25 Greatest Astronomical Findings

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THE 25 greatest astronomical findings of all time, according to the editors of Astronomy magazine (October 1998) are as follows:

1. the discovery of quasars (1963);

2. the cosmic microwave background (1965-66);

3. § pulsars (1967);

4. Galileo's observations of the phases of Venus, Jupiter's moons, and craters on the moon (c 1609);

5. extrasolar planets (1992);

6. § supermassive black holes (early 1990s);

7. Newton's Principia, formulating the mathematics of our heliocentric system (1687);

8. the discovery of Uranus (1781);

9. the first known asteroid (1801);

10. discovery of Pluto (1930);

11. Neptune (1846);

12. spectroscopic proof that nebulae are gaseous in nature (1864);

13. recognition of galaxies beyond our own (1923);

14. the advent of radio astronomy (1931-32);

15. studies of globular clusters help to map the Milky Way (1918);

16. cometary explosion over Siberia (1908);

17. an accurate measurement of the speed of light (1675);

18. Southern Hemisphere celestial objects cataloged (1834-38);

19. Cepheid-variable period-luminosity relationship worked out (1912);

20. Copernicus' De Revolutionibus sets forth the heliocentric system (1543);

21. Laplace's theory on how the solar system formed (1796);

22. a transit of Venus suggests Venus has an atmosphere (1761);

23. § the Hertzsprung-Russell diagram for understanding how stars age (1913);

24. § scheme for classifying star types (1890);

25. the use of parallax for finding a star's distance from Earth (1838).