Which of the following planets is nearest to the Sun?

The correct answer is Mercury.

Key Points

• Mercury is the closest planet to the Sun in our solar system, with an average distance of approximately 57.91 million kilometers (35.98 million miles).
• It takes Mercury only about 88 Earth days to complete one orbit around the Sun, making it the planet with the shortest year in the solar system.
• Despite being closest to the Sun, Mercury is not the hottest planet; that title belongs to Venus due to its thick atmosphere that traps heat.
• Mercury has a very thin atmosphere (exosphere) composed mostly of oxygen, sodium, hydrogen, helium, and potassium, which cannot retain heat effectively.
• Its small size (about 4,880 kilometers in diameter) and proximity to the Sun make it difficult to observe without advanced telescopes, except during rare transits.

Additional Information

• Order of Planets from the Sun:
  • The planets in order from the Sun are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
  • Pluto, once considered the ninth planet, is now classified as a "dwarf planet" by the International Astronomical Union (IAU).
• Rotation and Revolution of Mercury:
  • Mercury has a unique 3:2 spin-orbit resonance, meaning it rotates three times on its axis for every two orbits around the Sun.
  • A single day (one full rotation) on Mercury takes about 59 Earth days.
• Surface Features:
  • Mercury's surface is heavily cratered, similar to the Moon, due to its lack of a protective atmosphere to prevent meteorite impacts.
  • Notable features include the Caloris Basin, one of the largest impact craters in the solar system, and large cliffs called scarps formed due to the planet's shrinking core.
• Exploration Missions:
  • NASA's Mariner 10 was the first spacecraft to visit Mercury in 1974-75, capturing detailed images of its surface.
  • MESSENGER (2011–2015) was the first spacecraft to orbit Mercury, providing extensive data about its composition and magnetic field.
  • The European-Japanese mission BepiColombo, launched in 2018, is currently en route to study Mercury's surface and environment in greater detail.