The Night Sky, Explainedby Dmitry Shteynbuk
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How stars workDefinedTerm

Main sequence

The diagonal band on the HR diagram where stars spend most of their lives fusing hydrogen.

The Sun sits about halfway along it.

Used in these guides

  • How a Star Is BornHow stars work
  • The HR Diagram: The Single Most Useful Chart in AstronomyHow stars work
  • How Stars Die: White Dwarfs, Neutron Stars, and Black HolesHow stars work
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The Night Sky, Explained — by Dmitry Shteynbuk, Miami, Florida

© 2026 Dmitry Shteynbuk

This is an astronomy site, not an astrology site. If you're looking for horoscopes or zodiac readings, see the explainer on the difference.