All known black holes fall into two categories: small, stellar-mass black holes weighing a few suns, and supermassive black holes weighing millions or billions of suns. Astronomers expect that intermediate-mass black holes weighing 100 — 10,000 suns also exist, but so far no conclusive proof of such middleweights has been found. Today, astronomers are announcing new evidence that an intermediate-mass black hole (IMBH) weighing 2,200 suns is hiding at the center of the globular star cluster 47 Tucanae.