Outer Limits
The solar wind "blows a bubble" in the interstellar medium (the rarefied hydrogen and helium gas that permeates the galaxy). The point where the solar wind's strength is no longer great enough to push back the interstellar medium is known as the heliopause, and is often considered to be the outer "border" of the Solar System. The distance to the heliopause is not precisely known, and probably varies widely depending on the current velocity of the solar wind and the local density of the interstellar medium, but it is known to lie far outside the orbit of Pluto. Scientists hope to gain more perspective on the heliopause from data acquired through the Interstellar Boundary Explorer (IBEX) mission, launched in October 2008.
Read more about this topic: Solar Wind
Famous quotes containing the words outer and/or limits:
“Gillian Taylor: You’re from outer space?
James T. Kirk: No, I’m from Iowa; I work in outer space.”
—Harve Bennett (b. 1930)
“Whatever appeals to the imagination, by transcending the ordinary limits of human ability, wonderfully encourages and liberates us.”
—Ralph Waldo Emerson (1803–1882)