(1) The heliopause was expected to be a rather sharp boundary between the sun's domain and interstellar space.

(2) It's now 17 billion kilometers from Earth. And it should be close to the heliopause, where the plasma flowing outward from the sun no longer holds back the interstellar winds.

(3) Or it could mean that Voyager 1 has already crossed the heliopause. Either way, the spacecraft becomes the first object in interstellar space created by intelligent life. That we know about.

(4) Still operational, both Voyagers are headed towards the outer boundary of the solar system, in search of the heliopause and the beginning of interstellar space.

(5) After 34 years in space, 17 billion miles from Earth, Voyager 1 has reached or is about to reach the heliopause.

(6) Many astronomers think that the limit of the heliosphere, known as the heliopause, is about 9 billion miles (15 billion kilometers) from the sun.

(7) Beyond the orbit of Neptune one finds the disk-shaped Kuiper belt, in which dwarf planet Pluto resides, and far beyond that is the giant, spherical Oort Cloud and the teardrop-shaped heliopause.

(8) That could mean that Voyager 1 is drawing close to the heliopause, which just happens to be surrounded by a broad expanse of calm.