Earth temperatures tend to fall as Mercury and Venus in turn pass around on the opposite side of the Sun, and to rise as each of these planets comes into the same heliocentric longitude as the earth.

Sunspot maxima visible to the earth tend to occur more often when Mercury (the only planet studied in this respect) is on the opposite side of the Sun, while sunspot minima are more frequent with Mercury on the same side as the earth.

Earth temperatures show a pronounced tendency to be above normal during falling or low phases of the 11-year sunspot cycles, and to be subnormal in the rising or high phases of these cycles.

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