If Eilmer had seen Halley's Comet 76 years earlier in 989, he could have been born about 984, making him about five or six years old when he first saw the comet, and therefore old enough to remember it. However the periodicity of comets was probably unknown in Eilmer's time, and so his remark "It is long since I saw you" could have referred to a different, later comet. Since it is known that Eilmer was an "old man" in 1066, and that he had made the flight attempt "in his youth", the event is placed some time during the early 11th century, perhaps in its first decade.