(News from JHUAPL)
For the first time, a spacecraft has sent back pictures of the sky from so far away that some stars appear to be in different positions than we see from Earth.
More than four billion miles from home and speeding toward interstellar space, NASA’s New Horizons has traveled so far that it now has a unique view of the nearest stars. “It’s fair to say that New Horizons is looking at an alien sky, unlike what we see from Earth,” said Alan Stern, New Horizons principal investigator from Southwest Research Institute (SwRI) in Boulder, Colorado. “And that has allowed us to do something that had never been accomplished before — to see the nearest stars visibly displaced on the sky from the positions we see them on Earth.”
On April 22–23, [New Horizons] 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.
When New Horizons images are paired with pictures of the same stars taken on the same dates by telescopes on Earth, the parallax shift is instantly visible. The combination yields a 3D view of the stars “floating” in front of their background star fields.
“The sky is starting to look alien to New Horizons as it leaves the skies of home behind forever. We can see this and measure it. We have traveled so far, that from now on we navigate not by how the stars are the same, but how they are different…”
— Tod Lauer, New Horizons science team member