Scientists have found an unusual "hot spot" centered just below the best-known star constellation visible from Earth, the Plough, which could help explain a decades-long mystery.
The 'blob', situated two hand-widths below the "handle" of the Plough, an arrangement of seven stars within the Great Bear constellation, may shed new light on the origin of ultra-high energy cosmic rays, scientists said.
While lower energy cosmic rays come from stars, the origin of the highest energy rays still cannot be fully explained.
"All we see is a blob in the sky, and inside this blob there is all sorts of stuff - various types of objects that could be the source," said US astronomer Professor Gordon Thomson, from the University of Utah.
"Now we know where to look," added Prof Thomson.