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

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

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

Review of the Solar System

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…)

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

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

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.

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!

Resources http://www.bobthealien.co.uk/earthlife.htm