From Brian Ball
In the argument over whether Voyager 1 has left the solar system, many different definitions of where that boundary lies were discussed (5 April, p 39). But to me, the most obvious suggestion was the one disregarded early on, the Oort cloud.
Shouldn’t the end of the solar system be where the sun’s tangible effects, most notably its gravity, are reduced to nothing? It is after all called the solar system.
Boulder, Colorado, US
