Voyager 2 Is Getting Close to Interstellar Space
It's picking up readings similar to Voyager 1 when it made the leap.
NASA is reporting
that the Voyager 2 probe, launched on August 20, 1977, has detected "an
increase in cosmic rays that originate outside our solar system." With
that data and the fact that Voyager 2 is almost 11 billion miles away
from home, scientists assume that it close to leaving the confines of
the solar system.
For the last 11 years, since 2007, Voyager 2 has
been traveling towards the outermost layer of what is known as the
heliosphere. The heliosphere is a bubble-like region of space that
encompasses not only all 8 planets, not only all 8 planets and Pluto,
but far beyond as well. The sun's solar wind—plasma—maintains this
bubble against the pressures of helium and hydrogen gasses from the
Milky Way.
The outermost layer of the
heliosphere is known as the heliopause. Beginning last August, Voyager
2's Cosmic Ray Subsystem (CRS), built to detect cosmic rays, noticed a
five percent increase in these rays hitting the probe. Speedy particles
that originate outside the solar system, they are partially blocked by
the heliosphere. The probe is currently traveling through a middle
section of the bubble known as the heliosheath. But as Voyager 2 moves
towards the heliopause, the cosmic rays it encounters will rise.
For
the first time, scientists are able to compare one object's journey
through the heliosphere's with another's. Voyager 1 crossed through this
territory years ago, in 2012, and its own CRS detected a similar rise
in cosmic rays. But scientists are quick to note that every interstellar
journey is unique, and that Voyager 2 is traveling towards a different
part of the heliopause than Voyager 1.
"We're
seeing a change in the environment around Voyager 2, there's no doubt
about that," says Voyager Project Scientist Ed Stone, based at Caltech
in Pasadena, in a press statement.
"We're going to learn a lot in the coming months, but we still don't
know when we'll reach the heliopause. We're not there yet -- that's one
thing I can say with confidence."
When Voyager 2
does hit the heliopause, it will likely experience what Voyager 1 did—a
"termination shock" that comes when solar winds collide with the
interstellar medium. And one of the greatest space programs in human history will add one more accomplishment to a very long list of firsts.
Source: NASA
The place where the speed of the solar wind becomes slower than the speed of sound is called the termination shock.
The heliosphere is the bubble-like region of space dominated by the Sun, which extends far .... The termination shock is the point in the heliosphere where the solar wind slows down to subsonic speed (relative to the Sun) because of ...
May 24, 2005 - Termination Shock:
Blowing outward billions of kilometers from the Sun is the solar wind, a
thin stream of electrically charged gas. This wind travels at an
average speed ranging from 300 to 700 kilometers per second (700,000 -
1,500,000 miles per hour) until it reaches the termination shock.
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