Scientists have decoded the signals sent by NASA’s Voyager 2 from about 11 billion miles away from interstellar space, which will help scientists paint a clearer picture of cosmic shoreline, where the heliosphere ends and interstellar space begins. The findings of when Voyager 2 crossed the heliosphere and entered interstellar space a year ago, have been published in five new research papers in the journal Nature Astronomy.
Each paper has been dedicated to one of the five operating science instruments onboard Voyager 2. These include magnetic field sensor, two instruments to detect energetic particles in different energy ranges and two instruments for studying plasma, which is a gas composed of charged particles.
“The Voyager probes are showing us how our Sun interacts with the stuff that fills most of the space between stars in the Milky Way galaxy,” said Ed Stone, project scientist for Voyager and a professor of physics at California Institute of Technology (via NASA). “Without this new data from Voyager 2, we wouldn’t know if what we were seeing with Voyager 1 was characteristic of the entire heliosphere or specific just to the location and time when it crossed,” Stone added.
Among other things that were confirmed by the two Voyager spacecraft was that the plasma inside the heliosphere is significantly less dense and less cold than the plasma in local interstellar space. Voyager 2 also sent out signals that hint that the plasma outside the heliosphere could be compressed as it is slightly warmer, though it is unclear what is causing the compression.
The heliosphere is somewhat leaky, revealed Voyager’s particle instruments. Another surprising revelation was the magnetic field in the region just beyond the heliopause is parallel to the magnetic field inside the heliosphere. This was more clearly confirmed by Voyager 2 spacecraft. The edge of the heliosphere is called the heliopause.