Last week we mentioned the release of the hard-science fiction Diamonds In The Sky online anthology, edited by Mike Brotherton. Science Not Fiction is going to be looking at some of the individual stories over the next few weeks, and we decided to kick off with one co-written by our old pal, Kevin Grazier and Ges Seger. Because the story, Planet Killer, is a cosmic whodunnit, we'll leave our discussion below the jump: come back when you've read it! The core point of Planet Killer is that there natural things out in space that are a lot more dangerous than any invading fleet of aliens you could care to mention. (The Bad Astronomer, Phil Plait, has written an excellent book on this whole notion with the subtly-titled Death From The Skies: These Are The Ways The World Will End, which Kevin mentions in his commentary at the end of the story.) The kind of cosmic event that can make for incrediblybeautiful Hubble Space Telescope pictures, can also spell death for anyone who happens to be close by. Unfortunately for us, in the case of a Gamma-ray burst of the sort that is at the heart of the mystery of Planet Killer (I told you to read the story first!), being close by can mean "in the same galaxy." Gamma-ray bursts are believed to be produced by stars getting swallowed up be a black hole or the merger of two super-dense neutron stars. In either case, the result is two beams of intense radiation shooting away from the triggering event like beams from a lighthouse. Each beam is big enough and powerful enough to fry any solar systems that happen to have the misfortune of sitting in its path, even if the Gamma-ray burst originates on the other side of the galaxy. Much is unknown about these bursts and how they are produced. But although unpredictable, Gamma-ray bursters are bright enough to be seen at intergalactic distances, and there are enough galaxies visible in the sky to make keeping an eye out for them worthwhile. In the past, the difficulty has been coordinating observations, so that the detection of gamma rays can be correlated with other types of radiation, such as light, allowing us to pin down the precise origin of such bursts. Fortunately, orbiting satellites like the recently launched Fermi Gamma-ray Space Telescope have made this task much easier. Just last month, the Fermi detected the most powerful Gamma-ray burst ever—fortunately one which occurred a comforting 12.1 billion light years away.