Graphics for May 23 American Geophysical Union (AGU) Press Conference:
New Discoveries at the Edge of the Solar System
As the 28-year-old Voyagers 1 and 2 spacecraft approach the edge of interstellar space, they have found that the heliosphere, the "bubble" within which the sun dominates, bulges outward in the northern hemisphere and is pressed inward in the south. Voyager 1, flying about 34 degrees north of the equator, crossed the termination shock and entered the outermost layer of the heliosphere about 9 billion miles from the sun. Meanwhile Voyager 2, about 26 degrees south of the equator, finds that the shock may be nearly a billion miles closer to the sun.
Scientists believe that the observed discrepancies may be attributed to an interstellar magnetic field pressing inward on the southern hemisphere. Voyager 2 will determine the exact location of the shock in the south when it crosses it sometime before the end of next year. Then scientists will have a better idea of how strong the magnetic field is outside of the heliospheric bubble.
Voyager 2 is also finding that the shock in the south is a source of low energy ions as was discovered by Voyager 1 in the north. Contrary to earlier predictions, however, neither Voyager 1 nor 2 have found the source of higher energy anomalous cosmic rays.
Both Voyager spacecraft were launched from the Cape Canaveral Air Force Station in Florida: Voyager 2 on Aug. 20, 1977 and Voyager 1 on Sept. 5, 1977 on a faster, shorter trajectory than its twin. The mission is managed for NASA by the Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology.
Slide show: + Selected images from Voyager's planetary tour
Podcast: Voyager - Living on the Edge of the Solar System:
+ Listen now
| + Transcript
For media:+ Related audio clips
Previous Voyager Releases:
+ Voyager Finds Three Surprises Near Our Solar System's Edge (9.23.05)
+ Voyager Enters Solar System's Final Frontier (5.24.05)
+ Voyager Spacecraft Approaching Solar System's Final Frontier (11.05.03)
More Voyager Resources
Video: Voyager Approaching Interstellar Space (cc)
Sound of Solar Wind
Learn More About Where Voyager Is
Solar Blast Blows Past Voyager
What Does the Edge of the Solar System Look Like?
JPL Voyager Home Page
Voyager's Golden Record
The History & Science of Voyager
+ Order the Video News Release (aka "Video File")
Image Left: This still shows the locations of Voyagers 1 and 2. Voyager 1 is traveling a lot and has crossed into the heliosheath, the region where interstellar gas and solar wind start to mix. Click on the image for movie or download color print resolution still and black & white still. Credit: NASA/Walt Feimer|
+ Learn more about where Voyager is
Image Left: Starting with a view of our Milky Way galaxy, the orange gas in the animation represents the interstellar medium. The bow shock is created because the heliosphere is moving through like a boat through the water, crashing through the interstellar gases. The bow shock in front of the moving heliosphere is similar to the one observed by the Hubble Space Telescope. Click for animation. Credit: NASA/Walt Feimer|
Image Left: We don't know the exact location of the termination shock and changes in the solar wind cause it to expand, contract, and ripple like a plate underwater. Water spreads out over the plate in a relatively smooth flow but has a rough edge where the water slows down abruptly and piles up. The edge is like the termination shock, and as the water flow changes, the shape and size of the rough edge change. Credit: NASA/ESA|
Image Left: The Hubble Space Telescope imaged this view in February 1995. The arcing, graceful structure is actually a bow shock about half a light-year across, created from the wind from the star L.L. Orionis colliding with the Orion Nebula flow. For more information on this image, see HubbleSite. Click on the image for a very large version. Credit: NASA, The Hubble Heritage Team (STScI/AURA)|
Image Left:The Voyagers are identical but on different flight paths. Voyager 1 is about 8.7 billion miles from the Sun and traveling at a speed of 3.6 AU per year while Voyager 2 is about 6.5 billion miles away and moving at about 3.3 AU per year. One 'AU' equals the distance between the Sun and Earth, or 93 million miles. In July 2004 scientists used Voyagers to track a solar blast to the edges of the solar system.
Credit: NASA/Walt Feimer|