I read this book in my school's library and that was a long time ago. I will give my best to reproduce the important parts of it. Few scientists, while working on something in Antarctica observe that the sun goes dark for a very minute fraction of a second. One of the scientists recalls that this happened before and they investigate on that. Later they observe through some telescopic images that an alien space ship was draining energy from sun which caused that small moment of darkness.They then go near the sun and try to stop the aliens and save the human race. I also remember the last scene. The scientist's daughter watches the beautiful sun rising the next morning.