The Sun’s Heliosphere

The heliosphere is an immense magnetic bubble, originating from the Sun, surrounding and enveloping our solar system and blocking out many of the dangerous cosmic rays coming from our galaxy. It is depicted here as a bubble in space "blown" into the interstellar medium (the hydrogen and helium gas that permeates the galaxy) by the solar wind. Although electrically neutral atoms from the interstellar medium can penetrate this bubble, virtually all of the material in the heliosphere emanates from the Sun itself. For the first ten billion kilometers of its radius, the solar wind travels at over a million kilometers per hour. As it begins to drop out with the interstellar medium, it slows down before finally ceasing altogether. The point where the solar wind slows down is the Termination Shock. After the Termination Shock is the heliosheath area. Then comes the point where the interstellar medium and solar wind pressures balance – the heliopause. The point where the interstellar medium, traveling in the opposite direction, slows down as it collides with the heliosphere is the bow shock