The Killing Star

If a species develops space ships that can cross interstellar distances in less than a lifetime, its space ships can also be used as weapons of mass destruction. And if it encounters another species with an emerging civilization, it might figure that they could develop such weapons themselves -- and decide to wipe out that civilization before it can get off the ground.

Such is the premise of The Killing Star, a hard science fiction novel written in 1995 by Charles Pellegrino and George Zebrowski.

The first hint humanity gets that spacefaring aliens exist is the detection of gamma rays consistent with Antimatter-powered engines. Our elation is short-lived, however. Almost immediately afterward, a fleet of "R-bombs" -- spacecraft accelerated to 92% of the speed of light -- slam into every inhabited planet in the Solar system, including Earth. The result is the near annihilation of the human species.

The rag-tag remnants of humanity must try to stay alive in a Solar system infested with aliens who are bent on our complete extermination.

This novel provides examples of:

 * Aliens Speaking English: The aliens don't actually have the correct vocal apparatus to reproduce human sounds. But they do have a convenient translation device which was calibrated using the next trope on the list.
 * Aliens Steal Cable: It's how our attackers find out that our civilization exists.
 * And why they considered us a threat.
 * Apocalypse How: The aliens cause an Class 4 event.
 * Artificial Intelligence:
 * Better to Die Than Be Killed:
 * Clone Jesus: And Clone Buddha! Made from, respectively, the Shroud of Turin and a tooth of the original Buddha by a doomsday cult, they and their other clone friends rebelled against the cult and went off to forge their own lives. Jesus and Buddha ultimately wind up in control of one of the last few surviving human settlements.
 * Computer Virus: The aliens send one of these to our SETI listening dish. Even with the dish unplugged from the computer network, the virus still manages to reprogram it into a Killer Robot.
 * Freeze Bomb: Humans had developed a devastating tool decades ago that transforms ambient energy into matter, leaving the surrouding area completely frozen. One group of survivors uses this to hide inside the Sun's atmosphere.
 * Grey Goo: Weaponized by the alien invaders
 * Guilt-Free Extermination War
 * Mistook the Dominant Lifeform: Two human survivors of the alien attack are abducted and have an audience with the invaders. Initially, they assume that the octopus-like creature that they're having a conversation with is one of the leaders of the invasion. In fact, it turns out that the rulers are
 * The Singularity:
 * The Singularity: