Evidence of Solar System’s Edge Found

The twin Voyager space probes have found the first evidence of the existence of the true edge of the solar system, where solar wind hits interstellar space, NASA announced Wednesday.

Although many people wrongly believe that the solar system ends with the outermost planet, scientists say its true edge is farther away from the sun at the “heliopause,” where electrically charged particles spewed by the sun collide with similar particles in interstellar space.

That collision produces intense, low-frequency radio signals that were detected by antennas on the Voyager 1 and 2 spacecraft starting in August, said University of Iowa physicist Don Gurnett, a member of the Voyager science team.

“This discovery is an exciting indication that still more discoveries and surprises lie ahead for the Voyagers as they continue their journey to the outer reaches of the solar system,” said Edward C. Stone, director of the space agency’s Jet Propulsion Laboratory.

The location of the edge of the solar system “remains one of the great unanswered questions in space physics,” although the new discovery narrows its possible location, NASA said.

The Voyager probes were launched from Florida in 1977. Both spacecraft studied Jupiter and Saturn. Voyager 2 went on to explore Uranus in 1986 and Neptune in 1989.