NASA’s New Horizons space probe is currently the farthest human-made object that still able to take photographs. It was launched on January 19, 2006. As of June 14, 2020, it is about 6.973 billion kilometers (4.332 billion miles) away from Earth. This is about 46.61 AU, or Astronomical Unit, the distance between the Earth and the Sun, which is equal to about 150 million kilometers (93 million miles). Light takes 6 hours, 27 minutes, and 39.5936 seconds to travel from New Horizons and arrive at us. It is so far that the photos taken by New Horizons show nearby stars from an unearthly perspective.

An unearthly parallax perspective

Yes, for the first time ever, a spacecraft has sent back pictures of the sky from so far away that the nearby stars appear to be in different positions than we’d see from Earth. New Horizons spacecraft just observed interstellar parallax from the outer reaches of the solar system.

On December 5, 2017, New Horizons broke the record for Voyager 1’s record for being farthest from Earth while capturing images. It is still taking photos and the images of the star Proxima Centauri captured by it show the star from a different perspective than the images captured by ground-based telescopes.

On April 22-23, 2020, the spacecraft turned its long-range telescopic camera to a pair of the closest stars, Proxima Centauri and Wolf 359, showing just how they appear in different places than we see from Earth. Scientists have long used this “parallax effect” – how a star appears to shift against its background when seen from different locations – to measure distances to stars: as Earth makes its way around the Sun, the stars shift their positions.

But, because even the nearest stars are hundreds of thousands of times farther away than the diameter of Earth’s orbit, the parallax shifts are tiny, and can only be measured with precise instrumentation – no human eye can detect these shifts.

When images taken by New Horizons are paired with images of the same stars taken on the same dates by ground-based telescopes on Earth, the parallax shift is instantly and clearly visible – even to human eye. The combination yields a perfect 3D view of the stars “floating” in front of their background star fields.

Images of the nearby star Proxima Centauri captured by New Horizons and a ground-based telescope
Images of the nearby star Proxima Centauri captured by New Horizons and a ground-based telescope merged into a single GIF. Image credit: NASA/Johns Hopkins Applied Physics Laboratory/Southwest Research Institute/Las Cumbres Observatory/Siding Spring Observatory

New Horizons is not the farthest human-made object though – this title goes to Voyager 1. It was launched by NASA on September 5, 1977, and as of June 2020, Voyager 1 is more than 13,8 billion miles (22,2 billion km) or 148.64 AU from Earth. It stopped taking photos three decades ago.

After taking its last but most famous image, the “Solar System Family Portrait” or better known as “Pale Blue Dot” in 1990, the cameras of Voyager 1 were turned off to save power and memory for the instruments expected to detect the new charged particle environment of interstellar space. Mission managers removed the software from both Voyager 1 and Voyager 2 spacecraft that controls the cameras.

How long we’ll be able to communicate with the New Horizons spacecraft?

Despite we can communicate out to 200 AU (we’re currently near 47 AU), its power will run out before we get that far, somewhere near 100 AU. And there’s no way to get additional power. The spacecraft’s power is generated by a lump of decaying plutonium and once it decays away it’s gone.

Create your own New Horizons parallax perspectives

You can download images taken by the New Horizons spacecraft and create or own parallax perspectives. Learn more.

Brian May looking at New Horizons' images
New Horizons contributing scientist, astrophysicist and legendary Queen guitarist Brian May uses an OWL viewer to check out the stereo images of Proxima Centauri he created by combining pictures from Earth-based telescopes and the New Horizons spacecraft.

Sources

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