If the sun were the size of an NBA basketball, how big would the Earth be?

• A. A raisin
• B. A grain of salt
• C. A marble
• D. A peppercorn

Answer: (A)

Think about how big the Sun is compared to the Earth and shrink everything down so the Sun fits into the size of an NBA basketball. The Sun’s diameter is about 109 times larger than Earth’s. If the Sun becomes a basketball about 24 centimeters across, Earth would be only about 24 cm divided by 109, which is roughly 0.22 cm, or about 2 millimeters, across.

That puts Earth at a tiny, bead-like size. Among common small objects, a raisin is a compact, roughly millimeter-to-a-few-millimeters-scale object that people can picture easily, and it is the option that best conveys “very tiny” in this set. The other items listed are noticeably larger or smaller than a 2-millimeter dot, so the raisin is the closest intuitive match for Earth on this scale.