“In the morning . . . while standing on an ice hummock about seventeen feet high, and looking toward the east, I had observed the upper limb of the sun, as it filled a triangular cleft on the ridge of the headland, of the most brilliant emerald colour, a phenomenon which I had not witnessed before in these regions.”

—Captain Back; J. Murray, Captain Back’s narrative of the voyage of the H.M.S. Terror, 1838.