The Scale of the Heliosphere and Nearby Galactic Neighborhood

The solar system and its nearby galactic neighborhood are illustrated here on a logarithmic scale extending (from < 1 to) 1 million Astornomical Units (AU). Our Sun and its planets are shielded by a bubble of solar wind - the heliosphere - that is about 100 AU in size. The actual boundary between solar wind and interstellar plasma is called the heliopause. Beyond this bubble is a largely unknown region - the interstellar medium. Threaded through the boundaries of the heliosphere is the Kuiper Belt - the source of short-period comets. The nearest edge of the interstellar cloud that presently surrounds our solar system is thought to be several thousand AU away. The Oort Cloud is a spherical shell of comets extending from <10,000 to ~100,000 AU - the edge of our Sun's gravitational spere of influence. Alpha-Centauri, the best known member of our nearest star system, lies well beyond at ~300,000 AU. Interstellar Probe is to be man's first spacecraft designed to exit the heliosphere and begin the exploration of the interstellar medium.



Interstellar Medium
Interaction Between the Interstellar Medium and the Solar Wind
The Outer Solar System
Scientific Instruments and Mission Requirements
Table of Contents


For more information regarding this website
and the Interstellar Probe Project,
please contact Dr. Paulett Liewer

This site was last updated:
February 8, 2000.