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
ˌhē-lē-ə-ˈsfir-ik How to pronounce heliosphere (audio)

Examples of heliosphere in a Sentence

Recent Examples on the Web Where is Voyager 2? Voyager 2, which is nearly 46 years into its mission, is roughly 12.4 billion miles from Earth after leaving the heliosphere — the shield that protects the planets from interstellar radiation — five years ago, according to NASA. Eric Lagatta, USA TODAY, 7 Aug. 2023 In 2018, the spacecraft left the heliosphere, which is the outer layer of particles and magnetic field created by the sun, according to NASA. Eric Lagatta, USA TODAY, 3 Aug. 2023 The blowing of the solar wind creates an enormous magnetic bubble around the Sun, known as the heliosphere. Corey S. Powell, Discover Magazine, 31 Jan. 2021 From that measurement scientists determined that the plasma was more than 40 times denser than what Voyager had encountered in the outer layer of the heliosphere — a density on par with that expected in interstellar space. Lisa Raffensperger, Discover Magazine, 12 Sep. 2013 Both are in interstellar space and the only spacecraft to operate beyond the heliosphere, the sun’s bubble of magnetic fields and particles that extends well beyond the orbit of Pluto. Ashley Strickland, CNN, 10 May 2023 On October 5, NASA reported that their Voyager 2 spacecraft is nearing our heliosphere’s outer borders, and could soon enter interstellar space. Amber Jorgenson, Discover Magazine, 8 Oct. 2018 Astronomers expected there might be a difference between the magnetic field direction inside the heliosphere, where magnetic fields come from the sun, and outside of it, where magnetic fields come from exploding stars spewing their magnetic fields into surrounding material. Erika K. Carlson, Discover Magazine, 4 Nov. 2019 How big is the heliosphere? Jamie Carter, Forbes, 18 June 2021 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'heliosphere.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


helio- + -sphere

First Known Use

1967, in the meaning defined above

Time Traveler
The first known use of heliosphere was in 1967

Dictionary Entries Near heliosphere

Cite this Entry

“Heliosphere.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/heliosphere. Accessed 4 Oct. 2023.

Kids Definition


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

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