Speeding toward interstellar space, NASA’s twin Voyager probes have now truly peered outside the solar system—and they’ve seen something no human has glimpsed before.
According to a new study, the two spacecraft have detected a type of ultraviolet light from other regions of our Milky Way galaxy that had previously been all but invisible due to the sun’s glow.
“People have tried to make this measurement from Earth orbit, unsuccessfully,” said veteran Voyager scientist Bill Sandel of the University of Arizona in Tucson.
The light, a wavelength of ultraviolet called Lyman-alpha radiation, is emitted by hydrogen atoms as they cool down. The radiation is especially intense in stellar nurseries where lots of new stars are forming.