On February 23, 1990, NASA's Pioneer 11 spacecraft left the solar system! This was the second spacecraft to travel beyond the ...

Documents might help scientists shed light on unexplained phenomena and government secrets, experts said.

Skygazers can usually spot two or three planets after sunset, according to NASA. Hangouts of four or five that can be glimpsed with the naked eye are less common and occur every f ...

Something big appears to be warping the orbital plane of the Kuiper Belt. We can’t see it, but if some unobserved beast is ...