Voyager Leaves the Heliosphere (More or Less)

The American Geophysical Union has come to the conclusion that the Voyager 1 spacecraft, launched from earth on September 5, 1977, has left the area of space around the Sun which is directly affected by the Sun, known as the heliosphere.

Solar radiation/wind push the heliosphere out while cosmic rays work in the opposite direction pushing the heliosphere inward.

This is a great achievement for the scientists who worked on the mission, which has been going on for decades, and for humanity in general. Not only has a machine built long ago on Earth, which is surrounded by a protective atmosphere, lasted well past its primary mission in the harsh environment of space, it is still sending back data and well on its way to another star system (though we will never know when it makes it to one).

The data from Voyager 1 seems to be pretty cut and dry. It is presented in graphical formation here:

High energy elections (red), high energy protons (black), and low energy protons (blue).

The low energy protons are given off by the Sun, while the high energy protons and electrons come from interstellar events such as supernovae  The heliosphere blocks most of these high energy particles from entering the Solar System. Thus, a large increase in the measurement of them shows Voyager 1 is beyond the influence of the heliosphere.

The paper originally published in Geophysical Research Letters can be read here.

Although Voyager is beyond the heliosphere, it is not beyond all celestial bodies which make up the Solar System. The Oort Cloud, made up of icy rock chunks, surrounds the the Sun and extends out to a distance of 50,000 astronomical units (AU), or approximately one light year. Voyager 1 will not exit the Oort Cloud for another 20,000 years, give or take a millennium.

Contact author: leucrota [at] mail [dot] com

Further reading:
Voyager: The Interstellar Mission
MIT website concerning the Heliosphere
Oort Cloud
Geophysical Research Letters - Recent Voyager 1 data indicate that on August 25, 2012 at a distance of 121.7 AU from the Sun, sudden and unprecedented intensity changes were observed in anomalous and galactic cosmic rays