In my blog on June 18, planetary scientist Alan Stern commented on the recent reclassification of Pluto and other outer solar system bodies as “plutoids” instead of planets. We’ve been talking again, this time in response to a conference, "Great Planet Debate: Science as a Process," at the Johns Hopkins Applied Physics Laboratory in Baltimore August 12. It was a chance for scientists to discuss the issues underlying what is being called...

Yesterday, I participated in a press teleconference announcing new observations and research on the brightest bang ever seen in the sky. Astronomers on Earth saw it March 19, 2008, but it actually happened 7.5 billion years ago when a massive star collapsed and formed a black hole, producing an event astronomers call a gamma-ray burst. For about 40 seconds, its optical flash was visible to the naked eye. You’ll see lots of coverage of this in the...