Chapter 1: Looking at the Earth Section 2: The Earth in Space Glencoe McGraw-Hill The World & Its People Chapter 1: Looking at the Earth Section 2: The Earth in Space

1.2 The Earth in Space Section Objectives Identify what makes up the solar system. Describe how Earth moves in space. Explain why Earth’s seasons change.

I. The Solar System

I. The Solar System The solar system is made up of the sun, Earth, 7 other planets, & thousands of smaller bodies (moons, comets, & asteroids.) The planets & smaller bodies revolve around the sun.

The Solar System

I. The Solar System A planet follows an elliptical path around the sun. This is known as its orbit.

I. The Solar System There are 2 types of planets-those solid & small like Earth, & those that resemble balls of gas like Jupiter.

I. The Solar System Earth is surrounded by a layer of air called the atmosphere. Nitrogen & oxygen make up about 99% of this layer. http://www.tecnozono.com/english/earth%27s_atmosphere.htm

Atmosphere http://destinationofmarvel.blogspot.com/2011/01/atmosphere.html

I. The Solar System Earth makes 2 motions in space. It spins on an imaginary link (axis) that runs through the center of Earth between the North & South Poles. It takes 24 hours for Earth to complete 1 spin on this axis.

http://academic.brooklyn.cuny.edu/geology/leveson/core/linksa/direct.html

I. The Solar System F. The other motion is its complete orbit around the sun, or revolution. This revolution takes 365 ¼ days, which accounts for our need for a leap year once every 4 years.

II. The Sun & the Seasons

II. The Sun & the Seasons Earth is tilted 23 ½ degrees on its axis. Because of this, we have seasons as Earth rotates around the sun. http://www.planetseed.com/node/18122

II. The Sun & the Seasons The day in which the Northern Hemisphere receives the most amount of sunlight is the summer solstice. On this day, the sun is directly over the Tropic of Cancer.

II. The Sun & the Seasons The day in which the Northern Hemisphere receives the least amount of sunlight is the winter solstice. On this day, the sun is directly over the Tropic of Capricorn.

II. The Sun & the Seasons The 2 days each year in which the sun is directly over the Equator are known as the equinoxes. Both hemispheres receive the same amount of sunlight on these days.