- medium-sized stars – last for about 10 billion years.
- small stars may last for 200 billion years.
- big stars – it have short, fierce lives of 10 million years.
- stars that begins life in clouds of gas and dust are called nebulae. (photo)
- inside nebulae – gravity creates dark clumps called EGGs – each clump contains the seeds of a family stars. (example)
(Wikipedia: EGGS – evaporating gaseous globules.)
- as gravity squeezes – these globules, they shrink and form hot balls of gas and dust. (video)
- smaller clumps – don’t get very hot, so they eventually fizzle out. (example)
- if larger clump – reaches 10’°c million in its core, hydrogen atoms begin to join together in nuclear reactions and the baby star starts to glow.
- in a medium-sized star such as our Sun, the heat of burning hydrogen pushes gas out as fiercely as gravity pulls inwards, and the star becomes stable (diagram).
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