Jacobus Cornelius Kapteyn was a Dutch astronomer. He carried out extensive studies of the Milky Way. He found that the apparent movement of stars was not randomly distributed but had two preferential directions: the two star streams. This discovery was later reinterpreted as evidence for galactic rotation. Kapteyn also suggested that these stellar velocities could be used to find the amount of non-luminous matter in the galaxy, which his student, Jan Oort, measured in 1932, referring to it as "invisible matter".
Jacobus Kapteyn, Dutch astronomer and academic (born 1851)
On June 18, in the year 1922, Jacobus Kapteyn, Dutch astronomer and academic (born 1851). This event is recorded as a Notable Deaths event in the history of June 18, one of 453 recorded events on this date across all of history.
1 notable person is associated with this event, including Jacobus Kapteyn. Learn more below.
Key Facts
- This event took place on June 18, 1922 (AD era).
- It is categorised as a Notable Deaths event in recorded history.
- Referenced in 1 Wikipedia article.
- 1 notable person is recorded as involved in or associated with this event.
- Wikipedia source last updated on 30 April 2026.
On This Date in History 453
This article draws on content from Wikipedia, available under CC BY-SA 4.0.
People Involved
More on June 18
Edward Brooker, English-Australian politician, 31st Premier of Tasmania (born 1891)
William Edward Brooker was a Labor Party politician. He became the interim Premier of Tasmania on 19 December 1947 while Robert Cosgrove was facing corruption charges. He died on …
Edward Brooker, English-Australian politician, 31st Premier of Tasmania (born 1891)
Shigematsu Sakaibara, Japanese admiral (born 1898)
Shigematsu Sakaibara was an admiral in the Imperial Japanese Navy, the Japanese garrison commander on Wake Island during World War II, and a convicted war criminal. He was respon…
Shigematsu Sakaibara, Japanese admiral (born 1898)
Florence Bascom, American geologist and educator (born 1862)
Florence Bascom was a pioneer American woman geologist and educator. Bascom was the second woman to earn a PhD in geology in the United States. She received her PhD in 1893 from…
Florence Bascom, American geologist and educator (born 1862)
Simon Bolivar Buckner Jr
Simon Bolivar Buckner Jr. was a lieutenant general in the United States Army during World War II who served in the Pacific Theater. As commanding general of Alaska Defense Command…
Simon Bolivar Buckner Jr
Elias Degiannis, Greek commander (born 1912)
Ilias Degiannis was a Greek navy officer Resistance leader during the Axis occupation of Greece.
Elias Degiannis, Greek commander (born 1912)
Arthur Pryor, American trombonist, bandleader, and politician (born 1870)
Arthur Willard Pryor was a trombone virtuoso, bandleader, and soloist with the Sousa Band. He was a prolific composer of band music, his best-known composition being "The Whistler…
Arthur Pryor, American trombonist, bandleader, and politician (born 1870)
Comments 0
Sign in to join the discussion.