Telescopes around the world are now tracking a new visitor to our celestial neighborhood. Streaking through at a speed and trajectory that not even the Sun's immense gravity can capture, we will only ...

Astronomers are closing in on one of the most tantalizing possibilities in planetary science, evidence that a previously unknown world may be lurking in the outer reaches of the solar system. The ...

Our Sun’s outer atmosphere, the corona, is millions of degrees hotter than it should be, and no one knows why.

At the farthest reach of the Sun’s influence, NASA’s Voyager 1 spacecraft has stumbled into a region that behaves less like empty space and more like a furnace, where charged particles heat to tens of ...