Predicted by old records, by applying the known repeating pattern of cycles. Bingo !

The Lord God's calendar and time keeping system, He gave us.                                                                                                                                                                                                                                                                                   14 And God said, Let there be lights in the firmament of heaven to divide the day from the night; and let them be for signs, and for seasons, and for days and years: 15 and let them be for lights in the firmament of heaven to give light upon the earth: and it was so.        16 And God made the two great lights; the greater light to rule the day, and the lesser light to rule the night: [he made] the stars also.        17 And God set them in the firmament of heaven to give light upon the earth, 18 and to rule over the day and over the night, and to divide the light from the darkness: and God saw that it was good.