Our environment in the solar system

What safeguards our solar system is our star. The Sun provides a shield, stretching beyond the last planet in its orbit: a force field that deflects these cosmic rays. But these solar winds can be dangerous too, especially during outbursts called coronal mass ejections.

Want a vision of Earth gone wrong? Just look at what solar storms do to our sister planet, Venus. They strip away lighter elements in its upper atmosphere: hydrogen, oxygen, and the molecule they form: water. What’s left is a witch’s brew of noxious chemicals including thick sulfurous clouds.

How has Earth avoided the grim fate of Venus? We can see the answer as the solar storm approaches Earth. Our planet has a protective shield all its own: a powerful magnetic field generated deep within its core. In fact, that’s just our first line of defence. Much of the solar energy that gets through is reflected back to space by clouds, ice and snow. The energy that Earth absorbs is just enough to power a remarkable planetary engine: the climate.

It’s set in motion by the unevenness of solar heating, due in part to the cycles of day and night, and the seasons that causes warm tropical winds to blow towards the poles and cold polar air toward the equator. Wind currents drive surface ocean currents. This computer simulation shows the Gulf Stream winding its way along the coast of North America.

This great ocean river carries enough heat energy to power the industrial world a hundred times over. It breaks down in massive whirlpools that spread warm tropical waters over northern seas. Below the surface they mix with cold deep currents that swirl around under sea ledges and mountains.

Earth’s climate engine has countless moving parts: tides and terrain, crosswinds and currents, all working to equalise temperatures around the globe.