NASA says the Hubble Space Telescope, using a new technique to extend our cosmic "tape measure," can accurately gauge the distance to stars 10 times farther away than before.
Hubble, now in its 24th year, has been joined with a technique known as spatial scanning for a dramatic improvement in the space telescope's accuracy when it comes to determining angular measurements.
The new accuracy joins with an age-old distance-measuring method known as astronomical parallax to garner precise distance measurements of stars as far as 10,000 light years from Earth.
The technique opens up new possibilities for exploration of our Milky Way galaxy and the universe beyond, scientists say, with new exploration possibilities.
"This new capability is expected to yield new insight into the nature of dark energy, a mysterious component of space that is pushing the universe apart at an ever-faster rate," says Adam Riess of the Space Telescope Science Institute (STScI) in Baltimore.
The trigonometric technique known as parallax, long a tool of land surveyors, can be extended into outer space by using the orbit of the Earth as a base of a huge triangle, with its two sides meeting at the star as the apex of the triangle.
Stars close to Earth, such as Alpha Centauri, show significant angle changes when measured from two sides of Earth's orbit, making determining its distance fairly easy.
However, for distant stars the changes in the observed angles are much smaller.
Improving the accuracy with which Hubble can measure such angular differences has improved our certainty about the distance to such distant objects.
Scientist used Hubble's new-found precision to nail down the distance to a class of very bright stars known as the Cepheid variables, around 7,500 light years distant in the constellation of Auriga.
Two Hubble images of a target Cepheid example were taken at an interval of six months as the Earth reached opposite points on its orbit around the sun.
The resulting time shift in the position of the star could be measured to a precision of 1/1,000 the width of just one image pixel in Hubble's 16.8-megapixel Wide Field Camera.
The results were so accurate the scientists say they are using Hubble to measure the distance to ever-more far-flung stars.
