Johannes Wilsing (8 September 1856 – 23 December 1943) was a German

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

. He was born in

Berlin Berlin ( , ) is the capital and List of cities in Germany by population, largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's List of cities in the European Union by population within ci ...

, where he was educated in addition to

Göttingen Göttingen (, , ; nds, Chöttingen) is a university city in Lower Saxony, central Germany, the capital of the eponymous district. The River Leine runs through it. At the end of 2019, the population was 118,911. General information The ori ...

. In 1880 he was awarded his

Ph.D. A Doctor of Philosophy (PhD, Ph.D., or DPhil; Latin: or ') is the most common degree at the highest academic level awarded following a course of study. PhDs are awarded for programs across the whole breadth of academic fields. Because it is a ...

from Humboldt-Universität of Berlin with a dissertation titled, ''Über den Einfluss von Luftdruck und Wärme auf die Pendelbewegung'' (On the influence of air pressure and heat on the movement of a pendulum). In 1881 he joined the Astrophysical Observatory Potsdam (AOP) as an assistant, and would remain there until he retired. His early career was spent on solar studies, including observations of

sunspot Sunspots are phenomena on the Sun's photosphere that appear as temporary spots that are darker than the surrounding areas. They are regions of reduced surface temperature caused by concentrations of magnetic flux that inhibit convection. Sun ...

s and derivations of the rotation period. In 1897 he measured the parallax of

61 Cygni 61 Cygni is a binary star system in the constellation Cygnus, consisting of a pair of K-type dwarf stars that orbit each other in a period of about 659 years. Of apparent magnitude 5.20 and 6.05, respectively, they can be seen ...

, a relatively nearby star. He became an observer at the AOP in 1898, and the following year he collaborated with

Julius Scheiner Julius Scheiner (25 November 1858 – 20 December 1913) was a German astronomer, born in Cologne and educated at Bonn. He became assistant at the astrophysical observatory in Potsdam in 1887 and its observer in chief in 1898, three years after h ...

in an unsuccessful attempt to measure the

radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmit ...

emission from the Sun. The same year he attempted to interpret the spectrum of novae. He performed extensive work on the luminosity, colors, and diameters of stars. He retired in 1921 and died in

Potsdam Potsdam () is the capital and, with around 183,000 inhabitants, largest city of the German state of Brandenburg. It is part of the Berlin/Brandenburg Metropolitan Region. Potsdam sits on the River Havel, a tributary of the Elbe, downstream of B ...

. The crater Wilsing on the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

is named after him.

External links

Johannes Wilsing

Mathematics genealogy project
1856 births 1943 deaths 20th-century German astronomers 19th-century German astronomers {{Germany-astronomer-stub