[MrB]

Comets lose mass every time they pass the sun.
If the solar system is “billions” of years old,
why are there still comets?

There’s been no observation of any “comet factory” on the edge of the solar system.

[VanShuyten]

There's no “comet factory,” but there is a “comet bank” called the Kuiper belt out beyond the gas giants.

[Cheburashka]

There’s been no observation of any “comet factory” on the edge of the solar system.

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http://nineplanets.org/kboc.html

[FroggyTheGremlim]

“There’s been no observation of any “comet factory” on the edge of the solar system.”

http://www.universetoday.com/32522/oort-cloud/