Sky science
Main Sequence
Direct answer
Main Sequence: The Main Sequence is the band of stars steadily fusing hydrogen in their cores on a Hertzsprung-Russell diagram.
It is the longest stable phase of most stars.
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At a glance
- Found in
- Astronomy & Skywatching
- Related
- Spectral Type, Hertzsprung-Russell Diagram, Protostar, Red Giant
It is the longest stable phase of most stars.
A scientific orientation to scale, light, or motion; the article supplies the precise definition.
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The story behind Main Sequence
The H-R diagram revealed that most nearby stars occupy a diagonal sequence.
A one-minute story
The Wandering Stars
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Why Main Sequence matters
A star’s mass largely determines its main-sequence temperature, luminosity, and lifetime.
How to read Main Sequence
Do not use main sequence as a synonym for ordinary or unchanging.
Main Sequence in practice: an example
The Sun is a middle-aged main-sequence star powered by core hydrogen fusion.
Where readings of Main Sequence go wrong
Massive blue main-sequence stars have shorter lives than low-mass red ones.
Sources and editorial method
Research references used for this entry include:
- NASA Science: Stars - NASA overview of stellar birth, main-sequence evolution, giant phases, remnants, and supernovae.
- NASA Science: Universe Glossary - NASA definitions for common stellar, galactic, orbital, and high-energy astronomy terms.
- Source
- The Great Almanac Dictionary
- Category
- Astronomy & Skywatching
- Last updated
- 2026-09-26
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Common questions
What is the Main Sequence?
The Main Sequence is the band of stars steadily fusing hydrogen in their cores on a Hertzsprung-Russell diagram.
What do people get wrong about the Main Sequence?
Massive blue main-sequence stars have shorter lives than low-mass red ones.
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