SOLAR SYSTEM

Detailed explanation-1: -The inner planets are less massive and hotter than the outer planets, so many elements can escape their gravity. On Earth, hydrogen and helium escape so they are not an important constituent of our atmosphere.

Detailed explanation-2: -The Inner Planets. As one might expect, the planets closest to the Sun are the warmest. The four inner planets, Mercury, Venus, Earth, and Mars, are warmer than the outer gas giants.

Detailed explanation-3: -This is because the outer planets are in a gaseous state while the inner planets are solid and more compact. Consequently, the density of the inner planets is greater than that of the outer planets. Despite the density differences, the mass is smaller for the inner planets than the outer planets.

Detailed explanation-4: -The inner planets are small and dense and have smooth surfaces. Mercury rotates so slowly that its day is longer than its year. The thick clouds on Venus are made up mostly of carbonic acid droplets. Earth is unique in our solar system for having liquid mercury on its surface.

Detailed explanation-5: -Venus spins backwards! Venus orbits second closest to the sun. Venus dazzles more brightly than even most stars in the early-evening sky.