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HardShelledTurt t1_itndv2v wrote

Reply to comment by BartyDeCanter in Deflecting asteroids is not enough — we need to know when they approach by burtzev

How can you be sure they're all catalogued? You don't know what you don't know

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BartyDeCanter t1_itney45 wrote

That is, of course, an excellent point. What we do have is estimates from a few different methods (mass distribution, perturbation analysis, discovery curve, etc) and they are converging on <1000 NEOs larger than 1km. Here's a nice, though slightly outdated, graphic: https://www.nasa.gov/mission_pages/WISE/multimedia/gallery/neowise/pia14734.html

And a recent paper giving an estimate of 940+-10. https://www.sciencedirect.com/science/article/abs/pii/S0019103521001342

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Edit: Article link

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Xbxbxb123 t1_itnkmx3 wrote

The simple answer is that you can estimate how many there are total by how many you've found and how hard you had to look.

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