The Heliosphere

"Helio-" means having to do with the Sun...

The heliosphere is the immense magnetic bubble containing our solar system, solar wind, and the entire solar magnetic field. It extends well beyond the orbit of Pluto. While the density of particles in the heliosphere is very low (it's a much better vacuum than is created in a laboratory), it is full of particles of interest to heliospheric scientists. Check out the image below for a diagram of the heliosphere.

More about the Sun's magnetic field...

The solar wind near our Sun's surface contains alternating streams of high and low speed. These streams corotate with the Sun, that is, they rotate along with it. The high-speed streams originate in coronal holes and extend toward the solar poles; the low-speed streams come from near the Sun's equator. There are compositional differences between the high and low speed streams of the solar wind.

With increasing distance from the Sun, the high-speed streams overtake the slower plasma, producing corotating interaction regions (CIRs) on their leading edges. CIRs are bounded by two shocks at the front and rear edges called the forward and reverse shocks. At these shocks, the density, pressure, and magnetic field strength are all higher. These regions are quite effective as energetic particle accelerators. When ions that have been accelerated at a CIR are observed, they are called corotating ion events.

Energetic storm particles (ESPs), accelerated by shocks associated with solar flares and CMEs, are another example of interplanetary acceleration.

The heliopause is the name for the blurred boundary between the heliosphere and the interstellar gas outside the solar system. As the solar wind approaches the heliopause, it slows suddenly, forming a shock wave. This solar wind termination shock is exceptionally good at accelerating particles.

