Three Invisible Shields

The heliosphere, the magnetosphere and the ozone layer: free, natural protection.

Image: NASA/SDO (Solar Dynamics Observatory), a solar flare seen in six wavelengths.

Last reviewed: 4 sources cited

Impact Statement

Natural solution · active

1. The Heliosphere

The Sun blows a bubble of around the whole solar system. Voyager 1 crossed its edge, the heliopause, on August 25, 2012, at about 122 AU (about 18 billion km) from the Sun, the first human-made object to reach interstellar space. Voyager 2 followed in 2018.

Source: NASA, Voyager Interstellar Mission

NASA's IMAP launched on September 24, 2025 to the L1 point to map that boundary from afar.

Source: NASA, IMAP launch release

2. The Magnetosphere

Earth's magnetic field deflects most of the charged solar wind and helps keep it from stripping away our atmosphere. It is not a perfect wall: strong solar storms still get through and drive geomagnetic storms and auroras.

Source: NASA, Earth's magnetosphere

3. The Atmosphere and Ozone Layer

High in the stratosphere, the layer absorbs most of the Sun's biologically harmful UV-B radiation before it reaches the ground.

Source: NOAA, Ozone basics

These shields are free, natural and have run for billions of years. Our job is to understand them and avoid damaging the one we can: the ozone layer.

The Five W's of Three Invisible Shields

Who

Nature itself: the Sun, Earth's magnetic field and our atmosphere. No organization runs them.

What

Three layers of protection: the heliosphere, the , and the atmosphere with its ozone layer.

When

Running for billions of years, and still working today.

Where

From the edge of the solar system (about 122 AU for Voyager 1's crossing) down to Earth's stratosphere.

Source: NASA, Voyager Interstellar Mission

Why

They deflect the solar wind and absorb most harmful UV-B. The ozone layer is the one we can damage, so it is the one we must protect.

Source: NOAA, Ozone basics

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For Teachers

Discussion questions

  1. What is Three Invisible Shields, and what problem does it help solve?
  2. Who is behind Three Invisible Shields, and where does the work happen?
  3. How does Three Invisible Shields help both people and nature? Use one fact from this page.

Sources are listed with each fact in the Five W's above.

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Cite This Page

APA

Saving Planets. (n.d.). Three Invisible Shields. https://www.savingplanets.com/Three_Shields.html

MLA

"Three Invisible Shields." Saving Planets, https://www.savingplanets.com/Three_Shields.html.

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