One of Our Planets Is Missing ( episode ) The " Enterprise " crew learns that a massive , planet - destroying cloud has entered Federation space . Summary . As the " Enterprise " nears the Pallas 14 system , the cloud engulfs planet Alondra , and the planet completely disappears from sensors . Lieutenant Uhura believes that the cloud may have blocked it from being scanned , but Spock reports that the cosmic cloud engulfed it , and broke it up into small pieces in seconds . Captain Kirk asks , " " Spock , is it possible that the cloud consumes planets ? " " Spock answers in the affirmative . Suddenly and without warning , the cloud changes course , heading directly for Mantilles . Kirk orders Sulu have the speed increased to warp 8 in order to intercept the cloud more quickly . The " Enterprise " maneuvers itself directly into the path of the cloud and the ship is engulfed . It is pulled into the cloud by streamers made of koinoenergy , an almost ambiplasma with an unusually attractive force . When Kirk gives the order to fire phaser s , Spock reports that the cloud seems to be absorbing the phaser energy . Since it is unknown if the entity has selective abilities , the " Enterprise " crew assumes that not only Mantilles , but all planets and star systems are in danger . The " Enterprise " decides to warn Bob Wesley , governor of Mantilles . But before it can do so , the ship is engulfed by the cloud , and unknown objects comprised of highly charged , gaseous antimatter swarm the vessel , causing a large power drain of the shields . An antimatter charge from the shield is successful in dissipating the objects . Research by Spock indicates that the cloud is actually a living being , and that the objects act like enzyme s , slowly breaking up the remnants of Alondra and the " Enterprise " . After more studying of the creature ' s anatomy , the " Enterprise " plots a course through the digestive system , with enormous power consumption . To regenerate the ship ' s rapidly declining antimatter reserves , Montgomery Scott cuts off a piece of the creature ' s villi , has Kyle beam it aboard , and uses it to create power regeneration of the ship ' s anti - matter reserves , with minutes to spare . Kirk sighs , " " Scotty , you ' ve just given the " Enterprise " , and Mantilles , a chance to live . " " Scott replies , " " Thank you , sir . " " Spock then ascertains the being has a brain and , on hearing this , Kirk plans to use the " Enterprise " s complement of photon torpedo es to destroy the cloud ' s brain . When Spock begins to remind Kirk of the Starfleet regulations against the killing of intelligent creatures , Kirk stops him , noting that he is well aware of the regulations . But they don ' t yet know if the cloud is intelligent and it is a fact that every living thing on Mantilles will die , unless they stop the cloud , and so if Kirk is forced to make a choice , he chooses saving Mantilles . Feeling very unsure about his decision , Kirk asks , " " Am I doing the right thing , Bones ? Once I said that man rose above primitiveness by vowing , ' I will not kill , today . " " The ever - pragmatic Bones replies , " " But you can ' t let this thing destroy eighty million lives , either . " " Spock tells them the brain is so vast that the " Enterprise " s entire complement of armaments may not guarantee its destruction . He determines that they would have to destroy the " Enterprise " itself and direct the explosion right at the cerebral cortex . Kirk orders Scott to prepare the ship for self - destruct and Spock to try to establish contact with the creature . Spock uses a Vulcan mind meld to contact the creature and allows the creature to see glimpses of Human life for the first time . The creature comes to understand that its food , the planets , are inhabited by " " many somethings , so small , but alive . Comprehend . Not desire to consume other beings . " " The creature allows the " Enterprise " to leave peacefully and agrees to depart the galaxy . Kirk asks , " " Spock , what did you perceive ? " " The first officer replies , " " The wonders of the universe , captain . Incredible , completely incredible . " " Memorable quotes . " " It ' s immense ! Twice the diameters of Saturn , Jupiter and Neptune together ! " " " " Spock , is it possible the cloud consumes planets ? " " " " It is possible this cloud in which we are entrapped is a living thing . The cloud " is " alive . " " " " Scotty , you ' ve just given the " Enterprise " , and Mantilles , a chance to live . " " " " Thank you , sir . " " " " Am I doing the right thing , Bones ? Once I said that man rose above primitiveness by vowing , ' I will not kill , today . " " " " Spock , what did you perceive ? " " " " The wonders of the universe , captain . Incredible . Completely incredible . " " Links and references . References . 2258 ; Alondra ; ambiplasma ; amoeba ; anatomy ; anti - kilo ; antimatter ; antimatter charge ; antimatter engine ; Bezride ; " Bones " ; bull ; chemical identity sensors ; collie ; corrosion ; deflector screen ; digestive system ; Earth ; element ; energy ; engineering core ; evasive action ; Federation ; Five thousand children ; force field box ; Gabler ; Governor ; indigestion ; judge ; Jupiter ; kilometer ; koinoenergy ; library computer ; logic ; macromorphase enzyme ; Mantilles ; matter ; matter engine ; Milky Way Galaxy ; nacelle ; Neptune ; offensive armament ; Pallas 14 system ; periodic table ; priority one call ; psychology ; remote control ; Saturn ; self - destruct mechanism ; small intestine ; stomach ; Starfleet ; Starfleet Command ; Starfleet General Orders and Regulations ; stomach ; teeth ; tractor beam ; transporter ; universal translator ; villi ; Vulcan mind touch ; Wesley , Katie