At the age of 12 Anton borrowed a textbooks from his brother and studied the constellation Gemini, where he noticed an extra point of light.

[2] After reading Edward Bellamy's Equality, Pannekoek became a convinced socialist and started studying the philosophies of Karl Marx and Joseph Dietzgen.

Soon Pannekoek became a well-known Marxist writer, writing for both Dutch and German socialist magazines, like Die Neue Zeit.

His astronomical and socialist careers first clashed when he was reprimanded for leading a strike support committee and was treated with dismissal from his job at the observatory by the Dutch government.

[4] Pannekoek was offered the option to become a lecturer in historical materialism at the school funded by the Social Democratic Party of Germany.

Prevented from returning to Germany, he started work as a cosmography and science teacher for secondary schools and a privaatdocent in history of astronomy at Leiden University.

[7] Though Willem de Sitter wanted to hire him as assistant director at the Leiden Observatory in 1918, the appointment was prevented by the Dutch government because of his outspoken Marxist sympathies.

In his theoretical research, Pannekoek explored ways to expand upon Meghnad Saha's ionization formula to better understand the physical conditions in the outer layer of stars.

One of his main conclusions was that the narrow spectral lines in c-type stars, as found by Antonia Maury, were most likely caused by lower pressure in the stellar atmospheres.

[17] He and his students also published comprehensive catalogues of the spectral lines in late type stars based on photographic plates taken by Pannekoek at the Dominion Astrophysical Observatory in 1929.

[22] His work in galactic structure, astrophysics and the history of astronomy was of international renown and won him an honorary degree from Harvard University in 1936, as well as the Gold Medal of the Royal Astronomical Society in 1951.

[24] Defunct A recognized Marxist theorist, Pannekoek was one of the founders of council communism and a main figure in the radical left in the Netherlands and Germany.

He regarded these as a new form of organisation capable of overcoming the limitations of the old institutions of the labour movement, the trade unions and social democratic parties.

During the early years of the Russian revolution, Pannekoek gave critical support to the Bolsheviks, a position shared by fellow council communist Herman Gorter.

[27] He put his views forward in his 1938 book Lenin als Philosoph, originally published in German under the pseudonym J. Harper.