© Hubble Space Telescope/NASA/ESA, H. Bond (STScI) and M. Barstow (University of Leicester)Sirius A and its faint companion, Sirius B.
As has often been pointed out, by definition the uniformitarian creed precludes the very real possibility of rare and radical changes in nature.
Since the late 19th century, most geologists have fondly embraced the adage of the British lawyer and geologist, Sir Charles Lyell (1797-1875): 'The present is the key to the past.' Its naïve implication is that all phenomena that ever happened in nature still occur today and can be observed. Historical evidence is valuable precisely because it offers an even better key to the past than present-day analogues: eye-witness accounts.
A prime application of the historical method concerns the colour of Sirius A or α Canis Majoris, the brightest star in the night sky. Sirius appears bright white today, but - as the English amateur astronomer, Thomas Barker (1722-1809), first pointed out in 1760 - was emphatically qualified as red in many classical texts. Poetical passages aside, Seneca commented that Sirius was of a deeper red than Mars, while Ptolemy labeled the star "reddish" and grouped it with five other stars, all of which are indeed of red or orange aspect.
Even as late as the 6th century CE, the Gallo-Roman chronicler, Gregory of Tours, could label the Dog Star rubeola or 'reddish'. It is claimed that the earliest unambiguous reference to Sirius as a white star is found in the pages of the Persian astronomer, 'Abd al-Raḥman al-Sufī (903-986 CE).
