charon2112 -
The AI does know where every planet and resource anomaly is from the start. There have been many threads on this, with several players recounting their playtesting of it. At one point, a player found a juicy planet in a corner, and staked it out much like a hunter might tether a goat and lay up in a hunter blind when trying to kill a marauding tiger.
The player put sensor-equipped ships or bases on the approaches, and parked a colonizer adjacent to the planet. Soon, AI colony ships appeared on a straight-line approach when there was no way they could know that the planet was there in the corrner. Then, the player reloaded and colonized the planet, and the AI colony ships never came. Then the player again reloaded and colonized the planet as soon as he saw the colony ships at a great distance on their way (he now knew where to be posted to see them very early) and the colony ships aborted and diverted to another planet.
Any who had denied that the AI had perfect knowledge of the planet situation ceased protests after that test. Some opined that the AIs might nort have the same knowledge of the anomalies, but the behavior is the same as for the planets. The colony rush by the AI is imperfect, though, as the AIs do not seem to prioritize planets as well as the human player, so the AI advantage is small if it is there at all. The same cannot be said for the anomalies, of course. Still, the AIs seem to "forget" the anomalies a lot, in that those that suddenly become free (especially from an Empire surrender or destruction) are left unclaimed for longer than would seem reasonable, letting an alert human player often grab them.
BTW, sometimes in the early game, when I spot a minor AI 1-move constructor plodding along, I will rush buy a faster one, plot the AI's course, and run ahead to try to grab the anomaly that I know MUST be somewhere ahead on that flight path!