Here is a look at some of the major milestones in the advancement of telescopes through the last four centuries.

The 1600s

1608  —

Hans Lippershey, a German-Dutch lensmaker once said that he wanted to make an instrument “for seeing things far away as they were nearby.” He was the first person to ever think of the telescope.

 

1609  —

On hearing about this new instrument, Italian physicist Galileo Galilei builds his own. He improved Lippershey’s design and using his new telescope the following year, he discovers the four largest moons of Jupiter (Io, Ganymede, Callisto and Europa), sunspots on the surface of the Sun, the phases of Venus and physical features on the Moon – such as craters!

1616  —  Italian priest and astronomer Niccolo Zucchi creates a concave spherical
mirror (a mirror that bulges inwards – very much like a cave!) to magnify
objects and he used it to discover Jupiter’s belts 14 years later.

1630  —  German priest and astronomer Christoph Scheiner builds a telescope based
on a design that astronomer Johannes Kepler made in 1611. Kepler’s design
improves on Galileo’s by replacing the concave lens with a convex lens (a
lens that bulges outwards). This helped to reduce spherical aberration.
Astronomers find spherical aberration quite annoying as it means that they
do not get perfect images when they look through their telescopes. Imagine
having distorted vision!

1655  —

Inspired by the observations of Jupiter made by Galileo, Dutch astronomer Christian Huygens builds the most powerful telescope ever and uses it to view the planets in our Solar System. He spotted a bright moon in orbit around Saturn and called it “Saturni Luna.” All astronomers used this name until 1847 when John Herschel (famous astronomer William Herschel’s son) decided that the moon should be called Titan. Huygens studied Saturn much more with his telescope and discovered the true shape of the planet’s rings in 1659.

1666  —  After studying the reflection of light through prisms, Sir Isaac Newton
decides that the problem of chromatic aberration cannot be solved. He
makes an improved version of the reflecting telescope.

 

1672  —  Laurent Cassegrain, a catholic priest from France, develops a telescope that
bears his name – the Cassegrain telescope. This instrument uses mirrors that
are called hyperbolic and parabolic mirrors.

The 1700s

1721  —  English mathematician (and inventor of the octant) John Hadley present a
much-improved Newtonian telescope design.

 

1729  —  A huge development in refracting telescope happens during this time when
lawyer Chester Moore Hall makes a lens to reduce chromatic aberration even
further. He made the lens by cementing two types of glass (crown and flint)
together. He proved that Newton’s statement that chromatic aberration could
not be solved was incorrect!

1789  —

Bath (UK) Orchestra Director and astronomer William Herschel builds a Newtonian based reflector telescope which is a gigantic 12-metres. It was the first of the giant reflector telescopes.

The 1800s

1845  —

“Leviathan of Parsonstown” at Birr Castle in Ireland was built in this year by the Third Earl of Rosse, William Parsons. It was the largest telescope ever built until the twentieth century. Parsons was the first person to see spiral arms on a galaxy!

1897  —  American astronomer Alvan Clark builds the world’s largest (at that time!)
existing refracting telescope – the Yerkes Telescope in Wisconsin. Because
this telescope holds the largest glass lens possible before a telescope will
begin to buckle under its own weight, astronomers decided that large
telescopes should have mirrors instead of lenses.

The 1900s

1937  —  Inspired by sky survey work by Karl Jansky, American engineer Grote Reber
takes the telescope into a whole new dimension: the radio telescope. Reber
created an instrument that could basically see radio waves – waves that are
invisible to our eyes.

1957  —

Astronomer Sir Bernard Lovell planned a 250ft radio telescope that could be pointed to anywhere in the sky in the 1950s. After a series of technical and financial problems, it was finally built and ready to be used in the summer of 1957. The telescope can be visited at Jodrell Bank in the UK.

 

1990  —  NASA and ESA’s Hubble Space Telescope, the first telescope to be launched
into space. Above the turbulence of the Earth’s atmosphere, Hubble gives us
a very clear view of the stars and planets right to this very day!

1991  —  The Compton Gamma Ray Observatory becomes the first space telescope to
look at objects that belch out high energy waves called gamma rays.

1995  —

The W. M. Keck Observatory, a two-telescope astronomical observatory, is built near the summit of Mauna Kea in Hawaii at an incredibly dizzy height of 13,600 feet. They are the second largest optical telescopes in the world.

Courtesy W. M. Keck Observatory

The 2000s

2009  —

The Herschel Space Observatory is launched. Bearing the name of astronomer, William Herschel, this space observatory is able to look into the really cold regions of space with its far infrared vision!

2010  —  The Gran Telescopio Canarias is built on the island La Palma in the Canary
Islands of Spain on the top of a volcanic peak 7,438 feet above sea level. It
is the largest telescope of our time.

                               
Gran Telescopio Canarias