How do I Compare the Size of Neptune to Earth?

Surface Area

• 1

  Find out the surface area of the Earth. The surface area of the Earth, according to NASA, is 510,065,700 square kilometers. This is the measurement of the entire mileage on the surface of the Earth and one way to compare the size of planets.

• 2

  Find out the surface area of Neptune. According to NASA, the surface area of Neptune is 7,640,800,000 square kilometers.

• 3

  Divide the surface area of Neptune (7,640,800,000) by the surface area of the Earth (510,065,700) to find the difference in size. The difference is 14.98, meaning the surface area on Neptune is almost 15 times as large as on Earth.

Mass

• 4

  Find out the mass of the Earth. The mass of Earth, according to NASA, is 5,973,700,000,000,000,000,000,000 kilograms.

• 5

  Find out the mass of Neptune. According to NASA, the mass of Neptune is 102,440,000,000,000,000,000,000,000 kilograms.

• 6

  Divide the mass of Neptune (102,440,000,000,000,000,000,000,000) by the mass of the Earth (5,973,700,000,000,000,000,000,000) to find the difference in mass. The difference is 17.14, meaning the mass of Neptune is a little over 17 times as large as Earth's.

Diameter

• 7

  Find out the diameter of the Earth. The diameter of Earth, according to NASA, is 12,756.29 kilometers. This is the distance around the Earth along its central point, called the equator.

• 8

  Find out the diameter of Neptune. According to NASA, the diameter of Neptune is 49,528 kilometers.

• 9

  Divide the diameter of Neptune (49,528 kilometers) by the diameter of the Earth (12,756.29 kilometers) to find the difference in diameter. The difference is 3.88, meaning the diameter of Neptune at its equator is almost four times as large as Earth's.