Question 1: Define a planet and list the three criteria a celestial body must meet to be classified as a planet in our Solar System.

Answer: A planet is a celestial body that orbits the Sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and has cleared its orbital neighborhood of smaller objects.

Question 2: Explain why Mercury has a much higher surface temperature during the day compared to its night.

Answer: Mercury has a very thin atmosphere, so it cannot retain heat. During the day, sunlight heats its surface quickly, but at night, it loses heat rapidly, causing large temperature fluctuations.

Question 3: Calculate the orbital speed of Earth around the Sun. Use the formula: Speed = 2πr / T, where r = 149.6 million km and T = 365.25 days (convert T to seconds).

Answer: Approximate Earth's orbital speed is 29.78 km/s.

Question 4: Which planet is known as the 'Red Planet' and why?

Answer: Mars is called the 'Red Planet' because of its reddish appearance caused by iron oxide (rust) on its surface.

Question 5: Multiple Choice: Which planet has the shortest orbital period?

Answer: Mercury

Question 6: Fill in the blank: The planet with the largest number of moons in our Solar System is __________.

Answer: Jupiter

Question 7: Describe the main differences between terrestrial planets and gas giants in terms of composition and size.

Answer: Terrestrial planets, such as Mercury, Venus, Earth, and Mars, are composed mainly of rock and metal, have solid surfaces, and are smaller in size. Gas giants, like Jupiter and Saturn, are mainly composed of hydrogen and helium, lack solid surfaces, and are significantly larger and more massive.

Question 8: Explain the significance of the asteroid belt between Mars and Jupiter in planetary formation.

Answer: The asteroid belt represents remnants of planetesimals that never coalesced into a planet, providing clues about the early solar system and planetary formation processes.

Question 9: Identify one practical application of understanding planetary motions in modern technology or industry.

Answer: Understanding planetary motions is essential for satellite deployment, navigation systems like GPS, and predicting space weather that affects communication and weather forecasting.

Question 10: What safety precautions should be considered when designing spacecraft to explore planets?

Answer: Designing spacecraft requires considerations for radiation shielding, thermal protection against extreme temperatures, structural integrity to withstand launch and landing forces, and ensuring reliable communication systems for safety.