How do we know what stars, gas clouds and galaxies are made of? How do we know how fast they are moving?  Indeed how do we know anything much at all about our Universe, and what does William Huggins have to do with any of this?

The answer is spectroscopy, the science of dispersing light from a particular source into a spectrum of colours and observing the dark lines (in an absorption spectrum) or bright lines (in an emission spectrum).  This is the fundamental tool of astronomy.

The story starts in 1666 when Newton observed the spectrum produced by a prism and concluded that the resulting colours were present in the white light from the source.  Dark lines were discovered in the spectrum in 1802 by William Hyde Wollaston and investigated more systematically in 1814 by Joseph von Fraunhofer.  William Huggins took this much further forward by combining spectroscopy with photography.  The contribution of his wife Margaret will also be acknowledged: she encouraged her husband’s photography and helped to put their research on a systematic footing.

Thus William and Margaret Huggins were able to distinguish between nebulae which have the spectral characteristics of gas and galaxies which have the spectral characteristics of stars. This was a step towards proving that galaxies are whole separate star systems.  They also observed the redshift of Sirius in 1868 which they interpreted as being due to the star moving away from us.

Join our talk on William Huggins this Friday at 7.30pm (either live at Queen Square or online) and discover more about the amazing discipline of spectroscopy!

Book Here:

https://www.brlsi.org/whatson/reaching-across-the-gulf-of-space-william-huggins-at-200/