What does 'heliosphere' mean?

The word heliosphere describes the region of space influenced by the solar wind.

Science word of the day: Heliosphere

Pronunciation: HEE'-lee-uhs-feer

What it means: The heliosphere is the region around the sun that's affected by the solar wind, a flow of charged particles emanating from the sun. Think of the heliosphere like a giant bubble encompassing the sun and planets, reaching out into space at three times the distance of Pluto. This bubble protects the solar system from radiation emanating from outer space, but the solar wind can also erode planetary atmospheres. Luckily, Earth is protected by its own bubble, the magnetosphere, which helps deflect the solar wind.

How to use it in a sentence: Because the entire solar system is traveling through space, scientists have long pictured the heliosphere as comet-shaped, but recent research suggests the bubble of solar wind looks more like a sad, deflated croissant.