto the Moon
When the Earth casts its shadow onto the Moon during a lunar eclipse, the round shape of the shadow is projected onto the Moon's surface. This is why during a total lunar eclipse, we see a perfectly round shadow covering the Moon. The shadow may appear slightly distorted due to the irregularities on the Moon's surface, but overall, it retains its round shape.

4. Variation in Shadow Size
The size of the Earth's shadow on the Moon can vary during different stages of an eclipse. At the beginning and end of a lunar eclipse, when the Moon is partially in the Earth's shadow, the shadow may appear slightly elongated. However, during a total lunar eclipse, when the Moon is fully within the umbra, the shadow takes on a more distinct and round shape.

In conclusion, the shadow cast by the Earth on the Moon during an eclipse is round shaped. This is due to the Earth's spherical shape and the projection of its shadow onto the Moon's surface.

Earth is the third planet in the Solar System.

It comes after Mercury and Venus.

It is the only planet with life.

What is the Atmosphere?
The atmosphere is a layer of gases that surrounds the Earth. It is essential for life and plays a crucial role in various natural processes.
Composition of the Atmosphere
- The atmosphere is made up of about 78% nitrogen, 21% oxygen, and small amounts of other gases like carbon dioxide, argon, and water vapor.
- Oxygen is the most important component as it is vital for humans and animals to breathe.
Functions of the Atmosphere
- Provides Air to Breathe: The atmosphere contains oxygen, which is necessary for respiration in living organisms.
- Regulates Temperature: It helps to keep the Earth's temperature stable by trapping heat from the sun, preventing extreme temperature changes.
- Protects from Harmful Radiation: The atmosphere absorbs and reflects harmful solar radiation, safeguarding life on Earth.
- Weather and Climate: It is responsible for weather patterns and climate, influencing rainfall, temperature, and wind.
Conclusion
Thus, the atmosphere is fundamental for sustaining life on Earth by providing the air we breathe, regulating temperature, and protecting us from harmful elements. It is vital to understand and appreciate this protective layer that surrounds our planet.

Most of Earth’s surface is water.

Oceans, rivers, lakes cover two-thirds.

The rest is land with forests, mountains, deserts.

Earth moves around the Sun in a path.

This movement is called revolution.

It causes seasons on Earth.

Understanding the Water Cycle
The phenomenon driven by the Sun that involves the continuous movement of water on, above, and below the surface of the Earth is known as the water cycle.
Key Stages of the Water Cycle:
- Evaporation:
- Water from oceans, rivers, and lakes heats up due to the Sun's energy and transforms into water vapor, rising into the atmosphere.
- Condensation:
- As the water vapor rises, it cools and condenses to form clouds. This process is crucial for the formation of precipitation.
- Precipitation:
- When the clouds become heavy with water droplets, they release this water back to the Earth in the form of rain, snow, sleet, or hail.
- Collection:
- The precipitation collects in bodies of water like rivers, lakes, and oceans, where the cycle begins anew. Some water also seeps into the ground, replenishing groundwater supplies.
Importance of the Water Cycle:
- Supports Life:
- The water cycle is essential for all living organisms. It provides fresh water for drinking, agriculture, and sanitation.
- Climate Regulation:
- It plays a crucial role in regulating the Earth's climate by distributing heat and moisture around the planet.
- Ecosystem Balance:
- The cycle maintains the balance of ecosystems by ensuring that plants and animals have access to water.
In summary, the water cycle is a vital system driven by solar energy, ensuring the continuous movement and recycling of water, supporting life, and regulating climate.

Answer:
Star:
- A star is a celestial object that generates its own light and energy through nuclear fusion in its core.
- Stars are composed primarily of hydrogen and helium.
- They exist in different sizes, colors, and temperatures.
- Stars can be categorized into different types such as main sequence stars, giant stars, dwarf stars, and supergiant stars.
- The Sun is considered a star.
- It is located at the center of our solar system.
- The Sun is classified as a main sequence star of spectral type G2V.
- It is approximately 4.6 billion years old and will continue to shine for several billion more years.
- The Sun's energy sustains life on Earth through the process of photosynthesis and provides heat and light.
Moon:
- The Moon is Earth's natural satellite.
- It does not generate its own light but reflects the sunlight.
- The Moon orbits around the Earth and takes about 27.3 days to complete one revolution.
- It has phases, such as full moon, new moon, crescent moon, and gibbous moon, depending on its position relative to the Earth and the Sun.
- The Moon has a rocky surface and lacks an atmosphere.
- It influences tides on Earth due to its gravitational pull.
Earth:
- Earth is the third planet from the Sun in our solar system.
- It is a terrestrial planet with a solid surface and an atmosphere.
- Earth is the only known planet to support life.
- It has a diverse range of ecosystems and is home to millions of species.
- Earth has a magnetic field that protects it from harmful solar radiation.
- It takes approximately 365.25 days to complete one revolution around the Sun.
Comet:
- A comet is a small celestial object composed of ice, dust, and rock.
- Comets have a highly elliptical orbit around the Sun.
- When a comet approaches the Sun, the heat causes the ice to vaporize, forming a glowing coma and often a tail.
- Comets are often visible from Earth during their close approach to the Sun.
Conclusion:
- Among the given options, the Sun is the star.
- The Moon is a satellite, Earth is a planet, and a comet is a different type of celestial object.

When Earth spins on its axis, it is called rotation.

It takes 24 hours for one rotation.

It causes day and night.

Understanding Venus' Visibility
Venus, often referred to as the "Evening Star" or "Morning Star," is one of the brightest objects in the night sky. Its visibility throughout the year can be attributed to its position relative to the Earth and the Sun.
Why Venus is Visible at Dawn or Dusk
- Orbit and Position: Venus orbits the Sun at a distance closer than Earth. This means that it is often situated between the Earth and the Sun, making it visible during certain times of the day.
- Phases of Venus: Similar to the Moon, Venus goes through phases. During its cycle, it can be seen just before sunrise (dawn) or just after sunset (dusk), depending on its position in its orbit.
- Brightness: Venus reflects sunlight effectively, making it exceptionally bright, which contributes to its visibility at these times.
Comparison with Other Times
- Midnight: At midnight, Venus is usually on the opposite side of the Sun, making it difficult to observe.
- Noon: During midday, the Sun's brightness overshadows Venus, rendering it invisible to the naked eye.
- Throughout the Day: Although Venus can occasionally be seen during the day, it is not consistently visible due to the Sun's glare.
Conclusion
In summary, Venus can be observed most of the year primarily at dawn or dusk, making option 'C' the correct choice. Its unique position in the solar system allows it to shine brightly during these times, captivating skywatchers around the globe.

One full spin of Earth takes 24 hours.

This is equal to one day.

That’s why we have day and night in a day.

The Earth takes a year to revolve around the Sun.

As it moves, different parts get different sunlight.

This creates summer, winter, spring, and autumn.

Half of Earth faces the Sun—this side has day.

The other side is dark and has night.

This change happens as Earth spins.