3+ day, 17+ hour ago   (556+ words) A brilliant X-ray source is not automatically a black hole. Matter falling toward a neutron star can also become intensely luminous, and some neutron stars have surprised astronomers by producing far more radiation than expected. Identifying the object requires evidence…...

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…...

5+ day, 22+ hour ago   (624+ words) A neutron star is what remains after the core of a massive star collapses. It is not a small ordinary star. It is the crushed core of a dead one, compressed until protons and electrons are forced together and most…...

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, 4+ day ago   (373+ words) Researchers have completed one of the largest computer simulations of cosmic history yet assembled. Called ASTRID, it follows the growth of galaxies and black holes from the universe’s early days to the present, giving astronomers a virtual laboratory for testing…...

1+ week, 6+ day ago   (754+ words) The explosion is not simply a large firework at the surface. In a massive star, the core has been building heavier elements through nuclear fusion. When the core reaches iron, fusion can no longer provide the energy needed to support…...

3+ week, 2+ day ago   (758+ words) Black holes are invisible until something gives them away. A disk of hot gas can light up around one. A jet can cross a galaxy. And, in the most violent cases, a black hole can tear apart a star and…...

4+ week, 1+ day ago   (818+ words) Sending a spacecraft between stars is difficult for a reason that is easy to underestimate: the spacecraft has to leave one planetary system and arrive at another with enough speed, fuel, and shielding to do useful work. Every kilogram carried…...

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…...