I am trying to find the title of a book I read in the 80's. It is about an alien race that attacks earth. Earth has better ships because we have been fighting among ourselves but the aliens have faster than light ships. When they realize they can't beat the humans, the aliens shoot something in to the sun that causes it to burn out or explode (I can't remember). Some humans survive. One group goes to the home aliens home (disguised as an asteroid) and bomb their planet. They eventually meet up with other earth who have finally discovered the secret of faster than light speed. Does anyone know the title and author of this book?
Aliens beings from a distant space empire find earth. The first couple of attempted invasions of the solar system are beaten back. The final attack causes the sun to explode. Humanity is saved by hollowing out asteroids and making them into space warships. These asteroids disperse in different directions so that humanity will survive. The main character is given command of one of the asteroids and heads toward the supposed enemy star system. They arrive, find f-t-l information to send back to other asteroids. They then attack enemy planet to give earth survivors time to rebuild.
That book is the topic of this Goodreads discussion.