The size of our galaxy has long been a subject of controversy. Every so often, technological advances have helped to redefine its extent. And that is precisely the result of a recent study. The Milky Way is larger than we thought, and we must rethink what we know.
The Milky Way may be larger than previously thought. And it appears to have a more complex radial structure. This is according to a study led by Yunnan University published in Nature Astronomy.

Measuring the radius
Data from stellar spectroscopic surveys were used. The researchers constructed a radial density distribution of stars from the inner to the outer regions of the Galaxy. In this way, they measured the radius of our galaxy.
The result indicates that the structure of the galactic disk in the outer disk region conforms to a classical exponential distribution. Meanwhile, the inner disk region remains almost flat. This finding is distinct from the traditional assumption of a single exponential disk for the galaxy, according to Lian Jianhui, a researcher at Yunnan University, as quoted by Xinhua.
Lian said the study may influence the measurement of key physical properties of the galaxy. Based on past assumptions, the galaxy’s half-light radius, within which half of its luminosity lies, was estimated to be about 10,000 light-years. The radius was extraordinarily small compared to galaxies of similar mass, and therefore the galaxy was classified as a compact galaxy.

A question of size
However, based on the complex density distribution proposed in the study, the galaxy’s half-light radius is 19,000 light-years. This is almost in line with the radius of nearby galaxies of similar mass. This indicates that the galaxy is a typical disk galaxy in terms of size, Lian said.
The Milky Way is bigger than we thought. Lian said the study contributes to understanding the galaxy’s overall structure and evolution. In the future, we will increasingly have much more accurate data about our place in the universe — and the actual space it occupies.