National Geographic News
An illustration of the Voyager spacecraft.

This artist's concept shows the general locations of NASA's two Voyager spacecraft.

Illustration courtesy Caltech/NASA

Dan Vergano

National Geographic

Published September 12, 2013

It’s official: Voyager 1 has slipped from the solar system.

Launched in 1977, Voyager 1 traveled past Jupiter and Saturn and is now more than 11.66 billion miles (18.67 billion kilometers) from the sun, becoming the first spacecraft to enter interstellar space. Proof of this long-anticipated milestone for the storied spacecraft comes in a study released Thursday by the journal Science and announced at a celebratory NASA headquarters briefing.

"We made it! We are in interstellar space," said Voyager scientist Ed Stone of the California Institute of Technology in Pasadena, speaking at the briefing.

Solar storm aftershocks at the edge of the solar system provide confirmation that the Voyager 1 spacecraft made the passage on August 25, 2012, space agency scientists said Thursday.

On that date, Voyager 1 passed beyond the fringes of the sun's outward-flowing solar wind and into the interstellar space between the stars.

"It is an incredible event, to send the first human object into interstellar space," says study lead author Donald Gurnett of the University of Iowa in Iowa City. "It’s not quite the moon landing, but we are where the solar wind ends."

Finding the Solar System’s Edge

The solar wind flows outward from the sun traveling at one million miles (1.6 million kilometers) an hour, a bath of energetic particles that's blasted off the solar surface and into space, where it surrounds our star like a bubble.

At its edges, the solar wind piles up into the "interstellar wind," a cloud of cooler charged particles that suffuse the thin vacuum of space between stars. Since 2004, Voyager 1 had been traveling within the boundary region between the solar wind and the interstellar wind, which is the cooked-off debris of thousands of exploded stars in our Milky Way galaxy.

Knowing exactly where the solar wind ends and where interstellar space begins has been an open question among space scientists for more than four decades, says Stone.

Since an instrument for directly detecting that transition died in 1980, the researchers have had to rely on indirect measures of magnetic and electrical activity from other instruments aboard Voyager 1 to find an answer.

One key to identifying this boundary is the difference in the density of charged particles between the solar wind and interstellar space, as it is about 50 times greater in the latter region.

Looking at a pair of solar storms that caught up to the spacecraft last October and then again last April, Gurnett’s team reported that measured changes in electrical activity around Voyager correspond to interstellar space.

As the storms passed the spacecraft, they triggered spikes in electrical and radio waves that uniquely corresponded in frequency to the spacecraft having entered the more densely charged interstellar space.

Based on that increase, the team extrapolated the entry date for Voyager 1 into interstellar space as August 25, 2012.

"The spacecraft doesn't feel anything traveling into interstellar space. We can only detect the transition because of its instruments," says Stone, who was not on the study team.

The new report confirms an analysis made last year that found that Voyager had entered interstellar space, based on indirect measurements.

Stone finds the new report convincing: "Nature has finally given us a nice set of solar storms which show us that Voyager is now out in interstellar space."

Surprise! Galaxy, Sun's Magnetic Fields Aligned

Scientists were surprised by NASA's finding that the galaxy's magnetic field is apparently aligned in the same direction as the sun's, forming a "magnetic highway." Space scientists had generally assumed that the galaxy's magnetic field would have some other direction.

The alignment had stymied attempts to use magnetic measurements to determine a starting line for interstellar space.

"We have a lot to learn still, I think, is what it means," says Voyager scientist Stamatios Krimigis of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, who reported the magnetic highway results last year.

Along with Voyager 1's measurement of increased galactic cosmic rays (the solar wind serves to partly shield the solar system from these high-powered rays), the new results have Krimigis "absolutely convinced."

"In the same way that Sputnik carried us out of the Earth's atmosphere in 1957, Voyager has now carried us outside the sun's atmosphere," Krimigis says. "It is quite an achievement in the short time that we have had spaceflight."

Given the estimated lifetime of the plutonium battery aboard Voyager 1, its last signals should be heard on Earth around 2025, Stone says. The spacecraft will eventually pass within 1.7 light years (about 16.1 trillion kilometers) of another star in 40,000 years, according to Voyager project manager Suzanne Dodd of NASA's Jet Propulsion Laboratory in Pasadena, California.

