Voyager 1 has been traveling through space for quite a while -- since September 1977 -- and, according to scientists at the University of Iowa, has reached the edge of the Solar System and entered space between stars, interstellar space. Scientists confirmed this week that the NASA probe has reached and gone beyond the edge considered to be the boundary of the Solar System, the heliosphere, or the immense "bubble" to which magnetic fields and charged particles emitted by the Sun extends outward away from the star.
The Daily Mail reported July 9 that Voyager 1, a space probe which was designed for and carried out exploratory missions to the outer planets of the Solar System, had indeed become Earth's first interstellar emissary. Researchers confirmed the spacecraft had crossed into the area between stars via a trio of Coronal Mass Ejections (CMEs) from the Sun. The charged particles released in the CMEs were detected by the craft, their passage a wave that can be differentiated from the surrounding space around the probe.
Don Gurnett of the University of Iowa, Iowa City, the principal investigator of the plasma wave instrument on Voyager 1 that collected the evidence, said in a statement: "All is not quiet around Voyager. We're excited to analyze these new data. So far, we can say that it confirms we are in interstellar space."
The new data is the third Coronal Mass Ejection to be analyzed by scientists. The first two led to tentative announcements that Voyager 1 had left the Solar System in August 2012. The second was recorded in March 2013. It was during this second reading that astronomers discovered that Voyager 1 had been traveling through space 40 percent denser than before -- a strong indicator it had truly entered interstellar space.
However, definitiveness was not to be had.
A third CME, described as a solar "tsunami," detected in March provided confirmation for the diligent scientists. The plasma matter Voyager 1 was traveling through was of similar density as the second reading, indicating to investigators that the craft was actually in interstellar space, becoming the first man-made object to do so.
Professor Martin Barstow, President of the Royal Astronomical Society and Professor of Astrophysics and Space Science at the University of Leicester, explains to MailOnline the reluctance to state definitely that the spacecraft was outside the Solar System.
"It is interesting that Nasa keeps renouncing [it has entered interstellar space], but that is because it’s really hard to be sure," Barstow noted. "The boundary between the solar system and interstellar space is not very sharp, or obvious, but is complicated. It also moves as solar activity varies.
"It’s quite likely that the boundary has moved backwards and forwards past the spacecraft over the last few years as we have gone from solar minimum to solar maximum, where we are now."
Of course, some still feel that Voyager 1 is still inside the boundaries of the Solar System, according to Space.com (via Yahoo News) marking the outer limits with the massive cometary shell known as the Oort Cloud. By that standard, the NASA craft will be within the Solar System for some time to come -- anywhere from the next 14,000 to 28,000 years.
Voyager 1 will soon be joined by Voyager 2, which was actually launched two weeks prior to its twin spacecraft back in 1977, albeit sent off on a different path for its "grand tour" of the Solar System. It should hit interstellar space, or the area outside the Sun's heliosphere, in the next couple of years.