====== 'Lost' comets ======

It's usually possible to compute (with good accuracy) the paths of Solar System comets from observational data. Sometimes, however, they don't behave as expected, and are classified as 'lost'.

There are a number of reasons why a comet might not adhere to its previously calculated path :

  * The comet may have disintegrated or evaporated en route
  * Its orbit may have changed due to a close encounter with another object
  * Its orbit may have 'ejected' it from the Solar System
  * The orbital period is too long to calculate (i.e. one recorded 'visit' only)

Wikipedia maintains .[[https://en.wikipedia.org/wiki/Lost_comet#List|a list of known 'lost' comets]] (currently over 30 of them).

Note that because some comets have very long orbital periods, they are occasionally thought-of as 'lost' but then reappear -  as happened with [[https://en.wikipedia.org/wiki/177P/Barnard|177P/Barnard]]