Sky science
Right Ascension Hour
Direct answer
Right Ascension Hour: A Right Ascension Hour is 15 angular degrees along the celestial equator, with 24 hours spanning a full circle.
One right-ascension hour equals 15 degrees.
$0 today, then $12/month after 7 days. Cancel anytime.
At a glance
- Found in
- Astronomy & Skywatching
- Related
- Ecliptic Coordinate System, Galactic Coordinate System, Declination Circle, Celestial Meridian
One right-ascension hour equals 15 degrees.
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 Right Ascension Hour
Hour notation became practical for star catalogues and transit observations.
A one-minute story
The Wandering Stars
How the moving planets were watched, named and found, and what a transit is.
Why Right Ascension Hour matters
Right Ascension Hour connects the celestial grid with Earth’s daily rotation and sidereal time.
How to read Right Ascension Hour
Read right ascension as angular time, not elapsed civil time.
Right Ascension Hour in practice: an example
Six hours of right ascension corresponds to 90 degrees around the equator.
Where readings of Right Ascension Hour go wrong
Minutes and seconds of right ascension are angular subdivisions, not ordinary clock durations.
Sources and editorial method
Research references used for this entry include:
- U.S. Naval Observatory: Astronomical Almanac Glossary - Definitions for astronomical coordinates, time, reference systems, and observable phenomena.
- International Astronomical Union: Standards of Fundamental Astronomy - IAU-maintained standards and algorithms for astronomical reference systems and coordinate transformations.
- Source
- The Great Almanac Dictionary
- Category
- Astronomy & Skywatching
- Last updated
- 2026-09-26
Convert sky hours into degrees
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
- Star Hopping
- Zenith
- Astronomical Opposition
- Celestial Pole
- Exit Pupil
- Irregular Galaxy
- Objective Lens
- Position Angle
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 a Right Ascension Hour?
A Right Ascension Hour is 15 angular degrees along the celestial equator, with 24 hours spanning a full circle.
What do people get wrong about a Right Ascension Hour?
Minutes and seconds of right ascension are angular subdivisions, not ordinary clock durations.
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.
