New Horizons detects unexpected bright ultraviolet light

A NASA spacecraft, New Horizons, has made a surprising discovery deep in the solar system. After observing a dark area of the sky for over 200 hours, the team found that the background light is much brighter than they expected. However, the reason for this increased brightness is still a mystery. New Horizons was launched in January 2006 to study Pluto and later visited an object called Arrokoth. It is over 61 astronomical units from Earth now, which is about double the distance it was while visiting Pluto. At this distance, the spacecraft is able to study cosmic ultraviolet background radiation without interference from light in the inner solar system. The team used New Horizons' Alice instrument to capture measurements of the ultraviolet light coming from the Milky Way's galactic poles. They were surprised to find that the light in these dark regions is about twice as bright as expected. Some of the brightness can be explained by known sources, like distant stars and galaxies. However, the source of the extra light remains unidentified. This discovery suggests there may be more sources of high-energy ultraviolet light in the galaxy and beyond than scientists currently understand. To learn more, NASA plans to launch a new spacecraft, called UVEX, in 2030, which may help solve this intriguing mystery.