Where are they? There's something called the Kuiper belt, which -- some people think Pluto's not a planet, that's where Pluto is, it's in the Kuiper belt.
它们是什么？它们被称作柯伊伯带， 是个——一些人认为冥王星不是星球， 柯伊伯带就是冥王星所在地。