1845 ⟶ Construction of a Large Reflecting Telescope
Irish astronomer William Parsons, 3rd Earl of Rosse complete...Year
1843
1845
1846
1992
☀️ Discovery of Sunspot Cycle
German amateur astronomer Heinrich Schwabe, who had been studying the Sun for the past 17 years, announces his discovery of a regular cycle in sunspot numbers - the first clue to the Sun's internal structure.⟶

AstronomySolar PhysicsSunspotsHeinrich Schwabe19th CenturySolar CycleAstronomy

🔭 Construction of a Large Reflecting Telescope
Irish astronomer William Parsons, 3rd Earl of Rosse completes the first of the world's great telescopes, with a 180-cm mirror. He uses it to study and draw the structure of nebulas, and within a few months discovers the spiral structure of the Whirlpool Galaxy.⟶

AstronomyTelescopeWilliam ParsonsObservational Astronomy19th CenturyNebulaeWhirlpool Galaxy

📸 Early Astrophotography of the Sun
French physicists Jean Foucault and Armand Fizeau take the first detailed photographs of the Sun's surface through a telescope - the birth of scientific astrophotography. Within five years, astronomers produce the first detailed photographs of the Moon. Early film is not sensitive enough to image stars.⟶

AstronomyAstrophotographyJean FoucaultArmand FizeauPhotography19th CenturySunMoon

🪐 Discovery of Neptune
A new planet, Neptune, is identified by German astronomer Johann Gottfried Galle while searching in the position suggested by Urbain Le Verrier. Le Verrier has calculated the position and size of the planet from the effects of its gravitational pull on the orbit of Uranus. An English mathematician, John Couch Adams, also made a similar calculation a year earlier.⟶

AstronomyPlanetary ScienceNeptuneUrbain Le VerrierJohn Couch AdamsJohann Gottfried Galle19th CenturyCelestial MechanicsGravitation


🔭 Keck Telescope Completed
The 10-meter Keck telescope on Mauna Kea, Hawaii, is completed. The first revolutionary new wave of telescopes, the Keck's main mirror is made of 36 six-sided segments, with computers to control their alignment. New optical telescopes also make use of interferometry – improving resolution by combining images from separate telescopes.⟶

AstronomyTelescopeOptical AstronomyKeck TelescopeMauna KeaInterferometry