When in your bookcase, this text is called The Tale of Scorpius.
Below is the text you can read from within the book.
THE TALE OF SCORPIUS
A History of Astronomy in RuneScape.
At the start of the 4th age, a learned man by the name of Scorpius, known well for his powers of vision and magic, sought communion with the gods of the world. So many unanswered questions had he that devoted his entire life to this cause.
After many years of study, seeking knowledge from the wise of that time, he developed a machine infused with magical power, infused with the ability to pierce into the heavens - a huge eye that gave the user incredible sight, like never seen before.
As time passed, Scorpius grew adept at using his specialized skills, and followed the movements of the stars in RuneScape, which he mapped and named, and are still used to this very day.
Before long, Scorpius used his knowledge for predicting the future, and, in turn, he called upon the dark knowledge of Zamorakian worshippers to further his cause. Living below ground, the followers of the dark god remained until the civilization of Ardougne grew in strength and control.
The kings of that time worked to banish the Zamorakian followers in the area, hiding all reference to Scorpius's invention, due to its 'evil nature'.
Years later, when the minds of the kings lent more towards the research of the unknown, the plans of Scorpius were uncovered and the heavenly eye constructed again.
Since then, many have studied the ways of the astronomer, Scorpius and in his memory a grave was constructed near the Observatory.
Some claim his ghost still wanders nearby, in torment as he seeks the secrets of the heavens that can never be solved. Tales tell that he will grant those adept in the arts of the astronomer a blessing of unusual power.
Here ends the tale of how astronomy entered the known world.