This distance is three times longer than the orbit of Neptune,
the outermost planet in the Solar System.
Gebhardt says the black hole's event horizon — the edge from within nothing can escape, not even light — is four times as large as the orbit of Neptune,
the outermost planet in our solar system.
one of the four enormous
outermost planets in the solar system (Jupiter, Saturn, Neptune, Uranus), composed mostly of gases instead of rock.