Buzz
What is the Moon's weight?C Stuart Hardwick:
Absolutely nothing.
Alright, I may be overthinking it. The moon's mass, which you might have intended to ask about, is approximately 7.3476× 10^22 kilograms.
However, the moon doesn’t weigh anything.
Weight is closely linked to mass, but they aren’t exactly the same thing (even though we use the same terms for both). Weight is the force that gravity exerts on an object that is positioned against a larger mass. The moon is in freefall—it's orbiting—so it doesn’t experience weight. If it were on Earth’s surface, it would weigh around 7.3476 × 10^22 kilograms—but that would only last for a moment. After that, it would collapse under its own weight and become a catastrophic blemish on the Earth until it broke through the crust.
That would certainly be a disastrous day.
Thankfully, such an event is practically impossible. The moon is in orbit, which means it’s constantly falling toward Earth (which is why it doesn’t “feel” our gravity—it’s weightless), but it’s also drifting away into space. For each meter it falls toward us, it moves enough for Earth’s surface to curve away by one meter. Thus, like any orbiting body, it keeps going in circles endlessly.
This whole weight vs. mass confusion happens because, in everyday English, we use pounds and kilograms for both weight and mass. This is because we figured out all these concepts on Earth, where it’s easy and practical to measure mass by measuring weight.
In other words, as Earth inhabitants, we equate mass units with the units of weight observed on Earth.
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