four o'clock
He learned the rocket was going to the moon by listening to Dad and the other scientists talk when they thought they were alone . And it was funny . Because even there , they spoke in low voices and did n't give too much away . He had known now for three days that at four o'clock the roof would open and the drome would be turned into a blast-pit and the rocket would shoot out through space to the moon . That was all he _ did _ know for sure . None of the men had said who was going on the first trip to the moon . Nothing had been said on that subject at all , but Bobby knew Dad would go .