The Milky Way was the name of the galaxy that contained the Solar System. It contained more than one hundred and thirty billion stars and a large number of star clusters, nebulae, and various types of interstellar gas and interstellar dust.
It had a diameter of more than one hundred thousand light-years. The thickness of it at its center was about twelve thousand light-years, and its total mass was one hundred and forty billion times the mass of the sun.
Earth was as tiny as a speck of dust in the starry skies of this vast universe.
In the vast Milky Way, humans had always felt lonely despite the hundreds of millions of stars. That was because human beings had never found their own kind in the universe. After all, the universe was simply too big.
At this time, human beings, who had always thought that they were alone in the universe, finally discovered a similar life form—although these life forms did not seem to be very friendly…
