What did galileo teach about the value of observing and experimenting?

Galileo was not the first to indicate the telescope the skies, the first being presumably Thomas Harriot, who was additionally the primary we are aware of making lunar maps and taking a gander at sunspots. Be that as it may, he didn't distribute thus he died. 
Then again we have the Tuscan who, in the unhinged months that saw the telescope spreading in Europe and being utilized by space experts out of the blue, practically raced to the press the Sidereus Nuncius that contained the galactic disclosures that gave him wide and sudden acclaim.