--- ---  # How NASA Used X-Rays to Pinpoint a Distant Star by [Olivier Laurent](https://time.com/author/olivier-laurent/) ## Olivier Laurent Jun 23, 2015 11:29 PM UTC  A light echo in X-rays detected by NASA’s Chandra X-ray Observatory has provided a rare opportunity to precisely measure the distance to an object on the other side of the Milky Way galaxy. A light echo in X-rays detected by NASA’s Chandra X-ray Observatory has provided a rare opportunity to precisely measure the distance to an object on the other side of the Milky Way galaxy.NASA/CXC/U. Wisconsin/S. Heinz by [Olivier Laurent](https://time.com/author/olivier-laurent/) ## Olivier Laurent Jun 23, 2015 11:29 PM UTC These rings might look like colorful, interstellar rainbows, but for astronomers they’ve helped [solve a mystery](http://www.nasa.gov/press-release/nasa-s-chandra-captures-x-ray-echoes-pinpointing-distant-neutron-star). By studying these rings, which were captured using NASA’s Chandra X-ray Observatory, astronomers were able to determine how far Circinus X-1, a double star system in the plane of our galaxy, is from Earth. “It’s really hard to get accurate distance measurements in astronomy and we only have a handful of methods,” says Sebastian Heinz of the University of Wisconsin in Madison, who led the study. “But just as bats use sonar to triangulate their location, we can use the X-rays from Circinus X-1 to figure out exactly where it is.” The rings are “echoes from a burst of X-rays emitted by Circinus X-1 in late 2013,” the space agency said in a statement. “The burst reflected off intervening clouds of dust, with some reflected X-rays arriving to Earth from different angles at a time delay of about one to three months, creating the observed rings.” By comparing the Chandra data to prior images of dust clouds detected by the Mopra radio telescope in Australia, and by using simple geometry, NASA says that astronomers were able to determine the distance of Circinus X-1 from Earth. In this case: 30,700 light years. ### See the Astronomical League's Most Beautiful Photos from 2014  The Rosette nebula, also known as NGC 2237 or Caldwell 49, taken from Waukesha, Wisc., on Jan. 6, 2014. Dennis Roscoe, Ph.D.  The Elephant's Trunk Nebula, also known as IC 1396, on April 14, 2014. Eric Coles  The Pleiades, also known as M45 or the Seven Sisters, imaged from Fayetteville, Ark., on Jan. 25, 2014. Joel Tonyan  Andromeda Galaxy (M31), imaged from Fayetteville, Ark., on Jan. 19, 2014, Joel Tonyan  A time lapse showing star trails above Big Lagoon State Park in Pensacola, Fla., on March 30, 2014. Kenny Alexander  Eta Aquarid meteors above Bryce Canyon in Utah, in May 2014. David Lane  The Orion Nebula, taken from Waukesha, Wisc., on Feb. 7, 2014. Dennis Roscoe, Ph.D.  A star-forming nebula in Gemini, in January 2014. Brian Peterson  Propeller Nebula in Cygnus, also known as DWB111, on May 1, 2014. Eric Coles  The Milky Way, taken from Pensacola Beach in Pensacola, Fla., on March 2, 2014. Kenny Alexander  An aircraft turns over the night sky with the Milky Way in the background above Santa Rosa Beach, Fla., on Jan. 5, 2014. Matt Jylha  Pelican Nebula, taken from Waukesha, Wisc., on Jan. 9, 2014. Dennis Roscoe, Ph.D.  The Horsehead nebula, also known as Barnard 33 in emission nebula IC 434, taken at Seneca and Oswego in Illinois, Feb.-March 2014 Martin Hrdlicka  A panorama of the Milky Way taken from Fall Creek Falls State Park during the Eta Aquarid meteor shower on May 4, 2014. Matt Harbison  The Rosette nebula, also known as NGC 2237 or Caldwell 49, taken from Seneca, Ill., in March 2014. Martin Hrdlicka  The Pinwheel Galaxy, also known as Messier 101, M101 or NGC 5457, taken at the Winter Star Party in the Florida Keys on March 1, 2014. Richard S. Wright Jr.  The Milky Way with Venus rising at Pensacola Beach in Pensacola, Fla., on March 2, 2014. Kenny Alexander  Waxing Moon over Winter Garden, Fla., on Feb. 10, 2014 Matt Jylha See X-Ray Light Echoes Captured by Chandra Telescope ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/3932920/chandra-xray-light-echoes/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/3932920/chandra-xray-light-echoes/"},"headline":"How NASA Used X-Rays to Pinpoint a Distant Star","datePublished":"2015-06-23T23:29:54.000Z","dateModified":"2026-05-11T05:02:51.666Z","description":"And made this stunning picture","url":"https://time.com/3932920/chandra-xray-light-echoes/","keywords":["Space"],"thumbnailUrl":"https://static.time.com/v3/assets/bltea6093859af6183b/blt9762aab2ee1202d1/69885802a988ca93966b32b0/chandra-xray-light-echoes-neutron-star.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","author":[{"@type":"Person","name":"Olivier Laurent","jobTitle":null,"url":"https://time.com/author/olivier-laurent/"}],"articleSection":"Science","image":[{"@type":"ImageObject","url":"https://static.time.com/v3/assets/bltea6093859af6183b/blt9762aab2ee1202d1/69885802a988ca93966b32b0/chandra-xray-light-echoes-neutron-star.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","width":1200,"height":675,"headline":"Chandra XRay Light Echoes Neutron Star","caption":"Chandra XRay Light Echoes Neutron Star","creditText":"NASA/CXC/U. 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