Final answer:
The planet Kepler 62-c has no equivalent in size in our solar system, as it is categorized as a super-Earth, with a diameter larger than Earth yet smaller than Uranus or Neptune. However, the closest planet in size would be Earth itself.
Step-by-step explanation:
The student wants to identify the name of the planet in our solar system that has an equatorial diameter most similar in size to that of the planet Kepler 62-c. From the Kepler Discoveries indicates that super-Earths have radii between 1.4 and 2.8 times that of Earth. When comparing to our solar system's planets, we find that none exactly match this size range; however, Kepler 62-c falls into the category of super-Earths, making it larger than Earth but smaller than the gas giants like Neptune and Uranus.
Given the information from the study model that the Earth is like a grain of sand and Jupiter, Saturn, Uranus, and Neptune are much larger, like grapefruits, oranges, and lemons, we can deduce that the planet in our solar system with a diameter closest to that of Kepler 62-c would be Earth, since it is the only rocky planet in our solar system with a diameter somewhat close to the size range of a super-Earth.