4+ day, 22+ hour ago   (559+ words) In empty space, light travels at exactly 299,792,458 meters per second. That is about 300,000 kilometers per second, or 186,282 miles per second. It is the fastest speed at which matter, energy, or information can travel through the universe. The number is so…...

1+ week, 3+ day ago   (268+ words) Einstein’s theory of general relativity has survived another demanding test. Researchers used clouds of ultracold atoms aboard China’s space station to compare how two forms of rubidium respond to gravity, and found no measurable difference between them. Before your next…...

1+ week, 5+ day ago   (804+ words) Why do planets orbit the Sun instead of falling into it? The short answer is that gravity pulls the planets inward while their sideways motion carries them forward. The combination produces a curved path. A planet is always falling toward…...

2+ week, 3+ day ago   (717+ words) TIC 433545934 contains two pairs of stars locked in a wider orbit. The pairs eclipse internally, and observations also caught one binary crossing the other—a rare geometry that lets astronomers measure four stars together. Astronomers have identified a four-star system…...

4+ week, 1+ day ago   (758+ words) Look up on a clear night and the sky between the stars is mostly black. That seems obvious until you ask a deceptively simple question: if the universe contains an enormous number of stars, why is every direction not filled…...