Zeta Minor Zeta Minor was the planet farthest out in the known universe . It contained a link to a dimension of anti - matter . Characteristics . Zeta Minor had a jungle - like terrain and was home to the anti - matter creature . Professor Sorenson believed that the planet was alive and , as he told Baldwin , that it " [ watched ] every move they [ made ] . " The surface was divided into sectors for the purpose of designation . Salamar described its location as being " beyond Cygnus A " , " as distant again from the Ortoro Galaxy as that galaxy [ was ] from the Anterades . [ It was ] on the very edge of the known universe . " ( TV : " Planet of Evil " ) History . In the year 37166 , Professor Sorenson led an eight - man expedition to Zeta Minor in search of an alternate power source that would save the Morestran civilisation . When they found the first high quality strain , the expedition began to suffer from casualties — Lorenzo was the first — and the strain was found to have vanished . Sorenson believed the planet had " taken it back " . While in sector 5 , Sorenson and Baldwin came across a vein with over seventy percent purity . The professor was unwilling to leave , despite the approach of nightfall , lest the vein should vanish again . At the expedition base , Braun was killed by the anti - matter creature . Baldwin returned to the base alone and , finding himself under attack , pressed the automatic distress button before he too was killed . The Fourth Doctor and Sarah Jane Smith came to Zeta Minor in response to this signal , landing shortly before a Morestran probe ship began orbiting the planet . This ship was captained by Controller Salamar , who rejected Vishinsky ' s request for a low level scan of the planet in order to conserve fuel and ordered him to take a party down to the surface . Sarah soon found the planet to be having a strange effect upon and felt as if she " was being drawn from her body " . Finding the dessicated corpse of Braun , the product of the anti - matter creature , the Doctor thought they must have landed months too late . The Morestran party send the Doctor ' s TARDIS up to their ship before the ship itself landed on Zeta Minor . The Doctor and Sarah were both taken prisoner and charged with the recent murder s . They escaped and discovered anti - matter in a pool - like state on the planet ' s surface . O ' Hara became the next victim of the creature and Ponti fell into the " pool " . By helping the Morestrans fend off an attack on their probe by the creature , they gained their confidence . The presence of anti - matter mineral s on the probe prevented it from taking off as the creature desired their return . The Doctor took a small contained of these minerals before heading through the jungle to negotiate with the creature . He plunged into the " pool " where he promised that the anti - matter would be restored to this other dimension . The minerals he kept about his person allowed him to re - emerge . The majority of the minerals were removed from the ship , but Sorenson secreted some . The ship took off , but was unable to escape the planet ' s gravity due to this concealment . Under attack from Sorenson , whom the minerals had infected , several crew members were killed . The Doctor used his TARDIS to return to the planet ' s surface with Sorenson and the remaining minerals - both of which were submerged in the anti - matter " pool " . The promise fulfilled , the creature restored Sorenson to his former self and allowed the ship to leave . ( TV : " Planet of Evil " )