Trying to measure our place in space is one of those things astronomers have done many different times, and many of those different times, we’ve discovered weird stuff.

In 1914, Vesto Slipher measured our place relative to the motions of fifteen different galaxies. He expected that all the galaxies would be moving randomly compared to our own system, just milling around with nothing particularly unique going on. Instead, he discovered that the majority of galaxies are moving away from us. This seemed to imply that either we are in a unique place – centered in a group of galaxies that appear to be running from us – or, as Hubble would go on to explain, we are in an expanding universe.

In the 1960s, the cosmic microwave background (CMB) was discovered, and over the following years, we worked to measure our place relative to this background light. A motion of 368 kilometers per second was discovered, helping us confirm our galaxy’s motion as we fall toward the Virgo cluster, and also showing motion toward a great hidden cluster lost behind the light and dust of our Milky Way. Again — from the measured motions we learned new things.

As our equipment has improved, researchers have worked to refine our place in space, as well as the positions and motions of all the galaxies around us. Our location inside a galaxy makes this task hard. Dust and gas block our view of the universe beyond the galaxy’s disk, and our galaxy’s bulge takes out an expanded section of the sky. Astronomers attempting to understand the overall layout and motion of galaxies at great distances have had to work around these opaque areas.

Researchers anticipated that distant galaxies would, on average, not be moving relative to the cosmic microwave background. Like us, some would be falling toward clusters, and others would be merging with neighbors. Overall, though, we should see an expanding universe that doesn’t have any great flows of galaxies relative to the background material.

But in initial studies, that is not what anyone saw. Instead, it appeared that we had one motion compared to background galaxies and another motion compared to the cosmic microwave background. And no one could elegantly explain this.

But the data being used wasn’t great. As I said, our galaxy has large opaque areas that don’t let us see the universe beyond. Or at least it doesn’t in the colors of visible light our eyes can see.

Just like an action hero might use infrared goggles to peer through walls to see the warm bodies of people within, astronomers can use radio waves to pierce through the dust and gas and see what lies beyond. And that is exactly what researcher Jeremy Darling did using data from the Very Large Array Sky Survey (VLASS) and the Rapid Australian Square Kilometer Array Pathfinder Continuum Survey (RACS).

These two radio surveys provide data on the northern and southern hemispheres of the sky, and with them, Darling was able to – for the first time – get an accurate perspective on how our galaxy fits in with its most distant surroundings. And in these new results, he found that “it lines up with the early universe from the cosmic microwave background, and it has the right speed.”   For the first time, we got a solid perspective on our place in space and found there is actually nothing weird at all. ‘Not weird’ doesn’t win Nobel Prizes, usually, but it is comforting at times to know science is sciencing correctly.

Darling’s findings do differ from past results and will need follow-up from other teams, but for now, I’m pleased with this result and I have to say I hope it stands up to the tests of time.

More Information

University of Colorado Boulder press release

“The Universe is Brighter in the Direction of Our Motion: Galaxy Counts and Fluxes are Consistent with the CMB Dipole,” Jeremy Darling, 2022 May 26, The Astrophysical Journal Letters