The view from beyond Pluto is far enough from Earth that we can see the stars shift.
NASA’s New Horizons, humanity’s first spacecraft to encounter Pluto, is more than 4.3 billion miles (7 billion km) from Earth.
At these incredible distances, the closest stars shift configurations relative to more distant background objects.
The same effect occurs when you alternate which eye views your thumb: parallax.
With enough distance between your proverbial “eyes,” the closest stars to Earth appear to move.
The parallax method is the most reliable way to calculate the distance to the stars.
No spacecraft equipped with a functioning, high-resolution camera has ever been as distant as New Horizons presently is.
On April 22/23, Earth and New Horizons simultaneously observed two relatively close stars.
The first was Proxima Centauri, the closest star beyond the Sun: 4.24 light-years away.
Its observed shift of 32 arc-seconds is the greatest stellar parallax ever measured.
For comparison, Proxima Centauri appeared to move by more than the angular size of Mars or Saturn from Earth’s perspective.
The second target, Wolf 359, is nearly twice as distant: 7.86 light-years away.
Its shift is barely half of Proxima Centauri’s, but still measurable.
ESA’s Gaia mission significantly surpasses this precision.
Despite shorter baselines, it’s identified parallaxes for over 1 billion stars.
Mostly Mute Monday tells an astronomical story in images, visuals and no more than 200 words. Talk less; smile more.Ethan Siegel is the author of Beyond the Galaxy and Treknology. You can pre-order his third book, currently in development: the Encyclopaedia Cosmologica.