Every five and a half months, when the Sun is near one of the moon's nodes, eclipses can occur. New moons become dramatic solar eclipses, when the Moon comes between the Earth and the Sun and blots out the Sun's light. Full moons become lunar eclipses, where the Moon is obscured by the Earth's shadow.
Eclipses are about change, sometimes radical change.
For people that have grown happy with the status quo, changes can be quite unwelcome, even uncomfortable. This is perhaps the reason eclipses have gotten such a bad reputation over the years, since they tend to disrupt situations in our lives that we'd rather keep intact. In my experience, if you concentrate on these shifts as a normal part of your growth process, leaving behind outmoded behaviors, the results are usually positive. Also, eclipses are stronger and more long lasting in their effects than normal new or full moons. Become aware of the themes and events entering your life at these times, since you will likely be working on these themes for quite some time.