Caption: "This is the sketch made by Lord Rosse of the Whirlpool Galaxy (AKA M51a/NGC 5194 and M51b/NGC 5195) in 1845." (Slightly edited.)
The Whirlpool Galaxy is in constellation Canes Venatici (the Hunting Dogs).
As the image hints, the Whirlpool Galaxy is actually 2 interacting galaxies: (1) NGC 5194/M51a (sometimes called the Whirlpool Galaxy just by itself) which is a large Sc spiral; (2) a smaller companion NGC 5195/M51b which is a peculiar barred lenticular (i.e., an SBO pec), but also classified as a dwarf galaxy.
The Whirlpool Galaxy is about 8.5 Mpc away and 20 kpc in diameter.
The spiral nature of some galaxies (historically these were the spiral nebulae) was first discovered from the Whirlpool Galaxy by William Parsons, 3rd Earl of Rosse (1800-1867) in 1845 April at Birr Castle (Birr (formerly Parsonstown), County Offaly, Ireland) using the Leviathan of Parsonstown (a 1.83 m diameter primary reflector telescope) (CK-366; No-435--437).
Himself circulated a similar sketch at the 1845 June meeting of the British Association for the Advancement of Science.
Himself's own caption for the similar sketch:
Himself and his collaborators with the Leviathan often obtained good accuracy with their sketches (No-437), however, the fine detail is probably Impressionism. They were doing visual astronomy and then probably recreating what they'd seen as soon as possible by light of candle or kerosene lamp.
After Himself's time, J.L.E. Dreyer (1852--1926) worked with the Leviathan 1874--1878. Dreyer would later compile the New General Catalogue (NGC: 1888) and the Index Catalogue (IC: 1895, 1908) of deep-sky objects which include spiral nebulae. Many nearby galaxies are still known by their NGC numbers or IC numbers.
Compare the shown sketch to modern images of the Whirlpool Galaxy in Galaxies file galaxy_whirlpool.html. Other sketches by Himself and collaborators can be seen by image googling lord rosse whirlpool galaxy.
Credit/Permission:
William Parsons,
3rd Earl of Rosse (1800-1867), 1845
(uploaded to Wikipedia by
User:Szdori~enwiki,
2007) /
Public domain.
Image link: Wikipedia: File:M51Sketch.jpg.
Local file: local link: galaxy_whirlpool_lord_rosse.html.
File: Galaxies file:
galaxy_whirlpool_lord_rosse.html.