Looking Up: A Cosmic Symphony In The Space Between The Galaxies

November 13, 2017

This beautiful image gives a new look at Stephan's Quintet, a compact group of galaxies discovered about 130 years ago and located about 280 million light years from Earth.

This week a quintet of galaxies takes center stage on Looking Up.

What would you say if I told you there was a beautiful quintet available to you, right now? Would you reach for your headphones? Well, in this case, it’s not a lovely musical interlude, but rather an amazing and beautiful grouping of galaxies high in the Colorado night sky, called Stephan’s Quintet.

First recorded by Edourad Stephan in 1877, this group of five galaxies is both beautiful to look at, and kind of freaky to understand. It seems four of the five galaxies are tightly bound to each other gravitationally. Indeed, there is evidence that before too many more billions of years pass, they will all collapse into one huge galaxy.

But that’s not the strangest part. In the 1970s, astronomers detected what seemed to be a strange and mysterious filament of something emitting radiation in the space between the galaxies. More advanced telescopes in recent years let us see that this filament is actually a massive, inter-galactic shock wave, like a sonic boom on Earth, heating the intergalactic gases to millions of degrees. This is likely due to one of the galaxies smacking into the gas between the other galaxies. And as shock waves go, this one is a biggie – it’s already bigger than our own Milky Way galaxy. So, if you are planning a trip to Stephan’s Quintet, be sure to try to catch a wave.

This false-color composite image of the Stephan's Quintet galaxy cluster clearly shows one of the largest shock waves ever seen (green arc). The wave was produced by one galaxy falling toward another at speeds of more than one million miles per hour. The image is made up of data from NASA's Spitzer Space Telescope and a ground-based telescope in Spain.

If you’d like to take a closer look at Stephan’s Quintet or any of the wonderful and amazing things in the sky, please visit csastro.org for a link to information on our monthly meetings and our free public star parties.