BPSC CCE Prelims
Earth and Universe Previous Year Questions (PYQs)

Detailed Explanation:

Comets have highly elongated elliptical orbits, originating from the Oort Cloud or Kuiper Belt, traveling close to the Sun at perihelion and far away at aphelion (e.g., Halley's Comet).

Asteroids have nearly circular orbits in the asteroid belt between Mars and Jupiter; meteorites are fragments that land on Earth with no orbit; meteors are light streaks from burning meteoroids with no permanent orbit.

Detailed Explanation:

Geodesy is the Earth science dealing with the measurement and representation of Earth's shape, size, and dimensions, including its gravitational field and orientation in space.

Option 1 refers to geochronology, Option 3 to topography/hypsometry, and Option 4 to tectonics/geology—none define geodesy's core function of measuring Earth's dimensions.

Therefore, geodesy's primary focus on Earth's measurement makes Option 2 the correct answer.

Detailed Explanation:

Saturn has the lowest density of all planets at approximately 0.687 g/cm³—less than water (1 g/cm³). Its composition is primarily hydrogen and helium gases with a small rocky core, making it extremely light relative to its volume.

Earth (5.52 g/cm³), Venus (5.24 g/cm³), and Mars (3.93 g/cm³) are terrestrial planets with dense metallic cores and rocky surfaces, resulting in significantly higher densities.

Therefore, Saturn has the least density, making Option 4 the correct answer.

Detailed Explanation:

The Sun is the central and most massive body of the solar system, containing over 99% of its total mass. All planets, asteroids, comets, and other celestial objects revolve around it due to its immense gravitational pull.

Jupiter and Saturn are the largest planets but remain much smaller than the Sun. Earth is our home planet but neither central nor dominant in mass.

Therefore, the Sun is the chief heavenly body, making Option 3 the correct answer.