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 limits, outer and/or limits:
“No one knows better than children how much they need the authority that protects, that sets the outer limits of behavior with known and prescribed consequences. As one little boy expressed it to his mother, “You care what I do.””
—Leontine Young (20th century)
“Once conform, once do what other people do because they do it, and a lethargy steals over all the finer nerves and faculties of the soul. She becomes all outer show and inward emptiness; dull, callous, and indifferent.”
—Virginia Woolf (1882–1941)
“I fear chiefly lest my expression may not be extra-vagant enough, may not wander far enough beyond the narrow limits of my daily experience, so as to be adequate to the truth of which I have been convinced.”
—Henry David Thoreau (1817–1862)