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Does NASA Know About All the Asteroids?

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We Asked a NASA Scientist.

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Well, no. But the good news is we know\h
where most of the really big ones\hare

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that get closest to the Earth. We've\h
found more than 90 percent of these.

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That's the great news. But there are a lot more\h
smaller pieces that are still out there that we

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haven't found. It's really challenging to\h
find asteroids and comets simply because

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even though some of them are as big as mountains,\h
space is incredibly huge and these things can be

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really far away. In fact, we want to find them when\h
they're very far away from the Earth so we have

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lots of time to take action if we ever find\h
one that's really headed in our direction.

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Asteroids are both a source of fascination but\h
sometimes fear because we wonder, can they hit the Earth?

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It's really incredibly unlikely that\h
a significant asteroid impact is going to occur

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in our lifetimes. However, that said, if even one\h
happens it could be really bad. And that's why

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we want to go out and look for these objects\h
and make sure that the Earth and an asteroid

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never get too close for comfort. So does NASA\h
know about all the asteroids? Well no, but we know

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what we have to do and we're on the job and we're\h
really glad to be part of team planetary defense.