The planet most similar in size to Earth is Venus.
The planet most similar in size to Earth is Venus. To find this answer, one can compare the sizes of the planets. Earth has a diameter of about 12,742 kilometers. Venus has a diameter of about 12,104 kilometers, which is the closest in size to Earth among the given options. Neptune is much larger in size, with a diameter of about 49,244 kilometers. Both Jupiter and Mars are also significantly larger or smaller in size than Earth.
