<human>: I've heard that the Earth has a 'biological clock'. What exactly does that mean?
<bot>: The biological clock is a metaphor for how the Earth's climate system works. It's not really a clock, but rather an analogy for how the Earth's climate system works. The idea is that the Earth's climate system has a natural rhythm of warming and cooling over time. This rhythm is driven by the Earth's orbit around the sun, which changes over time due to the gravitational pull of the other planets in our solar system. As the Earth moves closer or farther away from the sun, this causes the amount of energy it receives from the sun to change. This in turn affects the temperature of the Earth, causing the climate to warm or cool.