No. 81: May-Jun 1992
We have all seen impressive photographs of spiral galaxies with their whirlpool patterns. One can easily imagine them spinning ponderously, with streams of stars spiraling out behind the rotating core. This picture is intuitively satisfying from a mechanical point of view. But:
"A galaxy with a spiral arm going the wrong way has been found by astroomers in the U.S. Spiral arms usually trail behind as a galaxy turns, but in NGC 4622 an inner arm is wrapped round the galaxy in the direction it is rotating."
(Mitton, Simon; "Puzzle of Galaxy That Points Two ways," New Scientist, p. 22, February 29, 1992.)