How Big Are Asteroids?

In the asteroid belt around the sun there are over 1 million asteroids 1km or bigger in diameter. That would seem to imply a lot of collective mass in all of these asteroids, right? So how do they compare to more familiar celestial bodies in our solar system? This science blog explains:

“While the combined mass of every asteroid is just 4% the mass of our Moon, Ceres and Vesta alone are estimated to make up nearly 40% of the mass of the entire belt.”

Just 4% of our moon in total? This means each asteroid is miniscule, relatively speaking. This makes you wonder too, if we ever start mining in space, why mess around chasing down distant asteroids? Just go to the moon for nearby one-stop shopping. (See pros and cons of mining the moon vs. asteroids here.)

The video below shows awesome close ups of Vesta.

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6 Comments on "How Big Are Asteroids?"

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What effect on the earth would harvesting the moon have? (Like tidal forces/ gravitational pull etc. could we create enough of a magnetic attraction to make asteroids hit the moon and what effect if possible would this have on the moon? (hasn’t it always been bombarded by them?) wouldn’t Saturn and Titan be easier and better to mine? Water on Titan, gases from Saturn and an almighty asteroid belt


Harvesting the moon’s effects depend on how much mass your taking off the moon. Although hard to say how much mass you’d need to remove before the effect is noticeable, there needs to be a huge mining operation or a steady one over a very long time (at least hundreds if not thousands or even millions of years).


Right now, with our limited technical/financial ressources , I think the moon is ideal.Of course, for medium/long term other places should be added to our ‘playground’.


I dislike the idéa of turning the moon into a quarry :s

Lord Penguin
They both are useful in their own ways, and I’d be surprised to see only one or the other being used. At the moment, we don’t have enough information about either to make a decision one way or the other. We’ve never landed on an asteroid, much less sent samples back. And although we’ve sent dozens of missions to the moon, we know very little about the subsurface. Mascons (mass concentrations), formed by giant asteroid impacts that melted surrounding rock into lava, might be troublesome for moon satellites, but could concentrate precious metals and spacecraft materials near the bottom, if… Read more »

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