The spacecraft's twin, Voyager 2, which explored Jupiter, Saturn, Uranus, and Neptune, is also still kicking, now some 9.55 billion miles (15.36 billion kilometers) from the sun on its own journey.

"It has really been an exciting 40 years for the mission, and the next 10 years should be exciting ones as well," Stone says. "We are still exploring places we have never been."

57 comments
Daniel Furtado
Daniel Furtado

What's the speed of the spacecraft? My math indicates a speed around 57.133 km/h = 15.870 m/s, someone know if that's the correct speed?

Normand Chouinard
Normand Chouinard

Amazing little machine operating so far away from where it was created, facing such extreme conditions and travelling at such a speed. Hope it ends its days in a museum on a like planet somewhere in the universe  as a...UFO from unknown origins.

HELIE André
HELIE André

Je crois que la seule raison valable de devenir immortel  est d etre encore là dans quelques millions d années pour enfin ,peut etre ?,savoir que recele notre univers dans son extreme dimension,explorer le bout de quoi ?  mettre un terme à ce vertige qui nous prend si on laisse flotter notre esprit audelà de l audelà.....

Jimbo Manomanomano
Jimbo Manomanomano

 I predict in a couple of years it will send back a photo......being bombed by some Alien with a sense of humor.

Or....It will just hit a wall, and we'll all realize we are the stars of a  reality show for some race of supreme beings

Chander Kumar Bhagirath
Chander Kumar Bhagirath

It is indeed a great information which is really putting us in that interstellar space as well.

Hats off to the recent research. 

Isac Santhakumar
Isac Santhakumar

Really a wonderful article.It has taken me to an un known place.Was it a dream land?

Rob Tek
Rob Tek

And in a few hundred years  VGER will come back and destroy us all, or

Preston Ford
Preston Ford

Amazing. This is why I love science. Always something new!!

Asogan Jayaraman
Asogan Jayaraman

I HOPE VOYAGER WILL STILL BE ABLE TO TRANSMIT PICTURES OF SPACE OUTSIDE OUR SOLAR SYSTEM.THANKS TO NASA 

Mitra R. Ramkissoon
Mitra R. Ramkissoon

This is an amazing article. I hope that one day, when space travel is streamlined, we would be able to retrieve Voyager 1 after its batter gives out. It will be a monumental piece of history which testifies to the ingenuity of mankind. 

Laurin Dykstra
Laurin Dykstra

I so wish that men would stop wars and pay attention to space. If everyone worked together we would already have an exploring vehicle out there and I bet we would be send things on phenomenal speeds!  But alas, we must first deal with man learning to live together with different religions, (i would say cultures but we have overcame many of those already)  Sometimes I think we are achieving soo much, and other ways we are as primitive as apes. 

Peace everyone :)

Nick Hill
Nick Hill

Thats amazing. And to think how much more space it has left to explore...

Christopher LePage-Dubé
Christopher LePage-Dubé

Truly amazing. It is a pity that there are people out there who cannot even comprehend the Earth-Moon distance let alone the Voyager 1-Earth distance trying to belittle the accomplishment.

Ricardo Ramos
Ricardo Ramos

Amazing!!! I´m following it since its lauch,and now its free from our Sun...what a journey

Yosef Haile
Yosef Haile

It's incredible! ...human made object might be considered as "UFO" in the unknown space farther away there...Great job, Stone!

Wei Yiming
Wei Yiming

Well, that's definitely incredible, although the journey ahead of Voyager 1 is still long to be recovered, this trip will be full of wonders and amazing dicoveries!

Jonathon A.
Jonathon A.

The escape of Voyager 1 from our solar system definitely marks a milestone not only for space exploration, but also the world as a whole. Most we know of what’s beyond our own miniscule planet is speculation. Voyager is a product of mankind that has exceeded the boundaries of our solar system. The craft has taught us so much of our own solar system, and now we are learning of what lies beyond. The success of penetrating the magnetic barrier of the sun is the first step of truly understanding our galaxy by probe.

The Voyager 1 spacecraft has travelled 11.6 billion miles from the sun, and is still going. Scientists calculated from a solar storm that the craft had entered interstellar space, by calculating the frequency of electricity it had intercepted at that time. Scientists have also determined from Voyager that the Galaxy shares a magnetic field our sun. This finding has given us a general understanding of which way is up in our solar system.

