Kuiper Belt

  • Roughly 10 billion icy objects outside the orbit of Neptune.



  • Although believed to exist since 1930's, only discovered in 1992 because objects are far away and thus faint.
    • Brightest KBOs are the same as a 100watt light bulb on the Moon.
    • Exception is Pluto because it is covered by bright frost and so reflects 90% of sunlight.
    • Objects like the Moon reflect only a few percent.
    • That is why scientists originally believed that Pluto was much bigger than it is.