Astronomy: Post-Newtonian Astronomy

In the 1700's and 1800's, science (or 'natural philosophy') continued to develop and grow. Growth in astronomy was assured by the continued application of the telescope, and better telescopes were always being manufactured. In telescope-making, "bigger" is usually "better". Observatories were built. Observatoire de Paris 1671, Royal Observatory in Greenwich 1676, Royal Observatory of Berlin 1700. Private observatories were built by William Herschel (1780) and the Earl of Rosse (1825). The Imperial Observatory of Russia was built in 1839, and in the United States, Lick Observatory (1888) and Yerkes Observatory (1897), both funded by private donors.

In the middle 1800s both the spectrograph (prism, by which different colors [wavelengths] are spread out) and the photographic plate caused great advances in astronomy. William Huggin (1864) took the first photograph of the spectrum of a star (besides the sun, which is bright enough to have been studied by eye). These spectra are bright washes of light except for dark notches at specific wavelengths. This is an absorption line spectrum, which looks just like a continuous spectrum except that no dark lines are seen in a continuous spectrum. Parallel laboratory work, in which spectra were obtained from the glow from superheated materials, showed emission line spectra whose bright lines corresponded in wavelength exactly with the dark lines seen in stars. For instance, the twin lines of sodium at 595nm wavelength are seen in laboratory flames, the sun, and many stars. We had discovered that the universe of stars shared a common chemistry with the earth.

There are a host of developments in physics in the 1800s that we will mostly skip. Here are the highlights, selected for direct relevance to astronomy.

Last modified: Wed Oct 4 22:24:42 CDT 2000