History of Telescope

In 1609 an Italian physicist and astronomer named Galileo became the first person to point a telescope skyward. Although that telescope was small and the images fuzzy, Galileo was able to make out mountains and craters on the moon, as well as a ribbon of diffuse light arching across the sky -- which would later be identified as our Milky Way galaxy. After Galileo's and, later, Sir Isaac Newton's time, astronomy flourished as a result of larger and more complex telescopes. With advancing technology, astronomers discovered many faint stars and the calculation of stellar distances. In the 19th century, using a new instrument called a spectroscope, astronomers gathered information about the chemical composition and motions of celestial objects.
Twentieth century astronomers developed bigger and bigger telescopes and, later, specialized instruments that could peer into the distant reaches of space and time. Eventually, enlarging telescopes no longer improved our view… all because of the Earth's atmosphere.
A Telescope in the Sky? Why?
The next time you gaze up at the night sky, you're likely to spot a twinkling star. But is it really twinkling? What looks like a twinkling star to our eyes is actually steady starlight that has been distorted, or bent, by the Earth's atmosphere. The visual effect of this distortion is like looking at an object through a glass of water.
Telescopes here on the ground -- which also must peer through Earth's atmosphere -- are equally vulnerable to our atmosphere's visual tricks.
That's why astronomers around the world dreamed of having an observatory in space -- a concept first proposed by astronomer Lyman Spitzer in the 1940s. From a position above Earth's atmosphere, a telescope would be able to detect light from stars, galaxies, and other objects in space before that light is absorbed or distorted. Therefore, the view would be a lot sharper than that from even the largest telescope on the ground.