Solar eclipse: astronomical explanation and symbolic reading

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What is a solar eclipse?

A solar eclipse occurs when the Moon passes exactly between Earth and the Sun. It always happens at new moon, when the illuminated face of the Moon is turned toward the Sun and we see only its dark side. The Moon then casts its shadow onto a small area of Earth, from which the Sun can be seen partly or wholly hidden.

It is a remarkable coincidence: the Sun is about 400 times wider than the Moon and about 400 times farther away. Seen from Earth, the two bodies therefore have roughly the same apparent size (half a degree), which makes total eclipses possible. This coincidence is only temporary on the scale of geological time: the Moon is moving away from Earth at about 3.8 centimetres per year.

Why not at every new moon?

The Moon's orbit is inclined about 5.1 degrees to the plane of Earth's orbit around the Sun. Most of the time, the Moon therefore passes slightly above or below the alignment. An eclipse occurs only if the new moon happens near one of the two points where the lunar orbit crosses that plane, the lunar nodes (see the lunar nodes). These moments recur about every six months (every 173 days): these are the eclipse seasons, each lasting a little over a month. A solar eclipse and a lunar eclipse often occur about two weeks apart (see the lunar eclipse).

The four types of solar eclipse

Type	What is seen	Why
Total	The Sun is entirely hidden; daylight turns to twilight; the solar corona can be seen	The Moon looks slightly larger than the Sun (it is closer to Earth)
Annular	A ring of light surrounds the dark Moon	The Moon is near its farthest point and looks slightly smaller than the Sun
Hybrid	Annular on one side of the path, total on the other	Earth's curvature changes the appearance along the track; this is rare
Partial	Only part of the Sun is hidden	The observer is off the central axis, or the shadow passes beside Earth

Totality never lasts more than 7 minutes 32 seconds, and most often between two and three minutes. The band where it is visible is less than 270 kilometres wide. One can therefore wait centuries to see a total eclipse from the same place (on average between 360 and 410 years). The last total eclipse visible in metropolitan France was on 11 August 1999.

Watching without damaging your eyes

Looking at the Sun without protection can cause permanent damage to the retina, without any pain at the time. A few safe rules:

• Use certified eclipse glasses (standard ISO 12312-2), new or in good condition, without scratches or holes, bought from a reputable supplier.
• Ordinary sunglasses, smoked glass, X-rays and CDs do not protect your eyes.
• Never point binoculars, a telescope, a camera or a phone at the Sun without a suitable solar filter fitted to the front of the instrument.
• Only the totality phase, within the band of totality, can be watched with the naked eye. As soon as the Sun reappears, put your glasses back on.
• Stay beside children. Projecting an image of the Sun through a small hole (a pinhole, a colander, foliage) is an indirect and safe method: you look at the image on the ground or on a card, not at the Sun.

If you feel visual discomfort after an observation, see an ophthalmologist without delay.

A little history

The Mesopotamians recorded eclipses for a very long time and discovered an 18-year cycle of recurrence, called the saros: after 6,585.3 days (18 years and 11 days), an almost identical eclipse recurs, shifted by about a third of a turn to the west. Eclipses were read as omens concerning the king (the Enūma Anu Enlil series); a “substitute king” ritual is also recorded. A famous account credits the Greek Thales with predicting an eclipse in 585 BCE, but this date and the prediction itself are debated.

In China, court astronomers recorded eclipses for the emperor. In many cultures, people told of a monster devouring the Sun (the demon Rahu in India, a dragon in China). Today, these eclipses are calculated with great precision for centuries ahead, which does not diminish their beauty.

What the astrological tradition reads into it

In astrology, a solar eclipse is like an amplified new moon. The new moon evokes the beginning of a cycle; the solar eclipse would be an emphatic version of it: a threshold, a turning point, an interruption of routine. Astrologers look at the sign and the degree where it occurs and compare them with the planets of a birth chart. Ptolemy, in the 2nd century, spoke of it mainly as a sign concerning peoples or countries.

• Beginning: a page turns, a theme opens.
• Shadow: what is hidden or poorly seen becomes more apparent.
• Duration: a modern rule says the effect lasts about six months; this is a convention with no precise ancient source.

In all these readings, the point is an invitation to reflect, never a forecast of events.

What science does not confirm

No study shows any effect of an eclipse on health, mood or personal events. Old beliefs, such as those directed at pregnant women or at food during an eclipse, have no medical basis. An eclipse is a shadow phenomenon, predictable and harmless if one protects one's eyes.

Nuanced wording

Avoid	More nuanced
“This eclipse is going to upend your life.”	“Many astrologers see in it a symbol of a turning point; each person can read into it whatever speaks to them.”
“Do nothing during the eclipse.”	“The moment may simply invite us to observe the sky and take stock.”
“The eclipse is bad for sign X.”	“Tradition links the event to a theme of the sign; this remains an interpretation.”

Questions for reflection

1. Which cycle of my life is ending, and which is beginning?
2. What am I failing to see, or not wanting to see, for lack of light?
3. If I took five minutes to look at the sky, what would I want to note down?
4. What would a small first step look like, without waiting for a sign from the sky?

Going further

Astrology is a symbolic tradition with no scientific validation: these pointers are aids to reflection, never forecasts, and they do not replace a full birth chart. See also eclipses and the axis of the nodes, the astronomical guide to eclipses and the new moon.

Frequently asked questions

Also read

The meanings mentioned belong to tradition and symbolism. They are neither promises of results nor medical advice. Back to In-depth astrology.