Sky science
Open Star Cluster
Direct answer
Open Star Cluster: An Open Star Cluster is a relatively young, loosely bound group of stars formed from the same molecular cloud.
It is a sparse stellar family in a galactic disk.
$0 today, then $12/month after 7 days. Cancel anytime.
At a glance
- Found in
- Astronomy & Skywatching
- Related
- Reflection Nebula, Dark Nebula, Globular Cluster, Spiral Galaxy
It is a sparse stellar family in a galactic disk.
A scientific orientation to scale, light, or motion; the article supplies the precise definition.
What does your own chart say about you?
Choose love, work or purpose. Your reading is written from your chart. Your reading uses your own birth details.
Walk through Alex’s whole example first
The Road of AgesSee the turning points of your whole life, from your birth date
See your road's shape
Prefer to explore first?
The Road of AgesThe turning points of your whole life, from your own chart
Walk my road
Free, by email
Your daily Almanac letter
One short letter at 7 each morning: the day’s theme read for your own chart, and one thing to do with it.
The story behind Open Star Cluster
Proper-motion and color-magnitude studies transformed visual groupings into physical membership lists.
A one-minute story
The Wandering Stars
How the moving planets were watched, named and found, and what a transit is.
Why Open Star Cluster matters
Shared age and composition make open clusters laboratories for stellar evolution.
Open Star Cluster in practice: an example
The Pleiades contains hot young stars embedded in a broader moving population.
Where readings of Open Star Cluster go wrong
Not every apparent star grouping is gravitationally or historically related.
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
Compare stars born together
A definition tells you what it is; your own birth chart tells you what it means for you. The Oracle casts your real chart and answers for your love, your work, and your year ahead, in conversation. It opens with the 7-day Seeker trial.
Speak with the OracleRelated terms
More in Astronomy & Skywatching
- Primary Mirror
- Secondary Mirror
- Stellar Parallax
- Active Galactic Nucleus
- Astronomical Spectroscopy
- Center of Mass Orbit
- Focal Ratio
- Keplerian Orbit
From the reference page to your own chart
Every word here
is in your own chart.
- A personal reading about love, work or purpose, written from your chart
- A practical next step to consider
- It opens with 7 days free, with the AI Oracle and daily guidance
$0 today, then $12/month after 7 days. Cancel anytime.
Common questions
What is an Open Star Cluster?
An Open Star Cluster is a relatively young, loosely bound group of stars formed from the same molecular cloud.
What do people get wrong about an Open Star Cluster?
Not every apparent star grouping is gravitationally or historically related.
Free, by email
The Almanac, in your inbox at 7
One short letter at 7 each morning: the day’s theme read for your own chart, and one thing to do with it.
