Eclipse basics
An eclipse happens when the Sun, Moon and Earth line up closely enough that one body blocks another. A solar eclipse occurs at new Moon and a lunar eclipse at full Moon, and only near the nodes.
What it is
The nodes are where the Moon's orbit crosses the ecliptic. An eclipse needs the Moon to be near a node at the time of new or full Moon, which is why eclipses occur only a few times a year.
How it is worked out or read
The site does not compute eclipses. The nodes Rahu and Ketu in the birth chart are the mean nodes, and they are the points that the classical texts link to eclipses.
Where it appears on this site
See mean and true nodes.
When eclipses can occur
An eclipse needs the Sun, Moon and Earth nearly aligned. A solar eclipse can occur only at new moon, when the Moon passes between the Sun and Earth, and a lunar eclipse only at full moon, when Earth's shadow falls on the Moon. The Moon must also be close to one of the nodes at that time, which is why eclipses happen only a few times a year.
The nodes and the classical view
The nodes Rahu and Ketu are the points where the Moon's orbit crosses the ecliptic, and the classical texts link eclipses with them. This site computes the nodes as mean points, and the chart's Rahu and Ketu are therefore not eclipse predictions.
Checking an eclipse
A reader who wants to know when an eclipse occurs should use a published astronomical table, not the Jyotish positions. The method of Jyotish is not designed to predict eclipses, and the site does not give eclipse times.
Watching an eclipse safely
Anyone who wishes to watch a solar eclipse should use proper eye protection, because looking at the Sun without it can damage the eyes permanently. Specially approved solar viewers or filters are needed for direct viewing, and a pinhole projector is a safe way to watch the Sun's image. These are practical points that matter far more than any traditional observance connected with the eclipse.
Lunar eclipses can be watched safely with the naked eye, since the Moon reflects the Sun's light, and they are often a pleasant event for families to observe together.
Eclipses and the calendar
Because eclipses occur only at new or full moon, they are naturally linked with the lunar calendar. Traditional rules sometimes give observances or restrictions around eclipses, and these vary between communities. A reader who follows such a rule should check the local tradition and the timings from a published astronomical source, since the Jyotish positions are not used to predict eclipse times on this site.
How often eclipses happen
Each year has at least two solar eclipses somewhere on Earth, and usually two or more lunar eclipses, though not every eclipse is visible from a given place. A lunar eclipse is seen from the whole night side of the Earth, which is why more people see lunar eclipses than solar ones.