The 1998 discovery that the universe is expanding at an accelerated rate raised new and profound questions about the nature and fate of the universe. Based on measurements of the speed of distant ...

In the first fractions of a second after the Big Bang, the universe ballooned outward at a speed that still defies explanation, stretching space itself before stars or even atoms had a chance to form.

The 3I/ATLAS comet is only the third object ever identified as entering our solar system from elsewhere in the galaxy. While it poses no threat to Earth and will get no closer than 170 million miles ...