Most of the Universe is invisible. Understanding these unseeable elements can be an important step in working out how the entire Universe works.
Charles Alcock, the director of the Harvard Smithsonian Center for Astrophysics, says the Solar System extends far further than first thought. If we define our Solar System as expanding as far as the gravitational field of the Sun dominates, that’s about a thousand times further than we have explored to date.
Alcock is currently exploring the outer limits of our Solar System, beyond the planets Neptune and Pluto. There are billions of small objects in this dark, empty zone – objects that could hold vital clues in understanding how our own planet came into being.
Charles Alcock spoke to BBC Future at the Aspen Ideas Festival. (All background footage courtesy of Nasa)