Read each slide then use the red or some underlined words to complete the organizer.

Did it start as a bang!

The Expanding Universe A. The Big Bang Theory: Idea that all matter began in an infinitely small point and exploded out in all directions

Billions of stars, dust, and gas held Galaxies: _____________________ _____________________________ ______________________________ Billions of stars, dust, and gas held together by gravity

Galaxy: Billions of stars, dust and gas held together by gravity Let’s start out big and work our way down Universe Virgo super cluster Local group Galaxy: Billions of stars, dust and gas held together by gravity

ALL space and everything that is in it. Universe ALL space and everything that is in it.

Supercluster Virgo

decided to classify them by the way they looked into 3 types Who knew? ________________ was an astronomer in the 1920s who gathered many pictures of galaxies noticed they all didn’t look alike decided to classify them by the way they looked into 3 types “E” or _____________________ “S” or _____________________ “SB” or ____________________ Spiral Barred Spiral

Galaxies Three types of galaxies: Galaxies are grouped together in clusters. The cluster the Milky Way belongs to is called the Local Group. Three types of galaxies: Cluster of galaxies

Three types of galaxies: Irregular Spiral Elliptical The Hubble Tuning Fork

Where do we live? Earth’s Galaxy—and Others Galaxies are grouped together in clusters. The cluster the Milky Way belongs to is called the Local Group. Cluster of galaxies

Spiral Galaxies Arms are made up of stars and dust Spiral Galaxies: Circular galaxies that have arms curve outward from a central hub. Arms are made up of stars and dust Two spiral galaxies!!

Illustration/draw and label:

halo disk bulge Spiral Galaxy

Elliptical Galaxies -Contain mostly older and dimmer stars. Most common type of galaxy; large three-dimensional football shaped galaxies. -Contain mostly older and dimmer stars. Vary in shape from completely round to extremely elongated ovals. Unlike spiral galaxies No bright nucleus at their center. Elliptical galaxies are represented by the letter E Divided into seven subgroups according to their shape. These subgroups are labeled E0 to E7. E0 galaxies nearly circular in shape while E7 galaxies are extremely elongated or stretched out.

Illustrate / Draw Elliptical

Irregular Galaxies Come in many different shapes and are smaller and less common Irregular Galaxies - No regular shape, includes nebulas, with no central bulge or spiral arms.

Illustrate/ Draw:

Earth’s Galaxy Galaxy: A large group of stars, gas, and dust held together by gravity. Milky Way: Our galaxy which contains about 200 billion stars and many nebulas Spiral Galaxies

The Milky Way Galaxy The Milky Way is the galaxy that contains our Solar System which is just one of the several galaxies of the universe. . This name derives from its appearance as a dim "milky" glowing band arching across the night sky, in which the naked eye cannot distinguish individual stars. 100,000 light years in diameter Our sun orbits the center of the galaxy once every 240 million years A barred spiral galaxy Contains over 200 billion stars Its where we live!!!!!

Solar System Our star (Sun), the planets, many moons, and other small bodies that ALL travel around the Sun

Solar System

What do we see in the sky? The stars move in the sky but not with respect to each other The planets (or “wanderers”) move differently from stars They move with respect to the stars They exhibit strange retrograde motion What does all this mean? How can we explain these movements? What does the universe look like?

The Great Debate! Heraclides (330 B.C.) developed the first Solar System model, beginning of the geocentric versus heliocentric debate

Timeline Galileo 1564-1642 Newton 1642-1727 Tycho 1546-1601 Copernicus 1473-1543 Kepler 1571-1630

Geocentric (Ptolemaic) System The theory (in Greek, geo means earth), which maintained that Earth was the center of the universe, usually referring to the system of Claudius Ptolemy.

Geocentric (Ptolemaic) System The accepted model for 1400 years The earth is at the center The Sun, stars, and planets on their spheres revolve around the earth: explains daily movement

Geocentric (Ptolemaic) System cont’… To account for unusual planetary motion epicycles were introduced Fit the Greek model of heavenly perfection – spheres are the perfect shape, circular the perfect motion

Illustrate/ Draw model: Select only one to illustrate

Heliocentric (Copernican) System The word "helios" in Greek means "sun." Heliocentric means that the sun is at the center. A heliocentric system is one in which the planets revolve around a fixed sun. Sun cented is what we believe today

Helio- continued Thus Mercury, Venus, the Earth, Mars, Jupiter and Saturn all revolve around the sun. The moon is the only celestial sphere in this system which revolves around the earth, and, together with it, around the sun.