The Milky Way seen hovering above Morning Glory, a famous hot spring at Yellowstone National Park.
The pristine star formed outside the Milky Way and later drifted into our galaxy.
Without the mass stellar migration, life may not have been able to form on Earth.
There is a lot we have yet to understand about the center of the Milky Way—could it be due to a mass of invisible dark matter?
For decades, astronomers have been vying to identify a source for a mysterious gamma-ray excess at the center of the Milky Way. Could dark matter be the answer?
The finding suggests a pair of gigantic Fermi bubbles in our galaxy formed after the dinosaurs.
The closest galactic relative to the Milky Way helped astronomers discover dark matter in the 1960's.
Photo: Jerry Zhang 
