Forty years later, American astronomer Edward Fath revisited Abbe’s question. After measuring the orientations of hundreds of galaxies on photographic plates taken at Mount Wilson Observatory, he reported in 1914 that they “appear to be oriented at random.”







Why are galaxies elongated?



Most galaxies are elongated in shape; round ones are rare. But why?



A galaxy’s image is a snapshot of its stars’ motions, a moment frozen in time. Spiral galaxies like the Milky Way owe their flattened shapes to rotation. Just as a ball of pizza dough flattens when spun, a spiral galaxy’s stars spread into a thin disk as it rotates. Traveling at half a million miles per hour, our Sun has made nearly two dozen trips around the Milky Way since its birth.

Elliptical galaxies, on the other hand, have little or no rotation. Their stars swarm around the galaxy’s center like bees around a hive, each following its own seemingly random path. However, these orbits are often elongated in one direction more than others, stretching the galaxy into a shape resembling a luminescent football. — M.W.

Then in 1968, Gummuluru Sastry of Wesleyan University showed beyond any doubt that the orientations of some galaxies are clearly not haphazard. Sastry discovered that giant elliptical galaxies that populate the centers of clusters — the biggest and brightest galaxies in the universe — have a remarkable tendency to be elongated in the same direction as their host cluster. For example, if a cluster is elongated north-south, then more often than not, its brightest member galaxy is, too. If galaxies were human, psychologists would call this a textbook example of mirroring behavior.





Although Sastry’s conclusion was based on only five galaxies, other astronomers have subsequently confirmed his results with much larger samples. Recent studies with the Hubble Space Telescope — whose sharp vision allows us to see the remote past by looking far into space — reveal that these alignments even existed billions of years ago.

Decades of lively debate followed. English amateur astronomer Francis Brown spent more than 30 years investigating galaxy alignments in his spare time. In a series of papers published between 1938 and 1968, he presented evidence that galaxy orientations in certain regions of the sky were far from random. But many astronomers remained skeptical, suggesting that the results might be a consequence of measurement errors, selection effects, or even psychological biases.