The Earth belongs not only to the Milky Way but also to a “monster” in the galaxy that is incredibly vast.
The bright band we see in the sky, known as the “Milky Way”, was once thought to be the entire galaxy that contains Earth, named Milky Way.
This is a spiral galaxy with a light disk approximately 100,000 light-years in diameter, falling into the category of “monsters” in the galaxy realm, having reached this impressive size by consuming many other galaxies.
However, recent studies gradually prove that the so-called Milky Way is actually much larger, with astonishing structures extending far beyond the starry band we still observe as “the Milky Way.”
The Milky Way is not just the “Milky Way” in our imagination, which appears as a thin, luminous disk filled with stars, but is also surrounded by a halo consisting of two layers: inner and outer, potentially making the actual diameter of the entire galaxy reach up to 2 million light-years – (source: UCSC/NASA/ESA/STScI).
One of the mysteries is the halo, the aura surrounding the main light disk. A recently published study by the University of California, Santa Cruz (UCSC – USA) revealed another surprising point: It’s not just a halo.
According to Sci-News, the research team utilized data from the Next Generation Virgo Cluster Survey (NGVS), conducted using the Canada-France-Hawaii Telescope (CFHT), and identified 208 variable stars not located in the main star disk but within the halo.
Even more astonishing, these stars are located at an incredible distance, with distances from the center of the Milky Way reaching up to 65,000 to 1.05 million light-years.
This indicates that the habitat of stars in the Milky Way must be a disk with a diameter of up to 2 million light-years, even though only the densely star-populated center of the disk can be seen as a bright band from Earth or as a light disk when observed from a planet in another galaxy.
This data also provides valuable information about the halo, a very faint structure that is almost invisible, making it difficult to observe.
“We can use these variable stars as reliable tracking tools to determine distances. Our observations confirm theoretical estimates of the halo’s size.” – Dr. Yuting Feng from UCSC, a member of the research team, stated.
With these results, the complete Milky Way must have a diameter of up to 2 million light-years. Thus, it seems to extend towards the neighboring giant galaxy, Andromeda.
It is possible that these two galaxies are not actually distant since Andromeda is also a “monster” galaxy that may possess an expansive halo like the Milky Way.
This suggests that the Milky Way and Andromeda – two “monsters” expected to collide fiercely in 2 million years – may actually be touching each other in the present. The two billion-year gap is merely the distance for the two bright main disks to approach each other.
Both the Milky Way and Andromeda have consumed many smaller galaxies and peacefully grown, achieving colossal sizes in the galaxy realm to date. However, their collision is expected to cause significant damage to both, as they are equally massive, with Earth predicted to have a risk of being flung out of the “habitable zone” of the Solar System.
