Unit 6: Universe

Lesson 2

The Expanding Universe • Today, most scientist think the universe began

as a huge explosion, or ________, about ___ billion years ago. This explosion sent matter and energy traveling through space. The big bang theory states that _____________________________________.

big bang 15

the universe has been expanding ever since.

• Proof that the universe is expanding is in the color of the ______ that ______ give off. Light from a moving object changes color, just like sound from a passing car has a higher pitch when the car moves toward you and a lower pitch when it moves away. The color change depends on whether the object is moving ___________ or _______. By observing light from distant objects, scientists can tell what _________ the object is moving from Earth.

light stars

toward away

direction

• When a distant object moves _______ from Earth, its color shifts toward the ______ of the spectrum. Scientists have observed light waves from ______________ and found that light from all galaxies is shifted toward the _______ of the spectrum. The greater this red shift is, the _______ away the object is. This red shift tells scientists that galaxies are _____________from Earth and that the universe is ___________.

awayred end

distant galaxies

red endfarther

moving awayexpanding

The Universe• The universe contains billions of stars grouped

in galaxies.• Energy, matter and empty space make up the

universe.• Scientists use powerful telescopes to study it.

Hubble Space Telescope

The Milky Way Galaxy• Our Solar System is part of The Milky Way

Galaxy.– A galaxy is a huge groupingof stars (billions)

• Shaped like a flat pinwheel called a spiral galaxy

How Big is the Universe?

Our Solar System

Polaris

http://www.lpi.usra.edu/education/skytellers/polaris/about.shtml

• Called the North Star• Not an extremely bright star but it seems to stay in the same place.• Located straight over the North Pole• Located in the Little Dipper’s tail or handle.• Sailors still use Polaris for celestial navigation, and modern astronomers often use Polaris to help them align their telescopes

Can you find Polaris??

The revolving Earth is similar to a spun umbrella. Since our axis points to the North Star, that star remains nearly stationery in the sky while all the other stars describe circles around it. Illustration: Bob King

How to Find Polaris

• http://www.onr.navy.mil/focus/spacesciences/observingsky/constellations3.htm

Polaris and Latitude• http://www.onr.navy.mil/focus/spacesciences/observingsky/constellations4.htm

Used to determine the latitude of a ship at sea by measuring the altitude of the Sun or star, the mariner's Astrolabe was popular in the late 15th and

early 16th Centuries.

latitude = Angular distance north or south of the equator