The probe's plasma wave instrument recently returned data showing a marked increase in the plasma density, the same jump Voyager 1 experienced when it escaped the influence of the solar winds and entered the interstellar medium, or ISM. Two spacecrafts had different paths: Voyager 2 didn't rush to the edge of Solar System, it explored Uranus and Neptune during planetary flybys first. A year ago, the mission checked off yet another achievement when Voyager 2 followed its twin through the bubble that surrounds our solar system.
The NASA probe has sent back data of what is out there beyond, beyond the solar system's edge.
Voyager 2's entry into the ISM occurred at 119.7 astronomical units (AU), or more than 11 billion miles from the Sun.
Among many things, the astronomers are looking to gain a better understanding of how the solar winds - the stream of charge particles coming out of the sun - interact with the interstellar winds, made up of particles from other stars.
Scientists estimated that Voyager 2 left the solar system late past year, but the latest findings - published this week in the journal Nature - offer confirmation.More news: Coronavirus deaths in Italy over 4000
"This is very odd", said Tom Krimigis, a scientist in the Applied Physics Laboratory at Johns Hopkins University and senior author of a study reporting on measurements of charged particles. We had no quantitative idea of how big this bubble is that the sun creates around itself with its supersonic solar wind, made of ionized plasma, which is speeding away from the sun in all directions. The density is similar to the plasma densities inferred by Voyager 1's scientists, with small discrepancies likely due to their differences in location.
The boundary between the two regions is known as the heliopause. The presence of the outer layer came to light after Voyager 2 crossed the interstellar space.
"The two Voyagers will outlast Earth", said Dr. Bill Kurth, a research scientist at the University of Iowa. Voyager 2 traveled from the hot, lower-density plasma of the heliosphere to the cold, higher-density plasma of interstellar space.
"But contrary to all expectations and predictions, the magnetic field direction did not change when Voyager 2 crossed the heliopause", Leonard Burlaga, a scientist at the NASA Goddard Space Flight Center and lead researcher for one of the studies, told AFP.
"Think of a cold front that forms when a very cold air mass comes down to the US from Canada", said Don Gurnett, professor of physics at the University of Iowa. This was consistent with the fact that the two probes encountered the heliopause at different distances from the Sun. "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".
After 42 years in action, they are still going strong, although both will run out of power and fall silent within five years. "Once we left the heliosphere, we continued to see particles leaking from the inside out". Ultimately, measurements of the behaviour of local electrons and magnetic fields confirmed that it had crossed the boundary.More news: High number of players want to join Brady in Tampa Bay
Shaped something like a windsock in a stiff breeze, the heliosphere is formed by the Sun's magnetic field and solar winds that can reach speeds of three million kilometres per hour.
The approximate positions of Voyager 1 and 2.
It will be some time before we have more data to study.
Its companion, V1, the only other human-made spacecraft to have ventured as far, passed over into interstellar space six years earlier in 2012 at a distance of 121.6 au (18.3 × 109 km).
The last measurement obtained from Voyager 1 was when the spacecraft was at 146 AU, or more than 13.5 billion miles from the sun. Supernovae send shock waves out into the galaxy as well, stirring the interstellar medium, albeit at a much more intense scale than CMEs.
"Voyager 2's interstellar arrival is a significant milestone because we are now able to look at our own star from outside in rather than inside out, and from not just one, but two perspectives", Rankin said. The space between stars also contains cosmic rays.More news: Regeneron COVID-19 Drugs Ready For Human Trials Early This Summer