The twice the size of the Milky Way Galaxy is apparently hurtling though the cosmos.
The ultra-hot gas cloud is around 200,000 lightyears wide. To put that into perspective, one light year is about 5.88 trillion miles.
It is believed the wave was formed upwards of a billion years ago, when a small galaxy cluster travelled by the nearby Perseus, another cluster of galaxies, causing gas to slosh around in an empty region of space.
The cloud still remains in Perseus and the discovery was made by analysing data from NASA's Chandra X-ray Observatory.
The gas wave is 200,000 light years across
The Perseus galaxy cluster is located in the Perseus constellation which is some 240 million light years away and around 11 million light years across.
Lead scientist Stephen Walker, from NASA's Goddard Space Flight Center, said: “Perseus is one of the most massive nearby clusters and the brightest one in X-rays, so Chandra data provide us with unparalleled detail.
The gas wave is in the constellation Perseus
“The wave we've identified is associated with the flyby of a smaller cluster, which shows that the merger activity that produced these giant structures is still ongoing.”
As the astronomers were studying the X-ray images, they noticed an odd ‘bow’ shape which kept appearing seemingly from nowhere.
The Perseus galaxy cluster
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They originally concluded that the mysterious object was something to do with a black hole, but upon closer inspection realised that the shape was actually part of the massive wave.
Mr Walker said: "We think the bay feature we see in Perseus is part of a Kelvin-Helmholtz wave, perhaps the largest one yet identified.”