Galileo's Telescope

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The First Telescopic Observations of a Celestial Object

Galileo's ink renderings of the moon:

the first telescopic observations of a celestial object.

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.

From http://www.nasa.gov/