Black hole surprises
Figure 1. An artist’s drawing of a black hole named Cygnus X-1. It formed when a large star caved in. This black hole pulls matter from a blue star beside it. Credits: NASA/CXC/M.Weiss
What are black holes?Black holes are formed when a star dies. But it must be a heavy star, 5-10 times heavier than … More “Black hole surprises”
A cosmic mystery, Part 2: Quasars.
TWO COSMIC MYSTERIES. I have personally encountered two cosmic mysteries early in my career – like about 40 years ago. They both involved massive, unprecedented sources of energy. The mysteries continued for decades and occasionally the two encounters kept popping up in my memory. Only in the last few years have both these mysteries been … More “A cosmic mystery, Part 2: Quasars.”