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Primary Sources

3 Nov 2019, 16:07 UTC
Primary Sources
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How do we know that the sun is a star? -- and, that we live in a galaxy full of stars? How do we know what the distances between those stars are? How did we conclude that the moon and planets are illuminated by reflected sunlight, and, not through their own, intrinsic illumination? How do we know how big the universe is, and, of what materials it is composed? By guesswork? By simple reasoning? By concluding what we want to conclude?! No -- never... Vintage Engraving, Early Spectroscope Using Prisms - Drawing by Luisa Vallon FumiThe answers to some of those questions come by way of Newton, Galileo, Herschel, the telescope, and the spectroscope - (and, yes - true, genuine, unadulterated genius, at least, in the case of Newton). To understand these things, one has got to have some grasp, of the long hours of hard work, done by many people - sometimes, extended out, over several generations. But, all of it was done, methodically, one step at a time. Those steps are preserved in records - written at the time, by the very people who took those steps - and exist in the various university libraries, public archives, etc. ...

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