Eclipses occur roughly every 6 months or so, and we get 2-3 at a time. Eclipses can trigger events, and this can be beneficial or challenging depending on the aspects they're making and what else you have going on astrologically. The strongest eclipses are usually the ones that are in your Sun, Moon, or Rising sign.
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What is an eclipse?
Eclipses occur when a new or full moon occurs within 18 1/2 degrees of the Lunar Nodes, which are the points in the Moon's orbit where the Moon crosses the ecliptic. Solar eclipses occur with new moons and lunar eclipses occur with full moons.
We alternate between a new and full moon every 2 weeks or so, but we don't have eclipses every 2 weeks. Instead they occur every 6 months or so, and we get 2 or 3 at a time, 1-2 of each. Eclipses have stronger energy than new and full moons because of this, and they can act as a catalyst, triggering big events and developments in our lives.
Eclipses in your Sun, Moon, or Rising sign:
Eclipses that occur in your Sun, Moon, or Rising sign tend to be the strongest by themselves. The Sun is who you truly are, the Moon is your emotional self, your Rising is your outer self, so they are important parts of your natal chart and you can feel it strongly whenever they're getting hit.
Eclipses that occur conjunct (aligned with) your Sun, Moon, or Ascendant tend to be the strongest eclipses you experience, but this isn't really good or bad by itself. It's just strong energy. With a solar eclipse, it's tied to beginnings, and with a lunar eclipse, it's tied to endings and realizations. If it's joined by challenging aspects (conjunctions, squares, and oppositions) by transit (moving) Saturn, Uranus, Neptune, or Pluto, or some difficult progressions, this may be on the challenging side. This isn't bad per se, but it can be more challenging and you may be forced to deal with things that you haven't yet.
If it's joined by beneficial aspects (sextiles and trines) by those planets or Jupiter, or some beneficial progressions, this can be on the positive side. You may be better equipped to embark on the new beginnings with the solar eclipse, or make progress and recognize that with the lunar eclipse.
Suggested Reading: The New & Full Moons page for general interpretations in the houses & aspects