Travelling at a speed of 37,000 miles per hour, the Voyager I spaceprobe is now 35 years into its mission and 11.4 billion miles from home. In the past few months, scientists have seen changes that suggest the probe is at long last leaving our solar system and soon will discover what lies in between the stars. Scientists refer to the regions between stars as interstellar space.
Voyager 1 entered the outermost part of the solar system, referred to as the heliosheath, in 2004. In 2010, Voyager I entered the outer most part of the heliosheath which is referred to as the heliopause. Soon, Voyager will leave its solar system behind and begin a 38,260 year journey to come within 1.7 light years of an obscure star in the constellation Ursa Minor (the Little Bear or Little Dipper) called AC+79 3888.
When the probe entered the heliopause it discovered strange magnetic field bubbles produced by the spin of the sun. The above video from June, 2011 illustrates the strange bubbling effects and explains how scientists figured out what they were. In the heliopause, the solar wind pressures balance so the solar wind has all but disappeared for Voyager. However, there’s been a 100-fold increase in the intensity of high-energy electrons from elsewhere in the galaxy. The electrons are diffusing into our solar system through the heliopause’s magnetic bubbles.
For many years, scientists believed there existed a region of our solar system beyond the heliopause, referred to as the “Bow Shock” where forces outside the solar system struck the magnetic fields of the heliopause. Using data from the Voyager probes and IBEX, scientists learned that the bow shock doesn’t exist because the heliosphere isn’t moving fast enough to create a shock.
Six months ago a study was published that used data from the Cassini and Voyager space probes to estimate the size of the solar system. Scientists learned that our solar system is smaller than they believed. Scientists realized the Voyager could leave our solar system at any time.
Last month, scientists found further evidence that Voyager has begun to leave our solar system. Rapid increases in the number of outside solar particles suggest Voyager is approaching interstellar space. Still scientists admit, they can’t be certain until the magnetic bubbles dissipate.
According to computer models, the bubbles are large, about 100 million miles wide, so it takes the Voyager probe months to cross just one of them.
Nov 15, 2012 by Todd Miller, Ph.D.