Using data from Fermi's Large Area Telescope, scientists have discovered a gigantic, mysterious structure in our galaxy. This never-before-seen feature looks like a pair of bubbles extending above and below our galaxy's center, as shown in false color in this figure.
Each lobe is 25,000 light-years tall, and the whole structure may be only a few million years old. Within the bubbles, extremely energetic electrons are interacting with lower-energy light to create gamma-rays, but right now, no one knows the source of these electrons.
Are the bubbles remnants of a massive burst of star formation? Are they leftovers from an eruption by the supermassive black hole at our galaxy's center? Or did these forces work in tandem to produce them? Scientists aren't sure yet, but the more they learn about this amazing structure, the better we'll understand the Milky Way.