'Not alike any we've ever seen before': Three of the 12 galaxies in this cosmic string are missing a crucial component of the universe

Astronomers discovered that three galaxies within a 12-galaxy cosmic string — DF2, DF4, and DF9 — are missing dark matter, the invisible substance making up 85% of the universe's matter. Scientists believe a high-speed galactic collision stripped these dwarf galaxies of dark matter, similar to the famous Bullet Cluster event. Follow-up research using a new 1,140-lens telescope in Chile may reveal further clues.