Fig12_7Spiral_shape_M51.jpg

Fig12_7Spiral_shape_M51.jpg

Fig. 12.7 . Lord Rosse (1800-1867) discovered the spiral structure of Messier 51, abbreviated M 51, using his 1.8-m (72-inch) telescope in the spring of 1845, and he subsequently found at least a dozen other nebulae with a spiral shape. In his description of this drawing of M 51, published in 1850, Rosse attributed the spiral pattern to rotation of the nebula. Camille Flammarion (1842-1925) included this sketch in his popular books about astronomy, leading to a growing awareness of spiral nebulae, and it might have inspired the swirls of starlight found in Vincent Van Gogh’s (1853-1890) painting of the Starry Night. We now know that M 51, also designated NGC 5194 and called the Whirlpool Galaxy, is a magnificent, rotating spiral galaxy located 35 million light-years away, with a small, irregular companion NGC 5195 separated from the center of M 51 by about 10 million light-years. [Reproduced from The Earl of Rosse, Observations of the Nebulae, Philosophical Transactions of the Royal Society, pages 110-124, plate 35 (1850).]

Copyright 2010, Professor Kenneth R. Lang, Tufts University