On Aug. 14, 2019, a gravitational wave -- a massive ripple through the fabric of space-time -- washed over the Earth. The wave was detected by sophisticated, fine-tuned lasers in the U.S. and Italy.

Low Earth orbit is full of stuff: not only bits of debris and junk, but also satellites — the number of which is growing rapidly alongside the decreasing cost of launch. This can occasionally pose a ...

Ripples in spacetime have revealed a distant collision between a black hole and a mystery object, which appears too massive to be a neutron star but not massive enough to be a black hole. That ...