Imagine the Milky Way galaxy as a book. Our solar system is merely a sentence. Voyager is mankind’s attempt to see what the next chapter holds. Perhaps one day the spacecraft will venture into an unknown solar system and be greeted by new, revolutional findings for us here on Earth: unveiling a new paragraph for us to read about. 

james jack
james jack

We could do so much more than this....if there was intrest :-(  

Lawrence Sonders
Lawrence Sonders

Awesome !!  11.7 Billion miles !!!  I still can't   really get my mind to fully realize that when watching a glorious sunset from my deck on Fire Island that I am looking at a sun   93 million miles distant with unaided eyes !!

Thanks for this article.

Sciencegroup Ofindia
Sciencegroup Ofindia

Subject: NASA is BLUFFING that Vigour 1 has left SOLAR SYSTEM,

NASA is BLUFFING that Voyager 1 has left SOLAR SYSTEM,Oort cloud http://en.wikipedia.org/wiki/Oort_cloud that may lies roughly 50,000 AU, or nearly a light-year, from the Sun50000 au = 50000 x (15 0000000 ) = 7,500 000 000 000 =7.5Trillion km from sun Presently the Voyager 1 is just a 17Hour light distance ONLY (JUST 1/500th distance from the Oort cloud – limit to the Solar System) at about 12 Billion miles ONLY and Not in the interstellar space at the Edge. Earth speed is 40 Km /s =40x3600=144000 /h But still cannot leave gravitation of Solar system!Oort cloud is just a standstill but still has speed of about ½ CM /s at the edge of solar system Nothing can leave the Sun and cannot go in the interstellar space as SOLAR system gravitation does not allow anything go beyond the limit to go away in the interstellar space at

Jeff Moreau
Jeff Moreau

How does NASA know it won't collide with something during 20,000 yrs?!

Christopher LePage-Dubé
Christopher LePage-Dubé

Basically public interest in the Space program has waned since the Moon landings. Today nobody really cares to the point where basic space information is being incorrectly reported by the media. Too lazy to do any research is the thing of today.

Furthermore every new administration that comes along has been chopping NASA's budget for years now. That is why there has been no quality space missions in more than a generation.

Mark Sr.
Mark Sr.

How come with our advancement in technology since 1977 with aerospace, computers, cameras, communication, self sustaining power and the greater knowledge we now have of space exploration. Why haven't we built a new and better voyager space exploration craft that can actually travel to other star systems? Why are we putting off going to Mars for 20 plus years ? Why are we slowly closing down NASA and allowing private companies to take over our space programs. We just upped and stopped going to the moon with no real explanation as to why. With one president telling us we were going back and another shutting it down. Imagine our technology now being where voyager 1 is...Instead we have a toaster up there that really isn't teaching or showing us nothing and will fade out and stop working in a few years...I admit it is a big feat for those in 1977 but this is 2013....Time for a new Voyager to be sent out in the cosmos !!!!

David Day
David Day

Voyager 1 and 2, just keep going and surprise us more!!!!   

David Gonzalez
David Gonzalez

This is a testament to us to see what we can do. Now if we can just stop bickering with eachother...

Dylan Baker
Dylan Baker

Question how do we stay in contact with the voyager?

Flygon Zhang
Flygon Zhang

@Mitra Ramkissoon Hold your horses there, by the time we have a reliable space traveling network set up the Voyagers' are going to be lightyears away, we'll have no contact with them, and we'll have no idea how to find it again. Also, as there's no atmospherical resistance in interstellar space, the Voyagers are going to keep going forever unless they hit something and destroyed, with or without power.

Flygon Zhang
Flygon Zhang

@Mark Sr. And they're afraid something's going to go wrong and that if something does go wrong the public will turn its back on them.

Rosie Harper
Rosie Harper

@Mark Sr. it costed a lot to go to the moon. it'd cost a ton more now to go to mars.

Eric Paul
Eric Paul

@Mark Sr. Because religious nuts, that still run most countries (including the US) don't believe there's any point to space exploration.  On top of it, most people would rather spend all of our money trying to balance our inflated population than to advance science!

Dan Vergano
Dan Vergano

@Dylan Baker NASA's Deep Space Network communicates daily with the 22 watt transmitter aboard the spacecraft, messages that take more than 17 hours to reach Earth. Every six months they do a full data dump from the spacecraft's recorder.

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