NASA's Chandra observatory finds evidence of exoplanet outside Milky Way

In a major discovery, the NASA Chandra X-ray Observatory telescope has found evidence for a possible planet outside of the Milky Way galaxy. The "exoplanet" is said to be located in the Whirlpool Galaxy commonly called M51, which is some 28 million light-years away from other "planet candidates" identified by scientists in recent times, NASA said in a statement. There have been discoveries of over 4,000 exoplanets most of which are in the Milky Way galaxy about 3,000 light-years away from Earth.

"Signs of a planet transiting a star outside of the Milky Way galaxy may have been detected for the first time. This intriguing result, using NASA’s Chandra X-ray Observatory, opens up a new window to search for exoplanets at greater distances than ever before," NASA said on Monday. This planet candidate was identified with NASA's Chandra X-ray Observatory that detected a temporary dimming in X-rays in a binary system, where a Sun-like star is in orbit around a neutron star or black hole. "The authors interpret this dimming as being a planet passing in front of the neutron star or black hole," Chandra Observatory said in a statement.

Whole new arena for finding other worlds

Looking for the dimming of a star's light as something passes in front of it is called the transit technique, Chandra Observatory said. "For years, scientists have discovered exoplanets using transits with optical light telescopes, which detect the range of light humans can see with their eyes and more. This includes both ground-based telescopes and space-based ones like NASA's Kepler mission," it added. These optical light transit detections require very high levels of sensitivity because the planet is much smaller than the star it passes in front of, and, therefore, only a tiny fraction of the light is blocked.

“We are trying to open up a whole new arena for finding other worlds by searching for planet candidates at X-ray wavelengths, a strategy that makes it possible to discover them in other galaxies,” said Rosanne Di Stefano of the Center for Astrophysics | Harvard & Smithsonian (CfA) in Cambridge, Massachusetts, who led the study, which was published today in Nature Astronomy.

As per data received by the scientists, it might take decades to determine the size of the planet candidate due to its transit patterns. “Unfortunately to confirm that we’re seeing a planet we would likely have to wait decades to see another transit,” said co-author Nia Imara of the University of California at Santa Cruz. “And because of the uncertainties about how long it takes to orbit, we wouldn't know exactly when to look," she added.

Image: @ChandraXRay_Twitter