automated machines to oversee and carry out their projects over the eons. When they encountered a living world that had features in favour of the evolution of intelligent life, they left behind the Monoliths as remote observers that were also capable of taking a variety of actions according to the wishes of their creators. One such planet, encountered when it was still quite young, was Earth. They also observed Jupiter and its watery moon, Europa. The decaying ecology of Mars was also visited, but passed over in favour of more fruitful locations like Earth. The Firstborn left behind three Monoliths to observe and enact their plan to encourage hominids to pursue technology and space travel. As described in Clarke's novel, the Firstborn discovered later how to transfer their consciousness onto computers, and thus they became thinking machines. In the end, they surpassed even this achievement, and were able to transfer entirely from physical to noncorporeal forms — the "Lords of the Galaxy" — immortal and capable of travelling at great speeds. The Firstborn had abandoned physical form, but their creations, the Monoliths, remained, and these continued to carry out their original assignments. Tycho Magnetic Anomalies The term "Tycho Magnetic Anomaly" is something of a misnomer when referring to "TMA-0" and "TMA-2", since neither of these is found on the Moon (let alone in Tycho Crater) and neither one of them emits any significant magnetic field, as described in the novel 2010: Odyssey Two. (The characters in some of the novels do refer to this anomalous nomenclature quizzically.) In the novel, the Russian crewmen of the spaceship Alexei Leonov refer to TMA-2 as "Zagadka" (from the Russian word for "enigma", "mystery", or "riddle"). Tycho Magnetic Anomaly-1 The name Tycho Magnetic Anomaly-1 (also known as TMA-1) refers to the strong magnetic field found somewhere in the lunar Crater Tycho by an American scientific satellite. Astronauts find that this magnetic anomaly is caused by an alien Monolith buried about 15 meters below the surface. In the novel, when the Monolith is excavated and examined, it is found to be a black cuboid whose sides extend in the precise ratio of 1 : 4 : 9 (12 : 22 : 32). Its measurements are given in the novel as ; actually a ratio of 1:4:8.8. The monolith is sitting on a platform of the same material above undisturbed rock. Clarke suggests that the sequence