Galaxies turn out to be significantly larger than initially believed, stretching vast distances into deep space—distances so great that our home galaxy, the Milky Way, probably comes into contact with our nearest galactic neighbor, Andromeda.
As you might believe, the journey to the drugstore seems quite lengthy," penned Douglas Adams in The Hitchhiker's Guide to the Galaxy, "however, compared to space travel, this distance is merely insignificant.
The vastness of space is immense. Our home, Earth, resides as an insignificant speck circling a star located at the periphery of our Milky Way, which itself is merely one among approximately two trillion galaxies in the observable cosmos. Indeed, space spans an extraordinarily large expanse.
The planet Earth is situated within one of the spiral arms of the galaxy. Milky Way (referred to as the Orion Arm) which is located approximately two-thirds of the way out from the center center of the galaxy .
We are aware of the size of the Earth — approximately 12,756 kilometers (7,926 miles) in diameter. Similarly, we know the dimensions of our Sun, which is roughly 1,391,000 kilometers (864,400 miles) across.
However, just how vast is the Milky Way? Up until this point, the actual dimensions of galaxies have been an enigma.
The size of galaxies exceeds our expectations.
A recent research paper, featured in the journal Nature Astronomy It has been discovered that galaxies are much larger than initially believed, possibly even multiple times greater in size.
The coiled shape of our galaxy constitutes merely its compact central region. In the case of the Milky Way, this spiral spans approximately 100,000 light-years.
The starlight emanating from stars located within the spiral arms reaches approximately 7,800 light-years out into the vastness of space, marking what was once believed to be the boundary between the end of a galaxy and the start of deep space.
The research has shown that extensive "halos" of gas stretch beyond the observable spiral arms of stars deeply into outer space.
Astronomers were able to observe these gaseous halos for the first time thanks to advanced imaging technologies. These techniques allowed scientists to identify galactic gas halos extending more than 100,000 light years into space, significantly expanding our understanding of galaxy sizes.
Kissing galaxies
Actually, the halos of gas surrounding galaxies reach such vast distances into deep space that the galaxies themselves extend outwards considerably. interact with each other .
The research indicates that our Milky Way is probably colliding with our nearest neighboring galaxy, Andromeda — which is approximately 2.5 million light-years distant, as stated by Nikole Nielsen, the lead author of the study and a researcher at Swinburne University in Australia.
"We’re now observing the limits of the galaxy’s influence, the point at which it transitions into becoming part of the environment surrounding it, and ultimately merging with the larger cosmic web along with other galaxies. These borders tend to be rather indistinct," explained Nielsen in a press release.
Researchers believe this finding will aid in unraveling one of the most significant mysteries in astronomy: how galaxies develop over time?
Examining the gaseous envelopes surrounding various kinds of galaxies — those form stars , or those that no longer form stars—will aid in understanding how galaxies accumulate mass over time and the effects they have on one another during interactions.
Edited by: Andreas Illmer
Primary source:
Nielsen, N.M., et al. A map showing emissions from the interface between the disk and circumgalactic medium in the starburst galaxy IRAS 08339+6517. Nature Astronomy (2024). https://www.nature.com/articles/s41550-024-02365-x
Author: Fred Schwaller
