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How far does the heliosphere extend beyond Neptune’s orbit?

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Space weather Earth's full North Polar auroral oval, in an image taken in ultraviolet light by the U.S. Polar spacecraft over northern Canada, April 6, 1996. In the colour-coded image, which simultaneously shows dayside and nightside auroral activity, the most intense levels of activity are red, and the lowest levels are blue. Polar, launched in February 1996, was designed to further scientists' understanding of how plasma energy contained in the solar wind interacts with Earth's magnetosphere.

The heliosphere extends to a boundary known as the heliopause, which is located approximately 123 astronomical units (AU) from the Sun.12

To understand the scale of this distance beyond Neptune, consider that Neptune orbits at a distance of about 30 AU from the Sun. Therefore, the heliopause extends roughly 93 AU beyond the orbit of Neptune. This boundary marks the region where the outward pressure of the solar wind is balanced by the pressure of the interstellar medium.2