Scientists have discovered that a barred spiral galaxy located 212 million light-years from the Earth is the largest-known spiral, measuring five times the size of our Milky Way galaxy.

Using archival data from Nasa's Galaxy Evolution Explorer (GALEX) mission, scientists found that measuring tip-to-tip across its two outsized spiral arms, NGC 6872 spans more than 522,000 light-years, making it more than five times the size of our Milky Way galaxy.

"Without GALEX's ability to detect the ultraviolet light of the youngest, hottest stars, we would never have recognised the full extent of this intriguing system," lead scientist Rafael Eufrasio, a research assistant at Nasa's Goddard Space Flight Centre in Greenbelt said.