Question

The planet with the shortest year is………….
a.Earth
b.Mercury
c.Mars
d.Pluto

Answer 1

Hint: The planet closest to the sun has the shortest orbital period. This means it takes less time to complete one orbit around the sun. Shorter the orbital period, lesser is the time taken to orbit around the sun.

Complete answer: The definition of a year is the time taken by a planet to complete a single Orbit around the sun.The Earth takes 365 days and 6 hours to complete one orbit around the sun and thus is considered one year for Earth.
For Mercury, the orbital period is 88 days (87.969 to be exact). That means Mercury takes 88 Earth days to complete one orbit around the sun. That is, a year for Mercury is 88 Earth days and therefore, the shortest of all the planets. The reason behind is Mercury being the closest planet to the Sun. It covers a distance of 57,909,050 km which is slightly more than one-third of the distance between Sun and Earth. The orbital path that is the distance Mercury orbits around the sun is short. Being close to the Sun, the gravitational pull of the sun is greater on Mercury. The stronger the gravitational pull, the faster the planet orbits.

Looking at the options given:
Option a: Earth takes 365 days and 6 hours to complete one orbit around the sun. It is an incorrect answer.
Option b: Mercury takes 88 Earth days to complete one orbit around the sun and hence shortest of all other planets. It is the correct answer.
Option c: Mars takes 687 Earth days to complete one orbit around the sun. It is an incorrect answer.
Option d: Pluto takes 248 Earth years to complete one orbit around the sun. It is an incorrect answer.

Hence, Option ‘b’ is correct.

Note: A year is the time taken to complete one orbit around the sun. That is, it depends on the length of the orbital period. Since Mercury has the shortest orbital period, it takes least time to complete one orbit around the Sun.