Many other stars are visible to the naked eye at night Their immense distances from earth make them appear as fixed points of light. Of the tens of billions of trillions of stars in the observable universe, only a very small percentage are visible to the naked eye. A star is a luminous ball of gas, mostly hydrogen and helium, held together by its own gravity Nuclear fusion reactions in its core support the star against gravity and produce photons and heat, as well as small amounts of heavier elements. These large, swelling stars are known as red giants
But there are different ways a star’s life can end, and its fate depends on how massive the star is. A star is a huge sphere of very hot, glowing gas Stars produce their own light and energy by a process called nuclear fusion Fusion happens when lighter elements are forced to become heavier elements When this happens, a tremendous amount of energy is created causing the star to heat up and shine Stars come in a variety of sizes and colors.
Where do stars come from Every star forms in a huge cloud of gas and dust Over time, gravity causes the cloud to contract, drawing the gas closer and closer together As more gas accumulates at the center, it becomes denser and pressure increases This causes it to heat up and begin to glow. Somewhat related to star clusters are stellar associations, which consist of loose groups of physically similar stars that have insufficient mass as a group to remain together as an organization
This is a list of significant stars ordered alphabetically by the constellations in which they appear, followed by a list of significant star types. Throughout the milky way galaxy (and even near the sun itself), astronomers have discovered stars that are well evolved or even approaching extinction, or both, as well as occasional stars that must be very young or still in the process of formation.
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