Despite reports to the contrary, NASA’s tiny interplanetary probe Voyager 1 has not really left the solar system yet. 
 
 Launched more than 35 years ago, Voyager 1 is the most distant man-made object from Earth. After making an incredible tour of the outer planets of our solar system, the probe was directed on a course away from the sun and is now more than 18 billion kilometers from our world. 
 
 A study released Mar. 20 suggests that the spacecraft has entered a new region, where the charged-particle wind emitted by the sun no longer dominates, and will soon venture into interstellar space. Some have taken this to mean that Voyager has exited the solar system. Unfortunately, many researchers, including the probe’s own science team, disagree. 
 
 “It is the consensus of the Voyager science team that Voyager 1 has not yet left the solar system or reached interstellar space,” wrote astronomer Ed Stone of Caltech, the mission’s project scientist, in a NASA statement. 
 
 It is actually a very difficult problem identifying exactly where the solar system ends and interstellar space begins. The sun’s particle wind is thought to recede in strength as one ventures farther and farther away, eventually declining to nothing. At this point, there should be a sharp drop in the temperature of charged particles and an increase in galactic cosmic rays, which dominate interstellar space. But scientists have little information about what exactly happens at this distance from the sun. Voyager 1 is a pioneer in this region. 
 
 Voyager 1′s instruments have detected a drop in radiation levels and a spike in cosmic rays. Whether or not this means the probe is outside the solar system or simply in a new, previously undiscovered area remains to be seen. 
 
 People should be skeptical of claims of Voyager 1 exiting the solar system as NASA has sung this tune several times before. In October, the exact same headlines announced the spacecraft’s farewell and were soon thereafter contradicted with further data. The definition of where the solar system ends ultimately comes down to semantics. The sun’s radiation may no longer be affecting the probe but its gravitational influence extends for many more billions of miles. The Oort cloud, a hypothetical band of icy rocks thought to lie 7.5 trillion km from the sun, should still be gravitationally bound to our local star and could therefore be considered the edge of the solar system. Voyager 1 has a long way to go before it reaches that distance. ||||| NASA's Voyager 1 spacecraft has entered a new region between our solar system and interstellar space, which scientists are calling the stagnation region. This image shows that the inner edge of the stagnation region is located about 10.5 billion miles (16.9 billion kilometers) from the sun. The distance to the outer edge is unknown. 
 
 NASA's Voyager 1 spacecraft — the farthest-flung object created by human hands — has traveled beyond the sun's sphere of influence and may even have left the solar system forever, a new study suggests. 
 
 On Aug. 25, 2012, 35 years after the Voyager 1 mission launched, Earth's most distant spacecraft detected a sharp change in the intensity of fast-moving charged particles called cosmic rays, suggesting it had left the outermost reaches of the heliosphere marking the edge of the solar system. 
 
 "Within just a few days, the heliospheric intensity of trapped radiation decreased, and the cosmic ray intensity went up as you would expect if it exited the heliosphere," said Bill Webber, professor emeritus of astronomy at New Mexico State University in Las Cruces, in a statement. 
 
 The scientists still don't know for sure, however, whether the probe has entered interstellar space or if it remains in a mysterious in-between region Voyager team members first discovered a few months ago. 
 
 "It's outside the normal heliosphere, I would say that," Webber said. "We're in a new region. And everything we're measuring is different and exciting." 
 
 Voyager chief scientist Ed Stone said most mission researchers don't believe the spacecraft has popped free into interstellar space just yet. 
 
 "It is the consensus of the Voyager science team that Voyager 1 has not yet left the solar system or reached interstellar space," Stone, a physicist at Caltech in Pasadena, said in a statement. "In December 2012, the Voyager science team reported that Voyager 1 is within a new region called ‘the magnetic highway’ where energetic particles changed dramatically. A change in the direction of the magnetic field is the last critical indicator of reaching interstellar space, and that change of direction has not yet been observed." 
 
