1. How does life on Earth exist?
Objective:
7.9 Earth and space. The student knows components of our solar system. The student is expected to:
(A)  analyze the characteristics of objects in our solar system that allow life to exist such as the proximity of the Sun, presence of water, and composition of the atmosphere

2. Well, What is a Living Thing?
There are six characteristics of living things. Living things:
Are made up of cells
Use energy
Are able to reproduce
Have a specific genetic code
Are able to adapt to their environment
Maintain homeostasis, which is an internal steady state

3. What are Living Things Made of?
Living things are made of organic compounds.
C – carbon
O – Oxygen
N – Nitrogen
S – Sulfur

4. Review of the Solar System

5. The Sun
The distance between Earth and the Sun is ideal: about 150 million kilometers (93 million miles)
Gives the perfect amount of:
Light
Heat
Allows life to be created and supported on Earth
Distance allows the rest of the conditions we will talk about to exist on Earth (ex. atmosphere, water, etc…)

6. Light Photosynthesis for plants
Plants convert carbon dioxide, water, and light into sugars, with simultaneous release of oxygen (a poison to plants, but helpful to us!).
Plants grow towards light
The length of our day is long enough for plants to get enough sunlight for photosynthesis

7. Water Earth has water! Essential to life as we know it
Contains Oxygen
Doesn’t contain poisonous elements
Is drinkable
Allows molecules to move around easily
Because of Earth’s distance from the sun, water exists in solid, liquid, and gaseous forms

8. Atmosphere
Mostly composed of oxygen, nitrogen, carbon dioxide and hydrogen
Composition: 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide.
Oxygen is required by most creatures on Earth even though it is not the most plentiful in the atmosphere.
Plants constantly pull out poisonous carbon dioxide and replace it with oxygen in the atmosphere.
The pull of gravity keeps Earth’s atmosphere on the planet
It is thick enough to block most of the rays of poisonous radiation
*Talk about how even .039% Carbon dioxide is a lot when put into perspective*
Luckily, Earth’s carbon cycle prevents too much poisonous carbon dioxide from collecting in Earth’s atmosphere. Carbon Dioxide makes up most of Venus and Mars.
Mercury is too small to keep an atmosphere and Mars atmosphere is very, very thin.

9. Climate
Climate is influenced by the amount of carbon dioxide in the atmosphere
Pressure fluctuations in the air and water, ocean currents, and geological/volcanic forces also influence climate.
Even with all these competing factors, the temperature on Earth does not go between extreme measurements
For example, Mercury’s temperature can range from -200 degrees Celsius to 375 degrees Celsius!

10. Resources