The Earth Resides on the Edge of a Galaxy-Devouring Monster with a More Terrifying History than Imaginable.
The Gaia Spacecraft from the European Space Agency (ESA), a satellite primarily tasked with mapping the Milky Way galaxy where Earth is located, has made a shocking discovery in the galaxy’s halo.
The Milky Way is one of the ancient and colossal galaxies in the universe. To achieve its impressive size today, scientists believe it has undergone over 20 mergers with other galaxies during its “youth.”
The “monster” Milky Way that houses Earth has attained its grand size through dozens of previous galaxy merger events – (Graphic: SCIENCE NEWS).
According to Sci-News, astronomers previously believed that the final merger occurred with the Gaia-Sausage-Enceladus event, around 8 to 11 billion years ago.
However, data from Gaia’s third data release now indicates that another galaxy merger event happened much more recently.
This event, named the “Virgo Radial Merger”, occurred only 2.7 billion years ago, suggesting that the Milky Way has exhibited its “monster” behavior for a significant part of its life.
The evidence left behind by the event includes several “wrinkles” in the halo along with unusual star movements that Gaia has just recorded.
Researchers from Rensselaer Polytechnic Institute and the University of Alabama (USA) – who identified the unusual signs from the Gaia data – stated that this was determined by analyzing the movements of 100,000 stars near us.
The unusual “wrinkles” left in the galaxy will gradually fade over time, so calculations based on these distinctive, non-uniform characteristics help the authors estimate the ages of merger events.
At the time when the Milky Way monster was its most voracious, around 8 billion years ago, the number of wrinkles seemed to be layered closely together.
The Virgo Radial Merger event is a significant merger that involved a group of several smaller dwarf galaxies and star clusters, joining the Milky Way simultaneously.
Thus, the ripples caused by this event still exist prominently.
“The history of the Milky Way is continuously being rewritten at the present moment, largely thanks to new data from Gaia,” said Dr. Thomas Donlon, a co-author.
