Astronomers find unexpected comets in outer reaches of solar system

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Using data from the WISE space telescope, astronomers have found that there are more comets lurking in the far reaches of the solar system than they had predicted.

Scientists found that there are about seven times more long-period comets measuring at least 0.6 miles (1 kilometer) across than had been predicted previously. They also found that long-period comets are on average up to twice as large as “Jupiter family comets,” whose orbits are shaped by Jupiter’s gravity and have periods of less than 20 years. Researchers also observed that in eight months, three to five times as many long-period comets passed by the Sun than had been predicted.

These are comets whose orbits never allow them to come close to the inner solar system, which allows them to remain puffy and large.



  • pzatchok

    Puffy and large means just full of water. Something easy to harvest way out there.

  • J Fincannon

    “These are comets whose orbits never allow them to come close to the inner solar system, which allows them to remain puffy and large.”

    A list of these long period (>200 year orbit but <1000 year) comets is here.
    One can define "come close to the inner solar system" as less than the distance of the asteroid belt (~3 AU). I count ~100 of these comets with a perihelion of <3 AU out of the list of 116. 36 of the comets on this list pass less than 1 AU from the Sun.

    Thus, I do not think your statement is correct.

    The time frame of a mere 200 years seems infinitesimally short in the long time of the solar system (5 billion years), so they should have passed millions of times through the inner solar system over that period.

    Also look at this list.
    One of those has an orbit period estimated to be 130,000,000 years! That one would have passes as close as 4.2 AU ~38 times over the solar system age.

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