Bobby Piiley, age 12 of Peterborough, Ontario, for his question:

How big is the planet Venus ?

Venus is called the earths sister planet because it is most like our world in size. One way to measure a sphere is by its diameter, a straight line Through the middle from side to side. Earth's diameter is about 7927 miles. The diameter of Venus is about 7,700 miles. This means that the earth is just a little larger than its sister.

Volume is the amount of space occupied by an object. So, because of its smaller size, the volume of Venus is slightly less than earth’s volume. Its volume is 0.92 of the volume of the earth.

The density of an object gives it mass or weight. The earths density is 5.52 times the density of water. The density of Venus is only 4.8 the density of water. The weight or mass of Venus, then, is considerably less than the mass of the earth. Because it is lighter and smaller the gravity of Venus also is less than the earth. If you weigh 100 pounds on earth you would weigh only 85 pounds on Venus.