
In the nineteenth century astronomers concentrated increasingly on the notion of the stars and on galactic structure. This required researchers to establish the position in the heavens of enormous numbers of stars as accurately as possible,
This was such a huge undertaking that international cooperation was agreed upon. The Dutch contribution was made by Frederik Kaiser, who in the new Leiden Observatory of 1860 was able to use the most modern telescopes and very accurate clocks.
Thanks to new disciplines such as photometry and spectroscopy astronomers could now for the first time also examine the chemical an physical properties of heavenly bodies. Particularly prominent in the Netherlands was the Utrecht observatory Sonnenborgh where first the sun and later the other stars were studied.


