LOS ANGELES — The unstoppable Voyager 1 spacecraft has sailed into a new realm of the solar system that scientists did not know existed.

Voyager 1 and its twin, Voyager 2, have been speeding away from the sun toward interstellar space, or the space between stars.

Over the summer, Voyager 1, which is farther along in its journey, crossed into this new region where the effects from the outside can be felt.