Finding direction on Earth is easy with GPS, but in space, navigation is a bigger challenge. NASA’s New Horizons, launched in 2006, has now gone beyond 60 times the Earth–Sun distance, where signals from Earth weaken.

A recent study has demonstrated a surprisingly simple solution: using just two stars as reference points. Scientists applied stellar parallax, the apparent shift in a star’s position when viewed from two locations. Just as closing one eye and then the other makes an object appear to move, spacecraft can measure their position by comparing how stars appear from different vantage points.

In April 2020, New Horizons and Earth simultaneously observed Proxima Centauri and Wolf 359, two of the nearest stars. The parallax angles matched closely with distances already known from Earth-based radio tracking, proving the method’s accuracy.

This technique requires no special equipment, just a camera, computer, and star catalog. While it’s not yet precise enough to replace Earth’s tracking networks, it could be vital for future interstellar missions, where Earth-based signals won’t reach.

In essence, the stars themselves could become a cosmic compass, making spacecraft more self-sufficient in navigating the vastness of space.