Galaxies turn out to be significantly larger than initially believed, stretching vast distances into the depths of space—so extensive 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, this distance is merely insignificant compared to the vastness of space.
The vastness of space is immense. Our home, Earth, orbits a single star located at the periphery of our galaxy among billions of others within the observable universe which contains approximately two trillion galaxies. In essence, space dwarfs everything we know.
The planet Earth is situated within one of the spiral arms of the galaxy. Milky Way (referred to as the Orion Arm) situated approximately two-thirds of the way outward from the center center of the galaxy .
We understand the size of the Earth — measuring at 12,756 kilometers (7,926 miles) in diameter. Similarly, we're aware that the Sun has a diameter of approximately 1,391,000 kilometers (864,400 miles).
However, just how large is our Milky Way galaxy? Up until this point, the actual dimensions of galaxies have been an enigma.
Galaxies exceed our previous expectations in size.
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 their original estimates.
The twisted form of our galaxy that we observe constitutes merely the compact nucleus at its center. In the case of the Milky Way, this central region 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 a galaxy and outer space.
The research has shown that extensive "halos" of gas stretch from the observable spiral patterns of stellar light well beyond into the depths of 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 out into space, significantly expanding our understanding of the size of galaxies.
Kissing galaxies
Actually, the halos of gas from galaxies reach so far into deep space that galaxies themselves extend beyond their visible boundaries. interact with each other .
The research indicates that our Milky Way galaxy is probably interacting with our nearest galactic neighbor, Andromeda—which is approximately 2.5 million light-years distant—according to Nikole Nielsen, the leading author of the study and a researcher at Swinburne University in Australia.
As we observe now, this marks the edge of the galaxy’s sphere of influence,” explained Nielsen in a press release. “It delineates the point at which the galaxy transitions into becoming part of the larger environment around it. Ultimately, it merges with the expansive cosmic web and connects with other galaxies. Such borders tend to be rather indistinct.
Researchers claim that this finding will aid in unraveling one of the most significant mysteries in astronomy: how galaxies develop over time?
Examining the gas halos 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