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⭐ Life of stars 3D

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Every star starts here

Stellar nebula

Made of
≈ 70% hydrogen, 28% helium, 2% heavier elements, plus dust
Size
Tens to hundreds of light-years
Temperature
≈ −260 °C (10–20 K) in dense cores

Cold clouds of gas and dust. When a dense clump is squeezed — perhaps by a nearby supernova — gravity pulls it together into spinning cores that will become stars.

Example: Orion Nebula (1,344 light-years away); the ‘Pillars of Creation’ in the Eagle Nebula (JWST image, 2022)

  • A star’s mass at birth decides almost everything: its colour, brightness, lifetime and how it dies.
  • Heavier stars are hotter and bluer and burn out much faster. Lightest stars (red dwarfs) are the most common — about 3 in 4 stars — and will shine for trillions of years.
  • Star colours, coolest to hottest: red → orange → yellow → white → blue (types M, K, G, F, A, B, O). The Sun is a G star.
  • The Hertzsprung–Russell diagram (1910s) plots brightness against temperature; most stars sit on a band called the main sequence.