Title: The Heliospheric Termination Shock Authors: R. A. Treumann, C. H. Jaroschek
The heliospheric Termination Shock is the largest (by dimension) shock in the heliosphere. It is believed that it is also the strongest shock and is responsible for the generation of the Anomalous Cosmic Ray component in the heliosphere. This chapter review the gross properties and observations of the Termination Shock. It is structured as follows: 1. The heliosphere, providing the heliospheric stage for Termination Shock formation, 2. The argument for a heliospheric Termination Shock, 3. The global heliospheric system, 4. Termination Shock properties, 5. Observations: the Voyager passages, radio observations, plasma waves and electron beams, traces of plasma and magnetic field, energetic particles, galactic cosmic rays, Termination Shock particles, the anomalous cosmic ray component, 6. Conclusions.
The Voyager 1 and 2 spacecraft have travelled beyond the edges of the bubble in space where the sun's constant outward wind of particles and radiation slams into the interstellar medium that pervades our galaxy. The first scientific reports on what the Voyagers found there appears this week in the journal Nature. The deep-space probes, which were designed mainly to study the outer planets Jupiter, Saturn, Uranus and Neptune, have now travelled more than 8 billion miles away from the Earth. Voyager 1 is now more than 94 Astronomical Units away (one AU is the average distance from the Earth to the sun, or 93 million miles), and Voyager 2 is more than 84 AU. Because they are leaving the solar system on paths that are about 45 degrees apart, the data reveals details about the shape of the bubble created by the solar wind. The fact that they crossed the edge of the solar outflow--a region called the boundary shock--at different distances out from the sun proved that this bubble is squashed rather than being a symmetrical sphere.
This image shows the positions and trajectories of Voyager 1 (at 94 Astronomical Units from the sun) and Voyager 2 (at 84 Astronomical Units) as they pass through the termination shock at the edge of our solar system. Readings from the two probes indicate that the solar system is "dented" due to the dynamics of the solar wind. Credit Opher et al. 2006 via NASA
NASA's Voyager 2 spacecraft has followed its twin Voyager 1 into the solar system's final frontier, a vast region at the edge of our solar system where the solar wind runs up against the thin gas between the stars. However, Voyager 2 took a different path, entering this region, called the heliosheath, on August 30, 2007. Because Voyager 2 crossed the heliosheath boundary, called the solar wind termination shock, about 10 billion miles away from Voyager 1 and almost a billion miles closer to the sun, it confirmed that our solar system is "squashed" or "dented" -- that the bubble carved into interstellar space by the solar wind is not perfectly round. Where Voyager 2 made its crossing, the bubble is pushed in closer to the sun by the local interstellar magnetic field.
"Voyager 2 continues its journey of discovery, crossing the termination shock multiple times as it entered the outermost layer of the giant heliospheric bubble surrounding the Sun and joined Voyager 1 in the last leg of the race to interstellar space" - Voyager Project Scientist Dr. Edward Stone of the California Institute of Technology, Pasadena, California.
Thirty years ago, the Voyager spacecraft were launched. Their mission was to head straight out from Earth into deep space, where they would broadcast songs by whales, messages from Jimmy Carter and directions to Earth, in the hope than an alien culture would drop by for tea and biscuits. The little ships are doing well. Voyager 1 is around 9.6 billion miles from the sun, doing just over 38,000mph through the termination shock region between the edge of our solar system and interstellar space. Voyager 2 is way beyond Pluto, forging a path through the myriad tiny ice planets that cling precariously to the suns gravity. Its all just too excellent for words, the notion that weve sent a message in a bottle out there and now its just a question of waiting for Mr Spock to land in Hyde Park.
If ever our civilization destroys itself and Earth succumbs to a nuclear winter, at least two relics of our best qualities will remain, far removed from their troubled home. With a little luck, someone - or something - might find these curious items, decipher their hieroglyphics and learn about the long-deceased inhabitants of a faraway world.
A mission that was supposed to last just five years is celebrating its 30th anniversary this fall. Scientists continue to receive data from the Voyager 1 and 2 spacecraft as they approach interstellar space. The twin craft have become a fixture of pop culture, inspiring novels and playing a central role in television shows, music videos, songs and movies from the 1980s and 1990s. Many of these fictional works focus on what would happen if an alien race were able to locate Earth via Voyager's famous golden records, which include sounds and images of Earth. The selections portray people young and old, male and female -- not to mention examples of many other species -- and include information about every continent on the planet, as well as Earth's location in space.
NASA's two venerable Voyager spacecraft are celebrating three decades of flight as they head toward interstellar space. Their ongoing odysseys mark an unprecedented and historic accomplishment. Voyager 2 launched on Aug. 20, 1977, and Voyager 1 launched on Sept. 5, 1977. They continue to return information from distances more than three times farther away than Pluto.
Title: The Orientation of the Local Interstellar Magnetic Field Authors: M. Opher, E. C. Stone, T. I. Gombosi
The orientation of the local interstellar magnetic field introduces asymmetries in the heliosphere that affect the location of heliospheric radio emissions and the streaming direction of ions from the termination shock of the solar wind. We combine observations of radio emissions and energetic particle streaming with extensive 3D MHD computer simulations of magnetic field draping over the heliopause to show that the plane of the local interstellar field is ~ 60-90 degrees from the galactic plane. This suggests that the field orientation in the Local Interstellar Cloud differs from that of a larger scale interstellar magnetic field thought to parallel the galactic plane.
A mind-blowing finding has defied the age-old textbook information on the shape of our solar system i.e. its being elliptical which defines the shape of an egg, with the Sun at the centre of it. NASA has recently come up with its new claim that our solar system is bullet shaped and not elliptical! Thanks to the data collected by two Voyager spacecraft of NASA.