After the formation of the Sun at the center of our Solar System, the planets<span> were formed from a protoplanetary disc. Whereas the terrestrial </span>planets<span> resulted from dust grains in the </span>inner<span> Solar System, </span>planets<span> in the </span>outer<span> Solar System accreted enough matter for their gravity to hold on to the nebula's leftover gas.</span>
Geologists have divided the earth history into time units that are largely based on the earth's biotic composition. The modern geological time scale includes both relative and absolute age dating and represents the most up-to-date assessment of the earth's history.
In the modern geological time scale, the eras in earth's history when the planet was populated with advanced life forms are referred to as the Paleozoic (meaning ancient life), the Mesozoic (meaning middle life), and the Cenozoic (meaning recent life).
<span>The main function of auxin is to help plants grow. Auxin stimulates plant cells to elongate, and the apical meristem of a plant is one of the main places that auxin is produced.</span>