Question

The farthest planet from the earth is
(A) Pluto
(B) Mercury
(C) Neptune
(D) Saturn

Answer 1

Hint We are asked to come to a conclusion on which of the given options, the farthest planet from earth is. Thus, we will take into consideration the real direct distances of the heavenly bodies. Also, we will consider the concept of cosmic measurement.

Step By Step Solution
Here, we are given four planets. Out of these, only one planet lies under the asteroid belt of our solar system. Also, Pluto cannot be considered as a planet as it does not spiral around a certain orbit. In other words it interferes in the motion of the other planets in their respective fixed orbits thus hampering the criteria for being a planet. However, it can be considered as a dwarf planet.
Now, According to the studies of NASA and other astronomical institutions all around the globe has said that it is not possible to measure accurate distances of the planet from the sun beyond the asteroid belt by real direct distances. Precisely speaking, it is out of the scope of real direct distances to measure distances beyond a thousand parsecs.
Therefore, they came up with a solution for the cosmic distance ladder. This ladder is also known as extragalactic distance scale. This is the succession of methods by which astronomers try and determine the distances to celestial and heavenly objects. Instead, one of the methods can also be used for measuring nearby distances.
Thus, from the available experimental data on the cosmic ladder, Saturn is the farthest planet from the earth.

Hence, the answer is (D).

Note Students might be confused that Neptune lies towards the end of the solar planet sequence and thus lying beyond Saturn. So they might be mistaken of considering Neptune as the farthest planet from the earth. But they must remember that the conclusion of which planet is the farthest is depending totally on the place of the planet in the cosmic distance ladder. This ladder cannot be analogous to the real direct distance concepts.