Isso é discutido (extensamente) no livro de acompanhamento . Em suma, o segundo monólito era um dispositivo de alarme destinado a mostrar que os macacos do planeta tinham evoluído ao ponto de serem capazes de alcançar seu vizinho planetário mais próximo e realizar tarefas básicas de levantamento. Sendo esse o caso, agora seria benéfico para os monólitos-construtores para ativar a fase II de seus planos, criando um segundo sol no sistema solar para permitir a colonização das luas de Júpiter.
"Piecing things together after the event, we decided that the monolith was some kind of Sun-powered, or at least Sun-triggered, signaling device. The fact that it emitted its pulse immediately after sunrise, when it was exposed to daylight for the first time in three million years, could hardly be a coincidence.
"Yet the thing had been deliberately buried - there's no doubt about that. An excavation thirty feet deep had been made, the block had been placed at the bottom of it, and the hole carefully filled.
"You may wonder how we discovered it in the first place. Well, the object was easy - suspiciously easy - to find. It had a powerful magnetic field, so that it stood out like a sore thumb as soon as we started to conduct low-level orbital surveys.
"But why bury a Sun-powered device thirty feet underground? We've examined dozens of theories, though we realize that it may be completely impossible to understand the motives of creatures three million years in advance of us.
"The favorite theory is the simplest, and the most logical. It is also the most disturbing."You hide a Sun-powered device in darkness - only if you want to know when it is brought out into the light. In other words, the monolith may be some kind of alarm. And we have triggered it.