heliosphere

noun

he·​li·​o·​sphere ˈhē-lē-ə-ˌsfir How to pronounce heliosphere (audio) -ō- How to pronounce heliosphere (audio)
: the region in space influenced by the sun or solar wind
heliospheric
ˌhē-lē-ə-ˈsfir-ik How to pronounce heliosphere (audio)
-ˈsfer-
-lē-ō-
adjective

Examples of heliosphere in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
This X-ray glow is radiated when the heavy ions of the solar wind, like carbon and oxygen, grab an electron from neutral atoms in either our outer atmosphere or the heliosphere. Robert Lea, Space.com, 24 Apr. 2026 To infinity and beyond A SpaceX Falcon 9 rocket is prepared for launch carrying NASA's IMAP mission, which will study the boundary of the sun's heliosphere and other scientific payloads, at the Kennedy Space Center in Cape Canaveral, Florida, Sept. 23, 2025. Alex Harring, CNBC, 26 Mar. 2026 The space agency's Interstellar Mapping and Acceleration Probe, or IMAP, is expected to continue its mission for two years, using scientific instruments to chart the boundaries of the heliosphere and what's going on inside of it. Emily Mae Czachor, CBS News, 3 Feb. 2026 Since entering interstellar space, the craft has been studying plasma waves, cosmic rays and magnetic fields in the heliosphere, the immense bubble of solar wind around the solar system. George Petras, USA Today, 25 Nov. 2025 See All Example Sentences for heliosphere

Word History

Etymology

helio- + -sphere

First Known Use

1967, in the meaning defined above

Time Traveler
The first known use of heliosphere was in 1967

Browse Nearby Words

Cite this Entry

“Heliosphere.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/heliosphere. Accessed 2 May. 2026.

Kids Definition

heliosphere

noun
he·​li·​o·​sphere ˈhē-lē-ə-ˌsfir How to pronounce heliosphere (audio) -ō- How to pronounce heliosphere (audio)
: the region of space that is affected by the sun or solar wind

More from Merriam-Webster on heliosphere

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

More from Merriam-Webster