Voyager 1 enters interstellar space, bids solar system farewell!

The Voyager 1 spacecraft, launched in 1977 to study and photograph Jupiter and Saturn, has become the first man-made object to reach interstellar space. Credit: NASA

Like a young adult pushing off on her own, NASA’s Voyager 1 space probe has left the solar system for the stars beyond. At a distance of about 12 billion miles (19 billion km) from the sun, the spacecraft has become the first human-made object to travel into interstellar space – literally the space between the stars.


Amazing raw footage of Jupiter when Voyager 1 headed for the planet in Feb. 1979

Although the announcement was made today, Voyager 1 has been traveling through plasma in the space between the stars since August 2012. A plasma is a gas that’s been ionized or stripped of its electrons by energetic processes in space. The sun releases plasma in solar storms as do other stars.

Scientists on Earth knew Voyager was in a transitional region, teetering on the edge of the sun’s influence and that of the star, but not until a fortuitous storm on the sun were they certain the probe had finally crossed the border.

Illustration showing Voyager 1 near the edge of the sun’s influence called the heliosphere. Beyond the heliosphere begins interstellar space. Credit: NASA/JPL/Caltech

Voyager began to feel the increased pressure of interstellar plasma back in 2004 when it detected changes in the outer heliosphere, a vast domain of solar influence extending far beyond the 8 planets. In March 2012 the sun cut loose with a coronal mass ejection or massive burst of solar wind and magnetic fields. When this unexpected gift eventually arrived at Voyager 1′s location 13 months later in April 2013, the plasma around the probe began to vibrate like a plucked violin string. After analyzing the signals, scientists discovered those particular vibrations indicated plasma 40 times denser than the solar variety around Voyager 1 – exactly what was expected for interstellar space.

After review of this event and another weaker one in Nov. 2012, they came to the conclusion that Voyager 1 entered the domain of the stars as early as Aug. 2012.

An image of Voyager 1 taken in the light of radio waves by the National Radio Astronomy Observatory’s 5,000-mile-wide (8,000 km) Very Long Baseline Array (VLBA). It was  made on Feb. 21, 2013. The probe puts out as much power as a small light bulb or ham radio setup. Credit: NRAO/AUI/NSF.

“We literally jumped out of our seats when we saw these oscillations in our data — they showed us the spacecraft was in an entirely new region, comparable to what was expected in interstellar space, and totally different than in the solar bubble,” said Don Gurnett of the  University of Iowa, who led the data analysis.

Voyager is so far away it takes 17 hours for its signal, traveling at the speed of light, to reach the Earth. The signals are very weak – a mere 23 watts or about the same as a kitchen refrigerator light – yet they’re picked up and listened to every day by NASA’s Deep Space Network.


Clip from Star Trek: The Motion Picture featuring “Vger”, the discovery of a Voyager craft by aliens 300 years from now

While there now appears to be no question of Voyager’s transition to interstellar space, it will still feel the effect of the sun’s influence for some time as bubbles of plasma from future solar disturbances barrel through space. No one knows for certain when it will reach interstellar space ruffled only by the mingled winds of alien stars. It’s sister craft, Voyager 2, now 9.5 billion miles (15 billion km) from the sun, will be the next human emissary to the stars.

Voyager 1 continues to take us for a long ride into the vast beyond as it samples interstellar space for the first time. Click pic for more info. Credit: NASA

Voyager 1′s journey may last a billion years or more. As our robotic stand-in, a little bit of me and you get to go along for the long ride.

Picture if you will a brilliant speck of light 15 times brighter than the full moon off to one side of Voyager’s vision. That’s the sun. Now look around and all you see are stars. Lots of them. With no atmosphere to flutter their light, they never twinkle. There’s the familiar band of the Milky Way circling above your head and below. No Earth to get in the way and block the view.

It feels lonely out there, quiet and cold. Our little blue world is such a treasure.

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About astrobob

My name is Bob King and I work at the Duluth News Tribune in Duluth, Minn. as a photographer and photo editor. I'm also an amateur astronomer and have been keen on the sky since age 11. My modest credentials include membership in the American Association of Variable Star Observers (AAVSO) where I'm a regular contributor, International Meteorite Collectors Assn. and Arrowhead Astronomical Society. I also teach community education astronomy classes at our local planetarium.

7 thoughts on “Voyager 1 enters interstellar space, bids solar system farewell!

    • Tim,
      Both Voyagers are powered by the decay of radioactive plutonium 238. The heat given off is converted into electricity. Voyager 1′s current speed relative to the sun is 38,110 mph (99,489 mph relative to Earth). The sun speed is fairly constant but the speed relative to Earth changes – presumably because our planet approaches and recedes from the craft as we orbit the sun. You can find Voyager’s current velocity and other particulars here: http://voyager.jpl.nasa.gov/mission/weekly-reports/

  1. Just amazing. After Voyager 2 our next hope will be for New Horizons to reach interstellar space with a still functioning power source, although at the same distance as Voyager 1 is now it will be traveling approximately 10,000 mph slower.

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