Welcome to Earth Science with Mr. Williams!

What is Earth Science – what will you be learning in here?? Earth science is the study of our planet, its changing systems, and its setting in the universe Earth science is dynamic, which means it changes As scientists refine their ideas or new technology is invented, new discoveries are made!

What is Earth Science The Earth science “tree” is basically composed of 4 main branches of learning Geology – the study of Earth’s structure (what it’s made of and how it changes) Meteorology – the study of the changing conditions in Earth’s atmosphere (we know it as weather and climate) Astronomy – the study of Earth’s motions and the dynamics of other objects in space Oceanography – the study of the oceans

The 4 main “spheres” of Earth Lithosphere (solid) – the rocks of Earth Hydrosphere (liquid) – all of Earth’s water – the oceans, lakes, rivers, streams, and groundwater Atmosphere (gas) – the thin layer of gases that surrounds our planet Biosphere – all of the life on Earth

OK, so what is Earth like? Is Earth flat? That is, if you take a ship out to sea and keep going will you….FALL off the planet? Is Earth perfectly round? How BIG exactly is this planet? How many plums does it take to make a plum pie? These are some questions that need answering!

Is Earth Flat?? Um…..NO!

Size and Shape of Earth Most models of Earth represent it as a perfect sphere Can you think of a common model or representation of Earth? (hint…there are a few in this room…) This is basically accurate, but in fact… Earth is an oblate spheroid! Earth bulges slightly at the equator and is flattened at the poles, a result of its rotation How do we know this??

GRAVITY!!

Size of Earth This can be proven by measuring the diameter of Earth The fact is, the diameter equatorially is different from the diameter pole to pole The circumference is different as well Equatorially: diameter is 12,756km and circumference is 40,076km Pole to pole: diameter is 12,714km and circumference is 40,008km

Shape of Earth How do we know that Earth is round, and not flat? 4 ways!! 1) Watching a ship as it sails away from a shore 2) Altitude of polaris in the sky changes with latitude in the N. hemisphere 3) Earth’s shadow on moon during an eclipse

1) Watching a Ship sail away from shore….

2) Altitude of Polaris

3) Earth’s shadow on Moon during Eclipse

But what is the best reason that we know Earth is not flat??

4) Satellite photos from space!!

Earth’s Spheres Revisited (From ESRT)

Atmosphere (From ESRT)