Space Encyclopedia
⭐ Stars
Overview
A star is a self-gravitating ball of plasma that fuses light elements into heavier ones in its core, releasing the energy that lights the universe. The Sun is a completely average star — a G-type main-sequence dwarf about halfway through its 10-billion-year life.
Key facts
- •Nearest star (besides Sun): Proxima Centauri, 4.24 ly
- •Brightest in our sky: Sirius (magnitude -1.46)
- •Spectral classes: O, B, A, F, G, K, M (hot → cool)
- •Main sequence: hydrogen fusion phase
- •Endpoints: white dwarf, neutron star, or black hole
Why it matters
The Sun's cycles of activity — sunspots, flares, coronal mass ejections — are how our nearest star reaches out and touches Earth. Every solar storm we forecast is a stellar phenomenon happening 8 light-minutes away.
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Frequently asked questions
How many stars can I see with the naked eye?
From a truly dark site, about 4,500 stars are visible without any equipment. From a suburb, that drops to a few hundred; from a bright city, only a few dozen.
Is our Sun a big star?
No. The Sun is medium-sized — larger than 85% of stars in the Milky Way (most stars are cool red dwarfs), but tiny compared to red supergiants like Betelgeuse.
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