Earth as a Habitable Planet

What do you think are the characteristics of the planet Earth that make it different from all the other planets?

What are the major requirements for a star to support life on its planet?

What are the minor requirements for Earth to support life?

What is the significance of the presence of liquid water on Earth?

What temperature range is life limited to on Earth?

Why is free oxygen in the atmosphere important for life?

How does adequate sunlight contribute to life on Earth?

What is the impact of toxic substances in the atmosphere on life?

What are the effects of lethal radiation on life?

What nutrients are necessary for building and maintaining an organism's body?