Early Telescopes
In the early 1600's, Galileo created a telescope to observe the night sky.
A new era in astronomy began.
Kepler invented an improved refracting telescope.
He figured out that the orbits of planets were elliptical not circular.
This discovery helped to complete the heliocentric model of our Solar System.
Isaac Newton was the first to invent a reflecting telescope.
It used a concave mirror instead of a lens.
As more people observed the sky with telescopes, many more discoveries were made.
Things that were previously invisible with the naked eye were now visible.
In 1781, William Herschel discovered the planet Uranus, as well as some diffused faint objects.
Charles Messier made a catalog of such objects, now called the Messier Catalog.
Messier discovered M51 with a relatively small telescope, recording it as a faint nebulous cloud.
John Herschel, the son of William Herschel illustrated a ring with something faint next to it
- after observing it with a mirror-based reflecting telescope a little under half a meter diameter.
To get a closer look at faint objects, larger telescopes are needed.
The spiral arms of M51 became visible when observed with
William Parsons' 1.8 m diameter mirror. Named “Leviathan of Parsonstown”
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