An eclipse happens when the Sun, Earth, and Moon line up closely enough for one body to block light. In a solar eclipse the Moon passes in front of the Sun and covers part or all of its disc, which can only happen at a New Moon. In a lunar eclipse the Full Moon passes through Earth’s shadow. Solar eclipses can be total, annular, or partial; lunar eclipses can be total, partial, or penumbral, the last being a faint dimming that is easy to miss.
Most New and Full Moons pass without an eclipse, because the Moon’s orbit is tilted against the ecliptic. An eclipse needs the lunation to fall near a lunar node, where the Moon’s path crosses the Sun’s. That alignment comes around in eclipse seasons roughly six months apart, and every calendar year has between four and seven eclipses.
The astrology calendars do not list eclipses, because whether you can see one depends on where you are. The eclipse visibility tool searches the next five years for a place you choose. For solar eclipses it gives local contact times and how much of the Sun is covered; for lunar eclipses it shows whether the Moon is above your horizon. Never look at the Sun without correctly rated solar protection.
The New and Full Moons behind every eclipse are explained in Moon phase and the guide to reading a Moon calendar.
In a chart
A solar eclipse is a New Moon, a conjunction of the Sun and the Moon, that falls a few degrees from a node. A lunar eclipse is a Full Moon, an opposition, close to the nodal axis. Astrologers often note the degree of an eclipse and check whether it lies near a planet or angle in a birth chart. That habit is an interpretive tradition. The eclipse’s visibility, on the other hand, is pure geometry: a lunar eclipse can be seen wherever the Moon is above the horizon, while a solar eclipse is visible only along a limited part of Earth.
Where you see it on Astrologican
These free tools and pages calculate or list it, so you can see it in a real result.