The Universe is everything we can touch, feel, sense, measure or detect. It includes living things, planets, stars, galaxies, dust clouds, light, and even time. ... The Universe contains billions of galaxies, each containing millions or even trillio...
Star are massive balls of plasma, or glowing gas, powered by a process called nuclear fusion, which makes them shine. The life cycle of star depends on its mass. A Sun-sized star can shine for billions of years, while stars with greater mass burn out faster and have shorter lives.
What is a star?
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A star is a giant ball of very hot gas - held together mainly by its gravity. Inside its, hydrogen atoms collide to form helium. This process is called nuclear fusion and it powers the star.
Life cycle Soon after forming, a star begins a long period in which it hardly changes while its core converts hydrogen to helium. When the hydrogen starts to run out, changes in the core create extra and energy and cause the star's outer layer to swell.
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Star magnitude A star's luminosity, or actual brightness, is the amount of energy it gives off per second. How bright a star appears from Earth is called its apparent magnitude. This depends on both the star's luminosity star and its distance from Earth, so even a very luminous star may appear faint in the night sky if it is very far away.
