Development of the telescope timeline

3500 BCE

Phonenicians cooking on sand discover glass.
424 BCE

Aristophanes uses a glass sphere filled with water to start fires. Lenses would not be used to study the stars for 2000 years
Period: 1301 to 1400

convex lenses to correct farsightedness are developed
Period: 1401 to 1500

concave lenses to correct nearsightedness are developed
1608

In the Netherlands, Hans Lippershey discovers that holding two lenses up some distance apart bring objects closer. He applies for a patent on his invention.
1609

Thomas Harriot (1560 – 1621) English astronomer, mathematician, ethnographer, and translator becomes the first person to make a drawing of the Moon through a telescope, on July 26, 1609, over four months before Galileo
1609

Galileo, after simply hearing that the device was invented, builds several telescopes of his own and turns them toward the heavens. He dared to publish his findings and was nearly burned at the stake for it.
1611

The term "telescope" is coined by Prince Frederick Sesi at a reception where Galileo is demonstrating his instruments
1611

Johannes Kepler switches from a concave eyepiece to a convex eyepiece. This not only allowed a larger field of view, but it allowed for the projection of images (such as the sun) onto a flat white screen
1636

Marin Mersenne hit upon the idea of using two paraboloidal mirrors instead of lenses, but he never builds this telescope, having been persuaded by Descartes that it could never work.
1637

Rene Descartes demonstrated that speherical lenses cannot produce pinpoints of light.
1663

James Gregory designed a telescope using a concave primary mirror (slightly hyperboloid) concave ellipsoidal secondary mirror. The first mirror gathers the light and reflects it onto the secondary.
1668

Newton produces the first successful reflecting telescope, using a two-inch diameter concave spherical mirror, a flat, angled secondary mirror, and a convex eyepiece lens.
1668

Robert Hooke demonstrates how to shorten the tube by using three or four perfectly flat mirrors to reflect the image back and forth in a shorter tube. A 60-foot long telescope can be reduced to 12 feet long,
1672

Cassegrain proposed a similar design using a convex secondary mirror that allowed the tube to be shortened even more.
1673

Johannus Hevelius realized that the longer the telescope was, the closer together the different colored points of light would be at the focal point, yielding a sharper image.
1675

Christian Huygens suggests getting rid of the supporting structure and mounting the objective lens on the top of a long pole. These were called "aerial telescopes" because they were open to the air
1729

Chester Moor Hall develops an achromatic lens. Two pieces of glass with different indices of refraction can be combined to produce a lens that tends to focus most colors at a very close (though not exact) point
1730

The Scottish Instrument maker James Short invents the first parabolic and elliptic, distortionless mirror ideal for reflecting telescopes. Short accomplished this in a very practical manner.
1757

John Dolland improves upon the achromatic objective lens by placing a concave flint glass lens between two convex crown glass lenses.
1789

ir William Herschel constructs a forty foot long telescope with a four-foot diameter mirror.
1893

H. Dennis Taylor, optical manager of T. Cooke & Sons of York, makers of astronomical telescopes, designed and patented the revolutionary, and now famous, triplet design (British patent no. 1991).

Phonenicians cooking on sand discover glass.

Aristophanes uses a glass sphere filled with water to start fires. Lenses would not be used to study the stars for 2000 years

convex lenses to correct farsightedness are developed

concave lenses to correct nearsightedness are developed

In the Netherlands, Hans Lippershey discovers that holding two lenses up some distance apart bring objects closer. He applies for a patent on his invention.

Thomas Harriot (1560 – 1621) English astronomer, mathematician, ethnographer, and translator becomes the first person to make a drawing of the Moon through a telescope, on July 26, 1609, over four months before Galileo

Galileo, after simply hearing that the device was invented, builds several telescopes of his own and turns them toward the heavens. He dared to publish his findings and was nearly burned at the stake for it.

The term "telescope" is coined by Prince Frederick Sesi at a reception where Galileo is demonstrating his instruments

Johannes Kepler switches from a concave eyepiece to a convex eyepiece. This not only allowed a larger field of view, but it allowed for the projection of images (such as the sun) onto a flat white screen

Marin Mersenne hit upon the idea of using two paraboloidal mirrors instead of lenses, but he never builds this telescope, having been persuaded by Descartes that it could never work.

Rene Descartes demonstrated that speherical lenses cannot produce pinpoints of light.

James Gregory designed a telescope using a concave primary mirror (slightly hyperboloid) concave ellipsoidal secondary mirror. The first mirror gathers the light and reflects it onto the secondary.

Newton produces the first successful reflecting telescope, using a two-inch diameter concave spherical mirror, a flat, angled secondary mirror, and a convex eyepiece lens.

Robert Hooke demonstrates how to shorten the tube by using three or four perfectly flat mirrors to reflect the image back and forth in a shorter tube. A 60-foot long telescope can be reduced to 12 feet long,

Cassegrain proposed a similar design using a convex secondary mirror that allowed the tube to be shortened even more.

Johannus Hevelius realized that the longer the telescope was, the closer together the different colored points of light would be at the focal point, yielding a sharper image.

Christian Huygens suggests getting rid of the supporting structure and mounting the objective lens on the top of a long pole. These were called "aerial telescopes" because they were open to the air

Chester Moor Hall develops an achromatic lens. Two pieces of glass with different indices of refraction can be combined to produce a lens that tends to focus most colors at a very close (though not exact) point

The Scottish Instrument maker James Short invents the first parabolic and elliptic, distortionless mirror ideal for reflecting telescopes. Short accomplished this in a very practical manner.

John Dolland improves upon the achromatic objective lens by placing a concave flint glass lens between two convex crown glass lenses.

ir William Herschel constructs a forty foot long telescope with a four-foot diameter mirror.

H. Dennis Taylor, optical manager of T. Cooke & Sons of York, makers of astronomical telescopes, designed and patented the revolutionary, and now famous, triplet design (British patent no. 1991).