Back to Sun

April 26, 2012: ESA contracts Astrium UK to build Solar Orbiter -- ESA
April 6, 2012: Mysteries of the sun...explained in video -- NASA
March 19, 2012: Solar cycle abundance variations in corotating interaction regions -- ACE News
February 10, 2012: Alien matter in the solar system: A galactic mismatch -- Science@NASA
February 4, 2012: IBEX glimpses alien interstellar material -- Astrobiology
January 31, 2012: IBEX: Glimpses of the interstellar material beyond our solar system -- NASA
December 26, 2011: Voyager 1 speeds toward the brink of interstellar space -- NPR
December 10, 2011: Voyager enters cosmic purgatory -- Astrobiology
December 5, 2011: The return of energetic 3He in the inner heliosphere -- ACE News
December 5, 2011: Voyager sets sights on Milky Way -- Physics World
June 18, 2011: Voyager on the edge -- Astrobiology
May 6, 2011: Farther along -- APOD
April 29, 2011: Messages from the edge of the solar system -- Astrobiology
March 31, 2011: IBEX scientists isolate mysterious 'ribbon' of energy and particles that wraps around heliosphere -- Eurekalert
December 15, 2010: Voyager crosses the point of solar stillness -- Astrobiology
December 13, 2010: NASA probe sees solar wind decline -- NASA
October 2, 2010: The ever-changing edge of the solar system -- Astrobiology
October 1, 2010: Sun's heliopause: A moving target -- Sky & Telescope
September 30, 2010: IBEX finds surprising changes at solar boundary -- NASA
September 2, 2010: The sun's magnetic field warps its environment -- Physics World
August 17, 2010: IBEX maps the boundaries -- Astrobiology
August 17, 2010: IBEX mapping mission yields intriguing new studies about our solar system -- Astronomy
August 16, 2010: IBEX spacecraft finds discoveries close to home -- NASA
June 28, 2010: Voyager 2 at 12,000 days: The super-marathon continues -- NASA
February 16, 2010: Voyager's group portrait -- Astrobiology magazine
January 15, 2010: Giant ribbon at the edge of the solar system: Mystery solved? -- Science@NASA
January 12, 2010: Solar scientists use 'magnetic mirror effect' to reproduce IBEX observation -- NASA
December 23, 2009: Voyager makes an interstellar discovery -- Science@NASA
December 8, 2009: View from the center of the solar system -- Astrobiology magazine
November 9, 2009: The stars my destination -- Astrobiology Magazine
October 19, 2009: Edge effect -- HEAPOW
October 15, 2009: Mystery space "ribbon" found at solar system's edge -- National Geographic
October 15, 2009: Giant ribbon discovered at the edge of the solar system -- Science@NASA
October 15, 2009: Cassini helps redraw shape of solar system -- JHU APL
September 1, 2009: Salvaging NASA's planetary Grand Tour: Sending Voyager 2 where no probe had gone before -- or since -- Scientific American
August 3, 2009: NASA debuts 'Sentinels of the Heliosphere' film in New Orleans -- NASA GSFC
July 28, 2009: Space aged: 10 spacecraft from decades past that are still ticking -- Voyagers 1 and 2 (1977) -- Scientific American
June 30, 2009: Ulysses: 12 extra months of valuable science -- ESA
January 13, 2009: First all-sky map of the edge of the Solar System -- Astronomy.com
December 19, 2008: Explore the entire region of the Sun's influence with NASA's 'Heliophysics Virtual Observatories' -- NASA
October 19, 2008: NASA launches IBEX mission to outer Solar System -- NASA
October 6, 2008: NASA spacecraft ready to explore outer Solar System -- NASA
July 25, 2008: 'Impressionist' spacecraft to view solar system's invisible frontier -- NASA
July 9, 2008: Voyager 2 finds edge of solar system more complex than predicted -- JHU APL
July 2, 2008: STEREO creates first images of the solar system's invisible frontier -- NASA
July 2, 2008: Who knew? Solar system is 'dented', not round -- CNN
February 22, 2008: International solar mission to end following stellar performance -- NASA
January 18, 2008: Abundances and energy spectra of CIR heavy ions during Solar Cycle 23 -- ACE News
December 13, 2007: Voyager 2 reaches the heliosphere -- AIP
December 12, 2007: Surprises at the solar system's edge -- Astronomy.com
December 10, 2007: Voyager 2 probe leaves the neighborhood -- Nature
December 10, 2007: MIT instrument finds surprises at solar system's edge -- MIT
November 28, 2007: Voyager 2 nears threshold at edge of solar system -- Canadian Broadcasting Company
August 31, 2007: Celebrating 10 years of ACE in space -- ACE News
August 30, 2007: Pioneering NASA spacecraft mark thirty years of flight -- Science Daily
August 20, 2007: Pioneering NASA spacecraft mark thirty years of flight -- NASA JPL
August 17, 2007: In search of interstellar dragon fire -- NASA GSFC
November 17, 2006: Ulysses embarks on third set of polar passes -- European Space Agency
November 16, 2006: Learning the magnetic ropes -- Los Alamos National Laboratory
September 21, 2006: Surprises from the edge of the solar system -- Science@NASA
May 23, 2006: Voyager 2 detects odd shape of solar system's edge -- Space.com
May 23, 2006: Voyager: living on the edge - of the solar system -- NASA JPL
October 7, 2005: Ulysses, fifteen years and going strong -- SpaceRef.com
September 27, 2005: Voyager finds three surprises near our solar system's edge -- PhysOrg.com
September 26, 2005: Voyager 1: messages from the edge -- SpaceRef.com
June 2, 2005: Voyager 1 at solar system edge, scientists now agree -- National Geographic News
May 27, 2005: Reaching the solar system's edge -- Astronomy.com
May 24, 2005: Voyager spacecraft enters solar system's final frontier -- NASA JPL
March 15, 2005: The distortion of the heliosphere: our interstellar magnetic compass -- SpaceRef.com
March 3, 2005: NASA study suggests giant space clouds iced Earth -- NASA HQ
October 9, 2004: The flow of interstellar helium in the solar system -- SpaceRef.com
September 27, 2004: Shields up! -- Science@NASA
September 20, 2004: The flow of interstellar helium in the solar system -- European Space Agency
July 9, 2004: Blast waves near edge of system -- Florida Today
July 8, 2004: Spacecraft fleet tracks blast wave through solar system -- NASA GSFC
February 14, 2004: Ulysses mission extended -- Spaceflight Now
January 3, 2004: Next stop, interstellar space -- Science News
November 20, 2003: Voyager at 90 AU -- NASA GSFC APOD
November 5, 2003: What does the edge of the solar system look like? Ask Voyager. -- NASA
November 5, 2003: Voyager spacecraft approaches solar system's final frontier -- NASA JPL
September 22, 2003: Merged Interaction Regions (MIRs) at 1 AU -- ACE News
July 17, 2003: Interstellar and heliospheric parameters derived from observations of pickup helium in the focusing cone -- ACE News
April 9, 2003: Maintenance on Voyager from 7 billion miles away -- Spaceflight Now
January 2: Suprathermal electrons in high-speed streams -- ACE News
August 16, 2002: 25 years later, Voyager mission keeps pushing the space envelope -- NASA JPL
July 22, 2002: The little spacecraft that could...and did -- Scientific American
June 24, 2002: The Sun's heliosphere & heliopause -- NASA GSFC APOD
April 18, 2002: Beyond Pluto, NASA craft keeps on trekking -- CNN.com
April 9, 2002: Record set for most-distant spacecraft maintenance -- NASA JPL
March 13, 2002: LL Orionis: When cosmic winds collide -- NASA GSFC APOD
March 6, 2002: Hubble eyes bow shock near a young star -- NASA JPL
October 11, 2001: Ulysses reaches the Sun's north pole -- ESA
December 19, 2000: Most distant spacecraft may reach shock zone soon -- Spaceflight Now
December 18, 2000: Most distant spacecraft may reach shock zone soon -- NASA JPL
November 28, 2000: BZ Cam bow shock -- NASA GSFC APOD
October 17, 2000: Gemini North images bow shock near galactic center -- NASA GSFC APOD
September 6, 2000: Ulysses studies the Sun's polar cap at sunspot maximum -- NASA JPL
June 15, 2000: Officials seek to extend Ulysses sun probe mission -- Spaceflight Now