Book excerpt: Planets, Sunspots and Earthquakes presents a working hypothesis of how planets trigger sunspots and earthquakes. Two distinct and separate effects are considered: one is an internal effect whereby the core of the sun and the earth become more active. The other is an external effect whereby the combined effect from external bodies stresses the earth's crust at a point where it enters or leaves the gravitational field of the group of external bodies.The causes of the initial internal processes that are necessary for the final seismic trigger effect to operate are examined and the connection with sunspot cycles is explored. The work is the result of observation and investigation during three eleven-year sunspot cycles, and offers material for further research by specialists and students.