[ hee-lee-uh-sfeer ]
/ ˈhi li əˌsfɪər /

noun Astronomy.

the region around the sun over which the effect of the solar wind extends.

Origin of heliosphere

First recorded in 1970–75; helio- + -sphere
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for heliosphere


/ (ˈhiːlɪəʊˌsfɪə) /


the region around the sun outside of which the sun's influence is negligible and interstellar space begins
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Science definitions for heliosphere


[ hēlē-ə-sfîr′ ]

The large, roughly elliptical region of space around the Sun through which the solar wind extends and through which the Sun exerts a magnetic influence. The heliosphere extends well beyond the orbits of the planets, and its shape and extent fluctuate with changes to the solar wind and other influences.♦ The boundary between the heliosphere and interstellar space is known as the heliopause.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.