All questions of Beyond Earth for Class 6 Exam

Option B, Revolution

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

Primary Source of Heat and Light
The Sun is the central and most significant body in our Solar System, providing essential heat and light necessary for life on Earth. Here’s a detailed explanation:
1. The Sun's Composition
- The Sun is primarily composed of hydrogen and helium.
- It generates energy through nuclear fusion, a process where hydrogen atoms combine to form helium, releasing vast amounts of energy.
2. Energy Emission
- This energy is emitted in the form of light and heat.
- The Sun’s surface temperature is about 5,500 degrees Celsius (9,932 degrees Fahrenheit), which contributes to the intense heat and brightness.
3. Importance of the Sun
- The Sun is crucial for photosynthesis, the process by which plants convert sunlight into energy.
- It regulates Earth's climate and weather patterns, influencing ecosystems and habitats.
4. Distance and Influence
- The Sun is approximately 93 million miles (150 million kilometers) away from Earth.
- Its gravitational pull keeps the planets, including Earth, in orbit, maintaining the structure of the Solar System.
5. Comparison with Other Celestial Bodies
- The Moon reflects sunlight and does not produce its own light or heat.
- Earth generates internal heat through radioactive decay and geothermal processes but relies on the Sun for external heat and light.
- Jupiter, despite being a massive planet, does not emit significant heat or light; it reflects sunlight like the Moon.
In summary, the Sun is the primary source of heat and light in our Solar System, playing a vital role in sustaining life and maintaining the balance of nature on Earth.

Identifying Orion
Orion is one of the most recognizable constellations in the night sky, particularly famous for its distinctive pattern.
Orion's Belt
- Orion’s Belt consists of three bright stars: Alnitak, Alnilam, and Mintaka.
- These stars are aligned in a straight line, making them easily identifiable.
Location and Visibility
- Orion is best visible during winter in the Northern Hemisphere and summer in the Southern Hemisphere.
- The constellation is located on the celestial equator, making it visible worldwide.
Other Features of Orion
- Orion is often depicted as a hunter in mythology, holding a bow and arrow.
- In addition to Orion's Belt, the constellation also contains other notable stars and features, such as Betelgeuse (a red supergiant) and Rigel (a blue supergiant).
Why Not Other Options?
- Ursa Major: Known for the Big Dipper, not aligned like Orion's Belt.
- Ursa Minor: Home to Polaris, the North Star, but lacks a prominent belt structure.
- Cassiopeia: Recognized for its W shape, not a series of bright stars in a row.
Conclusion
In summary, Orion is the correct answer because it is defined by the easily recognizable three stars in a row known as Orion's Belt, distinguishing it from other constellations.

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.

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.

Comets are composed of dust, ice, and gases, and form a glowing coma and tail when they approach the Sun.

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

Although the Sun is just one star among many, it appears larger because it is much closer to Earth compared to other stars.

Nubra, Ladakh has minimal light pollution, which allows more stars to be visible in the night sky.

The Astronomical Unit (au) is the standard unit used to express distances within our Solar System, roughly equal to the distance between the Earth and the Sun.

Ancient sailors used the stars as navigational aids to determine their direction and guide their voyages.

Asteroids are small, rocky objects that orbit the Sun, mostly found in the asteroid belt between Mars and Jupiter.

The Milky Way is the galaxy that contains our Solar System, composed of billions of stars and other celestial objects.

Comets consist of dust, gas, rocks, and ice. When they approach the Sun, the heat causes the ice to evaporate, creating a glowing coma and tail.

Our Solar System is located in the Milky Way Galaxy.

A constellation is a group of stars that form a recognizable pattern, often based on mythology or stories.

The IAU has defined 88 constellations to organize the night sky into distinct regions.

Polaris, the Pole Star, remains almost stationary in the sky, making it a reliable indicator of the North direction.

The inner planets (Mercury, Venus, Earth, and Mars) are rocky with solid surfaces, while the outer planets are primarily gaseous.

Natural satellites, such as the Moon, are objects that orbit a planet.

Mars is known as the Red Planet due to its reddish appearance caused by iron oxide (rust) on its surface.

Stellarium is a popular app that helps users identify stars, constellations, and planets using their mobile devices.