We finally know when our Milky Way will crash into the Andromeda Galaxy
Our Milky Way galaxy will survive in its current form a bit longer than some astronomers had thought, a new study suggests.
The monster collision between our Milky Way and fellow spiral galaxy Andromeda will occur about 4.5 billion years from now, according to the new research, which is based on observations made by Europe's Gaia spacecraft. Some prominent previous estimates had predicted the crash would happen significantly sooner, in about 3.9 billion years.
"This finding is crucial to our understanding of how galaxies evolve and interact," Gaia project scientist Timo Prusti, who was not involved in the study, said in a statement.

A view of the Andromeda galaxy, also known as M31, with measurements of the motions of stars within the galaxy. This spiral galaxy is the nearest large neighbor of our Milky Way.Credit: ESA/Gaia (star motions); NASA/Galex (background image); R. van der Marel, M. Fardal, J. Sahlmann (STScI)
Gaia launched in December of 2013 to help researchers create the best 3D map of the Milky Way ever constructed. The spacecraft has been precisely monitoring the positions and movements of huge numbers of stars and other cosmic objects; the mission team aims to track more than 1 billion stars by the time Gaia shuts its sharp eyes for good.
Most of the stars Gaia is eyeing are in the Milky Way, but some are in nearby galaxies. In the new study, the researchers tracked a number of stars in our galaxy, in Andromeda(also known as M31) and in the spiral Triangulum (or M33). These neighbor galaxies are within 2.5 million to 3 million light-years of the Milky Way and may be interacting with each other, study team members said.
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