 Webber and his colleagues noticed the dramatic cosmic ray signal drop when Voyager 1 was about 11 billion miles (17.7 billion kilometers) from the sun. Anomalous cosmic rays trapped in the heliosphere's outer reaches dropped to 1 percent of their previous level. Meanwhile, galactic cosmic rays, which come from outside the solar system, jumped to twice their previous levels, reaching their highest levels since the spacecraft launched, researchers said. 
 
 The findings have been accepted for publication in the journal Geophysical Research Letters. 
 
 Voyager 1 was actually the second of NASA's two Voyager spacecraft to launch on historic tours of the solar system. Voyager 2 blasted off on Aug. 20, 1977, with Voyager 1 following a few weeks later on Sept. 5 of that year. 
 
 Both spacecraft carry a gold-plated copper disc containing sounds and images of Earth. The golden record is about 12 inches (30 centimeters) across and attached to the hull of each Voyager probe. The records are engraved with a diagram that explains how to play them and where Earth can be found, just in case the Voyager probes are discovered by intelligent extraterrestrial lifeforms. 
 
 Editor's Note: This story was updated at 2:40 p.m. EDT to better reflect scientists' uncertainty about whether or not Voyager 1 has left the solar system, and to add thoughts from Voyager mission chief scientist Ed Stone. 
 
 Follow Tia Ghose on Twitter @tiaghose. Follow us @Spacedotcom, Facebook or Google+. Original article on SPACE.com. ||||| NASA Voyager 1 and 2 have been in space for 33 years and have traveled 11.5 billion and 9.5 billion miles respectively. 
 
 Updated 1:51 p.m. 
 
 It was a threshold crossed in the deepest reaches of space: A spacecraft launched from Earth has now entered new and unexplored territory that may or may not be outside our solar system. A press release issued at 11:05 a.m. Wednesday morning by the American Geophysical Union noted that Voyager I had exited our solar system, sparking excitement in the scientific community. 
 
 But just a few hours later, the AGU stood down from its initial announcement that the 35-year-old craft had exited the solar system and instead clarified its location. The substance of the findings that precipitated the announcement remains the same, but the headline of the release has been changed, according to an e-mail the AGU sent out at 1:28 p.m.: 
 
 CORRECTED — Voyager 1 has entered a new region of space, sudden changes in cosmic rays indicate 
 
 NASA, which quickly denied the original report, sees nothing wrong with AGU’s science, merely how it phrased its findings. “The headline on the press release seemed to go beyond the study,” said Veronica MacGregor, spokeswoman for NASA’s Jet Propulsion Laboratory (JPL). But not all that far beyond: Voyager 1 has been at the frontier of the solar system for a long time, and unlike borders on the Earth—which are clearly drawn and, even in terms of sea and sky, have firmly fixed airspace and coastal limits—the official edge of the solar system is a mystery. NASA and the AGU agree that two recent discoveries about changes in the charged particles surrounding Voyager 1 put it at the very doorstep of interstellar space. JPL scientists are waiting for a third indicator, regarding the direction of magnetic lines, before they will officially announce that Elvis has indeed left the building. Said JPL in a statement released at 2:01 p.m. ET. 
 
 “The Voyager team is aware of reports today that NASA’s Voyager 1 has left the solar system,” said Edward Stone, Voyager project scientist based at the California Institute of Technology, Pasadena, Calif. “It is the consensus of the Voyager science team that Voyager 1 has not yet left the solar system or reached interstellar space. In December 2012, the Voyager science team reported that Voyager 1 is within a new region called ‘the magnetic highway’ where energetic particles changed dramatically. A change in the direction of the magnetic field is the last critical indicator of reaching interstellar space and that change of direction has not yet been observed.” 
 
 What’s not in dispute among any of the scientists is that the spacecraft is now, undeniably, in a new and unexplored region—pushing the reach of humanity farther than it’s ever gone before. What we call that place is, in many respects, less important than the fact that we’re there at all. 
 
 Updates 1:15 PM 
 
 According to new scientific findings set for publication in the journal Geophysical Research Letters, Voyager I has pushed into the great unknown. 
 
 NASA, however, remains skeptical about these new conclusions. “Consensus of the mission team is that NASA’s Voyager spacecraft has not left the solar system,” a NASA social media specialist told TIME via e-mail. “Statement soon from NASA Jet Propulsion Laboratory.” 
 
