Where the solar system ends

The closest thing our Solar System has to an “end” is the point where the Sun’s solar wind no longer has influence — we call this interstellar space, or the space between stars.

At this distance, we get to the edge of the heliosphere, or the “bubble” caused by charged particles streaming from the Sun (known as solar wind).

NASA’s New Horizons spacecraft, which took the first up-close pictures of Pluto back in 2015, has been observing interstellar space from the Kuiper Belt.

New Horizons studies particles from those cosmic rays that have interacted with the solar wind as they stream into our Solar System from interstellar space.

With those measurements, New Horizons scientists recently discovered that the Sun whirls around the Milky Way in a relatively thick soup of interstellar medium.

They figured out that the interstellar medium outside our Solar System contains much more hydrogen than scientists originally thought.

This is the first time we’ve studied these particles from so close (relatively) to the edge of our cosmic neighborhood.