Our Solar System lies inside a mysterious protective bubble and scientists have mapped its edge

Imagine living inside a giant invisible shield. Our Solar System is wrapped in such a shield, a bubble created by the Sun. Known as the heliosphere, it extends billions of kilometres into space and protects life on Earth. Until recently, its hidden boundaries remained largely uncertain.

What is the heliosphere?
The heliosphere is shaped by the solar wind, streams of charged particles flowing outward from the Sun. This immense bubble separates us from interstellar space. At about 100 astronomical units, the solar wind slows after meeting interstellar gas. This invisible boundary is called the termination shock.

What did the new study reveal?
An international study in Nature Astronomy has now mapped this region. Using data from NASA’s Interstellar Boundary Explorer spacecraft, scientists surveyed the termination shock’s strength and shape. Earlier, only NASA’s Voyager probes measured two narrow paths as they exited the Solar System. Now, researchers can see the structure globally.

The study found the shock is not uniform. It is stronger and more compressed near the Sun’s poles. This is most noticeable during solar minimum, when polar winds are faster and more forceful. Along the flanks, the shock is weaker because the solar wind slows after interacting with more material.

What shapes the heliosphere’s structure?
Data revealed a north-south asymmetry across the heliosphere. This is linked to changes in the Sun’s magnetic field. Polar coronal holes, where magnetic fields open into space, play a key role. These holes allow solar wind to escape more freely and shape the bubble’s form.