1. The region of space around the Sun dominated by the Sun's magnetic field and solar wind, extending to the heliopause where it meets the interstellar medium.
Usage: astronomy; plural of heliosphere; technical term

Examples

• The heliospheres of different stars vary greatly in size depending on stellar wind strength.
• Scientists study heliospheres to understand how stars interact with the interstellar environment.
• The Voyager probes are exploring the outer boundaries of our Sun's heliosphere.
• Heliospheres provide protection from cosmic rays for planets within them.
• Comparing heliospheres across multiple star systems helps astronomers understand stellar physics.