Science: The History of Our Galaxy

The Story:

In new research, astronomers at the Max-Planck Institute for Astronomy have proposed that the galaxy that includes our own solar system, known as the “Milky Way,” has a complicated history. This history began about 13 billion years ago, only 800 million years after the Big Bang, and the highlights reel would include a merger, when about 11 billion years ago the “ancient Milky Way” meshed with the Gaia-Enceladus galaxy.

A New Source of Data:

The name “Gaia,” part of that hyphenated term for the Milky Way’s merger partner, comes ultimately from mythology but more immediately from the European spacecraft of that name launch by the European space agency in April 2018. Gaia has the hardware for observation, and she has released a huge quantum of new information from the sky.

Strange New Worlds:

The Milky Way hasn’t had any more full-on mergers of late, but it still receives immigrants, scientists say. It is tempting to think of our galaxy as at equilibrium. But it is a chaotic place if one takes a Big Picture.

A pair of “dwarf galaxies” seems even now to be closing in on the Milky Way. An astronomer at the University of Virginia has clocked the clouds (known as the Large and Small Magellanic Clouds) as moving inward at about 330 kilometers per second. A writer at QUANTA describes that as “coming in hot.”


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