Stars - NASA Science
Stars are giant balls of hot gas – mostly hydrogen, with some helium and small amounts of other elements. Every star has its own life cycle, ranging from a few million to trillions of years, and its properties change as it ages. Stars form in large clouds of gas and dust called molecular clouds.
Star | Definition, Light, Names, & Facts | Britannica
4 天之前 · star, any massive self-luminous celestial body of gas that shines by radiation derived from its internal energy sources. Of the tens of billions of trillions of stars composing the observable universe, only a very small percentage are visible to the naked eye. Many stars occur in pairs, multiple systems, or star clusters.
Star - Wikipedia
Stars are not spread uniformly across the universe but are normally grouped into galaxies along with interstellar gas and dust. A typical large galaxy like the Milky Way contains hundreds of billions of stars. There are more than 2 trillion (10 12) galaxies, though most are less than 10% the mass of the Milky Way. [107]
Star Types - Science@NASA
Types of Stars The universe’s stars range in brightness, size, color, and behavior. Some types change into others very quickly, while others stay relatively unchanged over trillions of years. Main Sequence Stars A normal star forms from a clump of dust and gas in a stellar nursery.
Stars—facts and information - National Geographic
2019年3月20日 · Stars are huge celestial bodies made mostly of hydrogen and helium that produce light and heat from the churning nuclear forges inside their cores. Aside from our sun, the dots of light we see in...
Stars: Facts about stellar formation, history and classification
2022年9月26日 · Stars are giant, luminous spheres of plasma. There are billions of them — including our own sun — in the Milky Way galaxy. And there are billions of galaxies in the universe. So far, we have...
What Are Stars? - NASA
2023年4月19日 · Learn about stars from NASA's High Energy Astrophysics Science Archive Center.