Knowledge
Glossary
The terms that appear in the calculation and in the interface are explained in plain words. The glossary does not replace the sections on planets, signs, houses and aspects: it is here so you do not stumble over words as you read.
Terms in the glossary: 21
Chart basics
- Natal chart
- Positions of bodies at the moment of birth projected onto the zodiac circle. Calculated using date, time and location coordinates.
- Ecliptic
- Plane of Earth's orbit. Planet positions are measured by longitude along it—from zero to 360 degrees.
- Ephemerides
- Tables of celestial body positions for specific times. The platform takes them from the NASA JPL DE440 core, not from pre‑compiled collections.
- Ascendant
- Point of the ecliptic rising above the horizon at birth. Marks the boundary of the first house and depends on time to the minute.
- Midheaven
- Highest point of the ecliptic at birth, the boundary of the tenth house. Denoted as MC.
- House
- One of the twelve sectors of the chart, representing an area of life: the first – how a person is seen, the seventh – partnership. The house boundaries depend on the time and place of birth, so without a known time the houses are not constructed.
- House system
- The rule by which the chart is divided into houses. MIRA calculates using Placidus, and beyond the polar circle, where this method loses meaning, switches to Porphyry and indicates which system is applied.
Time and place
- UTC
- Coordinated universal time to which the birth moment is converted. Calculations are performed in it, not in local time.
- Historical offset
- Difference between local time and UTC that applied on the birth date. For Moscow on 12 April 1991 it was plus three hours, not the current value: the country cancelled and introduced time changes.
- Rectification
- Refining an unknown birth time using life events. Provides a time estimate, not a fact, and is always marked as an estimate.
Movement
- Retrograde motion
- Apparent backward movement of a planet through the zodiac as seen from Earth. The planet itself does not turn; this is due to speed differences.
- Transit
- Aspect of a planet in the current sky to a point in the natal chart. Answers what is happening now, not who the person is.
- Return
- Moment when a planet returns to the same longitude as at birth. Sun return – birthday, Saturn return – around 29 years.
- Ingress
- The planet's transition into the next sign or house.
- Solar return
- A chart for the moment when the Sun returns to the natal degree. Cast once a year, around the birthday, and describes the themes of the coming year.
- Void-of-course Moon
- A period when the Moon no longer forms aspects until it moves into the next sign. Initiatives started during this time usually do not continue, so important tasks are avoided then.
Connections
- Aspect
- The angle between two points on the chart, belonging to the list of significant ones: 0, 60, 90, 120, 180 degrees and a few minor ones.
- Orb
- The allowable deviation from the exact aspect angle. The smaller the deviation, the stronger the aspect.
- Synastry
- Comparison of two charts: aspects between the planets of one person and the planets of another.
- Composite
- A separate chart of a couple, constructed from the midpoints between the same planets of the two charts.
- Applying aspect
- An aspect whose deviation from the exact angle is decreasing: the theme gains strength. For a diverging aspect the opposite – the peak has already passed.