The Tales Told by Lonely Galaxies

摘要

Laden with 400 billion stars, countless planets, and vast clouds of gas, our Milky Way galaxy pinwheels through the void. Its spiral arms stretch 50,000 light-years and revolve once every 220 million years, as we plunge at 400,000 kilometers per hour toward the neighboring Andromeda galaxy. That's well known, but it's less clear how the Milky Way-or any other galaxy-came to appear as it does.