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    Timelines – Telescopes

    Era/YearTelescope TypeDescription
    1608Dutch TelescopeFirst device identified as a telescope. Made by Hans Lippershey and was a refracting telescope with convex objective and eyepiece lenses.
    1609Galilean TelescopeGalileo Galilei improved the invention, and this telescope could magnify objects up to three times.
    1611Keplerian TelescopeInvented by Johannes Kepler, it used a convex objective lens and a convex eyepiece. Allowed for higher magnification and a larger field of view.
    Late 17th CenturyNewtonian TelescopeIsaac Newton developed a telescope that used mirrors – a reflecting telescope. This type of design minimised the colour distortion.
    18th CenturyHerschelian TelescopeThis simpler design incidentally made by William Herschel has a slight tilt in the mirror to avoid the observer’s head from obstructing the viewing.
    19th CenturyCassegrain telescopeLaurent Cassegrain designed the light path which involves reflection off the back of the primary mirror and a hole in the centre of primary mirror.
    Mid 20th CenturyRadio telescopesThese could observe radio waves from space. Radio telescopes opened a new window into the study of the universe.
    Mid 20th CenturySpace TelescopesTo escape the distorting effects of Earth’s atmosphere, telescopes like Hubble were sent to orbit.
    Early 21st CenturyDigital/Robotic telescopesMore efficient to observe as they could sample multiple wavelengths, not just visible light. Greatly increased data availability.
    CurrentExtremely Large Telescopes (ELT)Under development, these telescopes are ground-based and have significantly larger mirrors with diameters up to 39 metres.