# Are comets known to exist in other star systems?

Are comets a feature unique to our Solar System? Or, are comets/cometary clouds detected around discovered/observed extra-solar systems too? If they were detected elsewhere, how do such cometary clouds affect discovery by perturbation of planets in that system ?

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Scale, again. The lightest exoplanet yet discovered is just over 1 Earth mass and close in. How big is your typical comet? –  dmckee Oct 17 '12 at 19:55
A fraction of Earth's mass. In other words, then, given the state of technology the question cannot be answered one-way-or-the-other ? –  Everyone Oct 17 '12 at 20:20
Well, you asked "Are they known to exist?", which is answerable in the negative, but there was no reason to expect that it might be answerable in the positive. –  dmckee Oct 17 '12 at 20:42

Their individual masses are relatively very small compared to discovered planets. For example, Halley's Comet has a mass of roughly $2.2\times10^{14} kg$ compared to roughly $6\times10^{24} kg$ for the Earth. That's a factor of 30 billion times smaller... so it is also unlikely that the same techniques used to discover Earth-sized or larger planets would find comets, too.