FOCUS History of twentieth century astronomy

摘要

The twentieth century was a watershed in astronomy. Over a hundred years so much changed, so much was learnt, so much was improved that it is impossible to compare astronomy in the Victorian age to the realms that astronomical research explores today. Whereas in the year 1900 astronomers believed that the Milky Way was the entirety of the Universe, in 2000 we now know that our Galaxy is just one of countless trillions in a cosmos that stretches all the way back through 13.81 billion years of history. Whereas in 1900 the largest telescope in the world was the 1.83-metre Leviathan at Birr Castle, in 2000 it was the twin ten-metre Keck telescopes, with 30, 40 and even 100 metre telescopes on the horizon, while telescopes also stargaze in space, high above the thick atmosphere. Meanwhile, planets were remote worlds in 1900, seemingly out of our reach, but by 2000 a probe had visited every planet (and one is currently speeding towards that ex-planet, Pluto). The twentieth century also saw a sea-change in how astronomy is conducted, from individual bright sparks making singular giant theoretical leaps that change the course of science - Albert Einstein being the obvious personality, but we can also throw in people like Edwin Hubble - to vast collaborative efforts that make many incremental advances through surveys and large multinational experiments.