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NASA CONFIRMS VOYAGER 2 HAS LEFT THE SOLAR SYSTEM
NASA Confirms Voyager 2 Has Left the Solar System
Humanity first
left the solar system in 2012 when the Voyager 1 probe passed into interstellar space decades after leaving the planets behind. Now, there’s a second spacecraft beyond the limits of our solar system: Voyager 2. Luckily, Voyager 2’s instruments are in somewhat better
shape than Voyager 1’s, so scientists were able to observe the transition from
the heliosphere, which is dominated by the sun, to the interstellar medium
(ISM).
Both Voyager
probes launched in 1977, with Voyager 2 heading into space a few weeks before
Voyager 1. The two probes are physically identical, but they took different
paths through the solar system. They took advantage of the “Grand Tour,” an
alignment of the planets that occurs only once every 175 years. Voyager 1
visited and got gravity assists from Jupiter and Saturn before heading off
toward the edge of the solar system. Voyager 2 swung past Jupter, Saturn,
Neptune, and Uranus. It made its last planetary observation of Uranus in 1989,
almost a decade after Voyager 1 had started its long march toward the edge of
the solar system.
When Voyager 1
reached the edge of our solar system, known as the heliopause, it no longer had
a functional plasma spectrometer. As a result, there was some debate about
when, exactly, the probe left our solar system. So, we missed the expected
transition from warm solar plasma to the denser cold plasma of the ISM.
Eventually, measurements of local electrons and magnetic field shifts confirmed
it was in interstellar space.
Voyager 2 has
just sent back data proving that it has also crossed the heliopause, and it had
a fully functional plasma spectrometer. The transition happened about a year
ago in November 2018, and the changeover was roughly in-line with what
scientists expected based on Voyager 1’s indirect readings. As Voyager 2
crossed from the heliosphere to the ISM, it detected a 20-fold increase in
plasma density.
The approximate positions of Voyager 1 and 2.
Voyager 1 and
2 crossed the heliopause at roughly the same distance from the sun, 121.6 AU
and 119 AU, respectively. However, their exit points were about 150 AU apart.
Scientists are studying the discrepancies in the data in hopes of gaining a
better understanding of the boundary between our solar system and the wider
galaxy. For example, Voyager 2 detected a continuous change in magnetic field
directions as it crossed into the ISM, whereas Voyager 1 did not. Voyager 2 has
also continued to see low-energy particles from the sun in the ISM, but Voyager
1 didn’t.
It will be
some time before we have more data to study. The only functional probe that has
any hope of reaching the heliopause is New Horizons, which is currently flying
through the Kuiper Belt. It could leave the solar system around 2040, but we
don’t know if it will maintain communication with Earth that long.
Now read:
- NASA Just Fired Voyager 1’s Thrusters For the First Time in 37
Years
- NASA Produces Stunning Simulation of a Black Hole
- NASA
Has Fired Up the Deep Space Atomic Clock
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