Icarus IV
Icarus IV was a comet which passed close to the Romulan Neutral Zone in 2266. This comet, with a magnitude of seven, was an ionized mass that left a trail of frozen vapor particles. Information on this comet was recorded in the Table of Comets.

In that year, the commander of an experimental Romulan Bird-of-Prey ordered his cloaked ship into the tail of the comet, in an attempt to elude the Federation Starship , which had been pursuing them. Unfortunately for the Romulans, James Kirk, the Enterprises commanding officer, anticipated this move, and used the Bird-of-Prey's disturbance of the comet's tail to calculate the Romulan vessel's position, and mount an attack. ()

In an alternate timeline, created by Christopher Pike avoiding his injury in 2266, the  under the command of Pike and the  under the command of James T. Kirk would attempt a similar method to expose the Bird-of-Prey but utilizing a pincer maneuver. However, upon clearing the comet, the Bird-of-Prey was not detected, instead appearing behind the Farragut, destroying it. ()

See also 
 Icarus IV Spaceport

External link 
 

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Comets
Romulan Neutral Zone