# How much does planet Earth weigh?

Welcome to Ask Professor Labcoat where Children’s Museum of Atlanta answers YOUR science questions!

One curious kiddo asked how much does planet Earth weigh?

Kate (Professor Labcoat), our fun-loving, inquisitive and super smart Science Educator, gave this answer:

There is no scale big enough to weigh the Earth, and the planet is zooming through the vacuum of space where gravity changes depending on what’s nearby. This means that scientists must figure out the weight of the planet using math and the laws of gravity.

Objects with mass (like planets) have gravity. Gravity pulls objects toward one another. This is called gravitational attraction.

Let’s use Mars as our partner in this equation. Beware: this formula is not as simple it looks! F = G(M1*M2/R2)F = how hard the gravity of the objects (like Earth and Mars) are pulling on each other.

G = 6.67259 x 10-11 Nm2/kg2. This is a constant, meaning it does not change

M1 and M2 = the two objects that are attracting each other. In this example, M1 is Earth and M2 is Mars.

R = how far apart the objects are from each other

All you have to do is plug them into the equation and solve for M1 (Earth). You will find that the weight of planet Earth is…

13,170,000,000,000,000,000,000,000 (1.3 x 1025) pounds! That’s thirteen septillion!

Thanks for your question!