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October 16, 2023

A giant “bubble” surrounds our solar system. It’s kept puffed up by the Sun, and it extends far into space. In fact, scientists recently came up with a new estimate of the bubble’s extent: a thousand times the distance from Earth to the Sun.

The bubble is known as the heliosphere. It’s created by the Sun’s magnetic field. A flow of charged particles known as the solar wind streams into space along the lines of magnetic force. As the Sun rotates, the streams spin around like ribbons of water from a lawn sprinkler.

Eventually, the solar wind gives way to particles from interstellar space — the boundary of the heliosphere.

The Voyager 1 and 2 spacecraft have been probing the boundary. The craft are farther from the Sun than any other spacecraft in history. Their observations indicate that they’re in a transition zone. The interstellar magnetic field drapes around the heliosphere like water flowing around the bow of a ship.

Scientists recently combined readings from the Voyagers with those from IBEX — a satellite in Earth orbit that looks for the boundary of the heliosphere. Their work suggests that the transition zone may extend a thousand times the Earth-Sun distance — about a hundred billion miles.

The Voyagers won’t live long enough to reach that boundary. But other probes — in Earth orbit and beyond — should help scientists map the exact extent of the heliosphere.

We’ll talk about an even bigger bubble tomorrow.

Script by Damond Benningfield

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