Reading Astrology Apart from Astronomy: Aspects, the Saturn Return, Mercury Retrograde, the Lunar Nodes, Black Moon Lilith and Vedic Astrology
Behind common astrology terms like Mercury retrograde, the Saturn return and the lunar nodes are real astronomical events. This guide separates what actually happens in the sky from what astrology adds, alongside the studies that have tested astrology.
Last reviewed 2026-09-29
Facts in the sky, interpretations on the ground
Most astrology terms start from real astronomical phenomena. Linking those phenomena to personality or fortune, however, is an interpretive tradition. Separating the two lets you talk about astrology more clearly, whether or not you believe in it. This guide sums up six common concepts in two lines each: “what happens in the sky” and “what astrology makes of it.”
Aspects: angles between planets
- In the sky: the angle two planets make along the ecliptic as seen from Earth.
- In astrology: since Ptolemy’s Tetrabiblos in the 2nd century, 0° (conjunction), 60° (sextile), 90° (square), 120° (trine) and 180° (opposition) have been treated as the main angles, read as the tendencies two planets symbolise supporting or clashing with each other.
Describing a chart as “a conversation between the voices inside you” is a style of reading that spread with 20th-century psychological astrology.
The Saturn return: a cycle of about 29.5 years
- In the sky: Saturn takes about 29.5 years to orbit the Sun, so it returns to where it was at your birth around ages 29–30 and 58–59.
- In astrology: this period is read as a “life test” of facing responsibility and reality.
Interestingly, developmental psychology also describes the late twenties as a time when big career and relationship decisions cluster. But there is no evidence that Saturn’s position explains it; the social life course explains similar tasks at similar ages well enough.
Mercury retrograde: it only looks like it goes backwards
- In the sky: three or four times a year, for about three weeks, Mercury appears to move backwards across the sky. It is an apparent motion caused by differences in the orbital speeds and positions of Earth and Mercury; Mercury does not actually reverse.
- In astrology: a period prone to problems with communication, contracts, devices and travel.
“My messages got mixed up because Mercury is retrograde” can be a fun joke, but there is no statistical evidence that accidents or misunderstandings increase during these periods. If anything, confirmation bias is easily at work: we remember retrograde when something goes wrong and forget everyday mishaps.
The lunar nodes: where eclipses happen
- In the sky: the two points where the Moon’s orbit crosses the Sun’s apparent path (the ecliptic). Solar and lunar eclipses occur when the Sun and Moon are near these points. The nodes circle the ecliptic about every 18.6 years.
- In astrology: called the North and South Nodes in the West and Rahu and Ketu in Indian astrology, they are read as life direction or lessons carried over from the past.
Black Moon Lilith: not a body but a calculated point
- In the sky: a virtual point calculated from the farthest point of the Moon’s orbit from Earth (apogee). It is not a visible celestial body.
- In astrology: it began to be used in the 20th century as a symbol of suppressed desire or shadow.
It is often presented as an ancient tradition, but it helps to know it is a relatively recent addition.
Vedic and Western astrology: two zodiacs
- In the sky: because of precession — a wobble of Earth’s axis over roughly 26,000 years — the equinox point slowly shifts against the constellations.
- In astrology: most Western astrology uses the tropical zodiac, tied to the seasons (the equinox), while Indian Vedic astrology (Jyotisha) uses the sidereal zodiac, tied to the actual stars. The two are now about 24° apart, so the same birthday can fall almost a whole sign apart (Pingree, 1981).
Studies that have tested astrology
Scientists have tested astrology’s predictions directly. In Carlson’s double-blind experiment, published in Nature in 1985, astrologers asked to match birth charts to the correct one of three personality profiles did no better than chance. A study that followed thousands of “time twins” born minutes apart also found no tendency for their personalities or life outcomes to resemble each other (Dean & Kelly, 2003).
That is why astrology is safest used as a symbolic language rather than a predictive tool. If a chart’s symbols prompt you to ask useful questions about yourself, that is the value astrology can offer.
Summary at a glance
| Concept | What actually happens in the sky | Astrological reading |
|---|---|---|
| Aspects | Apparent angles between planets | Tendencies cooperating or clashing |
| Saturn return | Orbital period of about 29.5 years | A life test |
| Mercury retrograde | Apparent backward motion from orbital differences | Communication and device trouble (no evidence) |
| Lunar nodes | Where the Moon’s orbit crosses the ecliptic; eclipse points | Life direction; Rahu and Ketu |
| Black Moon Lilith | Calculated point of lunar apogee | Shadow (20th-century reading) |
| Vedic vs Western | Precession puts the two zodiacs about 24° apart | Same birthday, different sign |
You can calculate your Sun, Moon and Ascendant in OIYO’s natal chart. Please treat the results as symbols for fun and reflection.
References
- Ptolemy. Tetrabiblos (2nd century).
- Campion, N. (2009). A History of Western Astrology (2 vols.). Continuum.
- Pingree, D. (1981). Jyotiḥśāstra: Astral and Mathematical Literature. Otto Harrassowitz.
- Carlson, S. (1985). A double-blind test of astrology. Nature, 318(6045), 419–425.
- Dean, G., & Kelly, I. W. (2003). Is astrology relevant to consciousness and psi? Journal of Consciousness Studies, 10(6–7), 175–198.