 (PHOTOS: Voyager, 11 Billion Miles Later: Photos from the Depths of our Solar System) 
 
 For years, scientists have speculated as to when Voyager would finally leave all traces of our sun behind — officially exiting the heliosphere, and entering the great undiscovered country beyond. 
 
 Two years ago, when TIME’s own Jeff Kluger penned his Voyager appreciation (34 years, still flying on — and on, and on), he reflected on the astonishing journey that the craft had taken — and the awesome boundary that lurked ahead: “There’s no way of knowing exactly where the solar system ends, but the best guess is that it’s up to 14 billion miles (23 billion km) from the sun,” Kluger wrote. “That’s where the last breaths of solar wind — the storm of charged particles the sun pours out all the time — bump up against the tenuous hydrogen and helium that swirl through the cosmos. Fourteen billion miles is about three times the maximum distance of Pluto (which was still a planet when the Voyagers were launched), so scientists always knew there would be a lot of flying to do before the ships crossed that threshold. That endgame, however, is approaching. Voyager 1 is currently about 11 billion miles (18 billion km) away; Voyager 2 trails a bit at 9 billion miles (14 billion km). In December of last year, Voyager 1 beamed back data showing that the charged particles around it appeared to have come to a standstill, suggesting that it had entered a final transition zone before interstellar space…” 
 
 Wednesday morning, word came down from one group of researchers that interstellar space had now been reached. Their initial findings were laid out in the form of a press release from the American Geophysical Union: 
 
 Thirty-five years after its launch, Voyager 1 appears to have travelled beyond the influence of the Sun and exited the heliosphere, according to a new study appearing online today. The heliosphere is a region of space dominated by the Sun and its wind of energetic particles, and which is thought to be enclosed, bubble-like, in the surrounding interstellar medium of gas and dust that pervades the Milky Way galaxy. On August 25, 2012, NASA’s Voyager 1 spacecraft measured drastic changes in radiation levels, more than 11 billion miles from the Sun. Anomalous cosmic rays, which are cosmic rays trapped in the outer heliosphere, all but vanished, dropping to less than 1 percent of previous amounts. At the same time, galactic cosmic rays – cosmic radiation from outside of the solar system – spiked to levels not seen since Voyager’s launch, with intensities as much as twice previous levels. The findings have been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union. “Within just a few days, the heliospheric intensity of trapped radiation decreased, and the cosmic ray intensity went up as you would expect if it exited the heliosphere,” said Bill Webber, professor emeritus of astronomy at New Mexico State University in Las Cruces. He calls this transition boundary the “heliocliff.” In the GRL article, the authors state: “It appears that [Voyager 1] has exited the main solar modulation region, revealing [hydrogen] and [helium] spectra characteristic of those to be expected in the local interstellar medium.” However, Webber notes, scientists are continuing to debate whether Voyager 1 has reached interstellar space or entered a separate, undefined region beyond the solar system. “It’s outside the normal heliosphere, I would say that,” Webber said. “We’re in a new region. And everything we’re measuring is different and exciting.” The work was funded by NASA’s Jet Propulsion Laboratory in Pasadena, Calif. 
 
 (PHOTOS: Window on Infinity: The Month in Space) 
 
 The original article has been updated to include an initial response from NASA.
– Space fans will have to hold off on popping the champagne cork. After the American Geophysical Union declared this morning that Voyager 1 had achieved the mind-boggling feat of leaving our solar system, NASA threw a wet blanket on the party, at least temporarily, reports Time. “It is the consensus of the Voyager science team that Voyager 1 has not yet left the solar system or reached interstellar space," says project scientist Edward Stone. The AGU later toned down its press release. The spacecraft, launched in 1977, is at the very least close to the edge of the solar system, but NASA says it needs more data, specifically the detection of a "change in the direction of the magnetic field," to declare Voyager the first interstellar traveler, reports Space.com. The fact that it's in such new territory is what makes verification tricky. "It is actually a very difficult problem identifying exactly where the solar system ends and interstellar space begins," writes Adam Mann at Wired.