Today’s AI chatbots are not considered sentient by most researchers. They can write, reason through problems and hold convincing conversations, but there is no solid evidence that they have feelings or experiences. At the same time, scientists do not fully agree on what consciousness is, so the question is debated more seriously than it was … Read more
Many stars do not live alone. A binary star is a pair of stars bound by gravity, orbiting a common center of mass. Roughly half of Sun-like stars have at least one companion, and the share is higher for massive stars. Types by how we detect them Visual binaries: both stars can be seen separately … Read more
Galaxies did not exist at the very beginning. The early universe was a nearly smooth hot gas. Tiny differences in density, visible today in the cosmic microwave background, grew over hundreds of millions of years into the galaxies we see. Dark matter first According to the standard model of cosmology, dark matter clumped first, because … Read more
A neutron star is what remains when a massive star’s core collapses in a supernova. It packs more mass than the Sun into a sphere only about 20 kilometers (12 miles) across, roughly the size of a city. How extreme are they? The core is thought to be made mostly of neutrons, though what happens … Read more
Everything in the solar system moves: planets orbit the Sun, moons orbit planets, and every body spins on its axis. Understanding these motions was one of the first great successes of science, and it is still an active field. The laws of motion Precise orbit calculations led to the discovery of Neptune in 1846, predicted … Read more
The three words are often used interchangeably, and the boundaries really are blurry. Still, each has a distinct emphasis. Astronomy: observing the sky Astronomy is the oldest of the natural sciences. It studies everything beyond Earth’s atmosphere: planets, stars, galaxies and more. Historically, it focused on measuring and observing: positions, motions, brightness and distances. Ancient … Read more
A planet’s magnetic field is invisible, but it reveals what is happening deep inside and protects the planet from the solar wind. Astronomers study these fields mostly with spacecraft, and also through auroras and radio waves. Where do planetary magnetic fields come from? Most come from a dynamo: a flowing, electrically conducting fluid inside a … Read more
The universe is about 13.8 billion years old. That figure comes mainly from measurements of the cosmic microwave background, and it is supported by independent checks on the oldest objects we can see. Method 1: the cosmic microwave background The cosmic microwave background is light released about 380,000 years after the Big Bang. The size … Read more
A solar flare is a sudden, intense burst of radiation from the Sun’s surface, released when tangled magnetic fields near sunspots snap and reconnect. A large flare can release as much energy as billions of nuclear bombs in a few minutes. Flare classes Flares are ranked by their peak X-ray brightness, measured by satellites. Each … Read more
Despite the name, cosmic rays are not rays of light. They are high-energy particles, mostly atomic nuclei, that travel through space at nearly the speed of light and constantly hit Earth’s atmosphere. How cosmic rays were discovered In 1912, Austrian physicist Victor Hess carried instruments up in a balloon and found that radiation increased with … Read more
