Earth Science for midterm

• earth it resembles, the blue, cloud-envelope lapis lazuli gem planet that we recognize immediately from satellite pictures that seems remarkably stable
• Continents and oceans

  • Encircled by an oxygen-rich atmosphere
  • Support familiar life-forms
• Earth and its atmosphere are continuously altered.
• Plate tectonics shift the continents, raise mountains and move the ocean floor while processes not fully understood alter the climate.
• Such constant change has characterized Earth since its beginning some 4.5 billion years ago.
• heat and gravity shaped the evolution of the planet.
• Exploring this past offers us the only possibility of understanding the origin of life and, perhaps, its future.
• Scientists used to believe the rocky planets, including Earth, Mercury, Venus and Mars, were created by the rapid gravitational collapse of a dust cloud, a deation giving rise to a dense orb.

  •In the 1960s the Apollo space program changed

  this view.
• The Russian geophysicist had suggested in 1944 that planets grew in size gradually, step by step.
• •

  According to Schmidt, cosmic dust lumped together to form particulates, particulates became gravel, gravel became small balls, then big balls, then tiny planets, or planetesimals, and, nally, dust became the size of the moon.
• Inter stellar dust hypothesis of Otto Schmidt. The earth and the solar system have taken to have been formed from gas and dust particles.
• The Earth is made up of four distinct yet connected spheres – lithosphere, hydrosphere, atmosphere and biosphere
• The lithosphere (or geosphere) describes all the rocks, minerals and molten magma found on or in the Earth
• The hydrosphere describes all the water on Earth – including liquid water (oceans, etc.) and vapour (precipitation)
• The atmosphere describes the layer of gases surrounding the Earth and is divided into sections (stratosphere, etc.)
• The biosphere is composed of all the living organisms on the planet (including plants, animals, bacteria, etc.)
• The four spheres are interconnected, so human impact on one sphere will potentially effect other spheres
• Lithosphere. The boulders of Mount Everest, the sand of Miami Beach and the lava erupting from Hawaii's Mount Kilauea are all components of the lithosphere.
• The actual thickness of the lithosphere varies considerably and can range from roughly 40 km to 280 km. • The lithosphere ends at the point when the minerals in the earth's crust begin to demonstrate viscous and fluid behaviors
• The exact depth at which this happens depends on the chemical composition of the earth, and the heat and pressure acting upon the material.
• The lithosphere is divided into 15 tectonic plates that fit together around the earth like a jagged puzzle: • African, Antarctic, Arabian, Australian, Caribbean, Cocos, Eurasian, Indian, Juan de Fuca, Nazca, North American, Pacific, Philippine, Scotia and South American.
• • These plates aren't fixed; they're slowly moving. • The friction created when these tectonic plates push against one another causes earthquakes, volcanoes and the formation of mountains and ocean trenches.
• Atmosphere • made of the layers of gases surrounding a planet or other celestial body.
• •Earth's atmosphere is composed of about 78% nitrogen, 21% oxygen, and one percent other gases.
• Layer of atmosphere

  • exosphere
  • thermosphere
  • mesosphere
  • stratosphere
  • troposphere
• •A hydrosphere is the total amount of water on a planet. •The hydrosphere includes water that is on the surface of the planet, underground, and in the air
• • A planet's hydrosphere can be liquid, vapor, or ice. •On Earth, liquid water exists on the surface in the form of oceans, lakes, and rivers
• biosphere is made up of the parts of Earth where life exists—all ecosystems.
• •The biosphere extends from the deepest root systems of trees, to the dark environments of ocean trenches, to lush rain forests, high mountaintops, and transition zones like this one, where ocean and terrestrial ecosystems