Percival Lowell detail in mid-1896 soon after the Alvan Clark & Sons refracting telescope was installed at his new Flagstaff, Arizona observatory. Lowell observed the planet high in the daytime sky with the telescope's lens stopped down to 3 inches in diameter to reduce the effect of the turbulent daytime atmosphere. Lowell observed spoke-like surface features including a central dark spot, contrary to what was suspected then (and known now): that Venus has no surface features visible from Earth, being covered in an atmosphere that is opaque. It has been noted in a 2003 "Journal for the History of Astronomy" paper and
Heidelberg-Königstuhl State Observatory in 1906. The observatory ceased to be run by the German federal government in 2005 when it was joined with the Institute of Theoretical Astrophysics and Astronomical Calculation Institute to make up the Center of Astronomy of the University of Heidelberg. Between 1912 and 1957 Karl Wilhelm Reinmuth discovered almost 400 asteroids from the Heidelberg-Königstuhl State Observatory. Heidelberg-Königstuhl State Observatory Heidelberg-Königstuhl State Observatory () is a historic astronomical observatory located near the summit of the Königstuhl hill in the city of Heidelberg in Germany. The predecessor of the current observatory was originally opened in 1774 in the nearby city of