Or the introduction of the CCD. It produces digital images (which can be analyzed by software automatically), has a linear response to input (so you can reliably measure the brightness of objects), and has much higher quantum efficiency (nearly every photon is detected).
Where to draw the line between modern and pre-modern astronomy is a bit of a subjective question, but there's no doubt that the introduction of the telescope was revolutionary.
Where to draw the line between modern and pre-modern astronomy is a bit of a subjective question, but there's no doubt that the introduction of the telescope was revolutionary.