At the farthest edge of the Sun’s influence, the Voyager probes have stumbled into something that sounds almost mythic: a sheath of gas heated to tens of thousands of degrees, a kind of invisible ...

When you buy through links on our articles, Future and its syndication partners may earn a commission. This high-resolution image captured by NASA's New Horizons spacecraft combines blue, red and ...

The boundary of a solar system is not defined by planets, but by gravity. Beyond Pluto and the Kuiper Belt lies the Oort Cloud, extending up to a light year from the Sun and still considered part of ...