More NASA, ESA, Caltech / ISTOCK / GETTY IMAGES PLUS "[T]he puzzle for theoretical astrophysics ... of a large object passing through the solar system to determine if such a cosmic visitor may ...

This may explain the strange properties of the orbits of our solar system's planets, which are not quite perfectly circular, and all lie on slightly different planes. "[T]he puzzle for theoretical ...

100,000 km deep in space': NASA detects eerie birdsong that could ... Asteroid Bennu’s salts may hold clue to a billion-year-old puzzle 'Bryan Johnson's organs': A 64-year-old ear, but an ...

Play the USA TODAY Daily Crossword Puzzle. Six planets that will be visible ... is "a celestial event where multiple planets in our solar system appear close together in the night sky, visible ...

"We are the first mission to be able to track space weather events in three dimensions routinely across the solar system ... There's also a big puzzle concerning how the solar wind, which ...