By mid-1609, Galileo was working on his treatise about the science of motion, when upon hearing of the invention of the spyglass (the precursor to the telescope) he dropped everything to make his own version. By the end of August, Galileo had a 9X telescope. Around December 1, 1609, Galileo had in his possession a 20X telescope, allowing him to observe the moon’s rough mountainous surface, four (of the currently sixty-seven known) moons of Jupiter, and several new stars.
In mid-1609 Galileo turned his focus away from the laws of motion and pointed his telescope towards the sky.
Galileo put his original work on the laws of motion on hold for 25 years to focus on his passion with astronomy.