Dutch astronomer Jacobus Kapteyn was born #OTD in 1851.
Kapteyn spent much of his life counting stars and measuring their magnitudes and proper motions, with a goal of determining the shape and size of the Galaxy. He concluded after decades of work that the Galaxy was about 30,000 light-years across and perhaps 10,000 light-years thick, with the Sun not too far from the center. His model of the universe came to be called the Kapteyn universe. via @LindaHall_org
@gutenberg_org The Milky Way is about 1,000,000,000,000,000,000 km (about 100,000 light years or about 30 kpc) across. The Sun does not lie near the center of our Galaxy. It lies about 8 kpc from the center on what is known as the Orion Arm of the Milky Way.
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