Ch 30 con’t.

Black Holesblack hole an object so massive and dense

that even light cannot escape its gravitySome massive stars produce leftovers too

massive to become a stable neutron star. These stars contract, and the force of the

contratction leaves a black hole.

Black HolesHow do we know they are there if they are

invisible??

It is observed by its effect on a companion star. Matter from the companion star is sucked into the

black hole by its gravity….just before the matter is absorbed, it swirls around the black hole.

The gas gets so hot that X rays are released. This is how astronomers detect them.

http://www.space.com/common/media/video/player.php?videoRef=black_holes

ConstellationsBecause of the tremendous distance from which

the stars are viewed, they appear fixed in their patterns.

For more than 3000 years, people have observed and recorded these patterns.

Such patterns of stars and the region of space around them are called constellations.

http://www.youtube.com/watch?v=mDObFetwDishttp://www.youtube.com/watch?v=qwbnjq3ntrU

Galaxygalaxy a collection of stars, dust, and gas

bound together by gravityGalaxies are the major building blocks of the

universe. Astronomers estimate that the universe contains hundreds of billions of galaxies.

GalaxyWhat is the name of our galaxy???

Milky Way!!

A typical galaxy, such as the Milky Way, has a diameter of bout 100,000 light-years and may contain more than 200 billion stars.

Types of GalaxiesGalaxies are classified by shape into three

main types.A spiral galaxy has a nucleus of bright stars

and flattened arms that spiral around the nucleus.

Elliptical galaxies have various shapes and are extremely bright in the center and do not have spiral arms.

An irregular galaxy has no particular shape, and is fairly rich in dust and gas.

Spiral Galaxy

Elliptical Galaxy

Irregular Galaxy

The Milky WayWhat type of galaxy is our Milky Way??

A. SpiralB. ellipticalC. irregular

A

Ok, so how did our Universe begin??There are plenty of theories…

Big Bang…Religious views…

Everyone is entitled to what they believe. Since no one was alive when it all “happened”, everything is based on theories. Lets see what the big bang theory is all about.

BANG!

Mr. HubbleEdwin Hubble went to Oxford University to study law.

He wasn’t happy as a lawyer and decided to return to his passion of studying space.

Hubble had also devised a classification system for the various galaxies he observed, sorting them by content, distance, shape, and brightness.

Hubble found that the spectra of galaxies, except for the few closest to Earth, were shifted toward the red end of the spectrum.If the were shifted toward the red end of the

spectrum, are the moving toward or away from the Earth??

AWAY!

The Expanding UniverseUsing Hubble’s observations, astronomers

have been able to determine that the universe is expanding.

The expanding universe can be thought of as a raisin cake rising in the oven. If you were able to sit on one raisin, you would see all the other raisins moving away from you.

Similarly, galaxies in the universe are moving farther away from each other due to the expansion

of the universe.

Big Bang Theorybig bang theory - the theory that all matter

and energy in the universe was compressed into an extremely small volume that 14 to 15 billion years ago exploded and began expanding in all directions

Cosmic Background Radiationcosmic background radiation - radiation

uniformly detected from every direction in space; considered a remnant of the big bang.

Astronomers believe that cosmic background radiation formed shortly after the big bang.

The background radiation has cooled after the big bang, and is now about 270°C below zero.

Cosmic Background Radiation

Ripples in SpaceMaps of cosmic background radiation over

the whole sky show ripples.These ripples are irregularities caused by

small fluctuations in the distribution of matter in the early universe, and may indicate the first stages in the formation of the universe’s first galaxies.

Dark MatterAnalysis of the ripples in the cosmic

background radiation shows that the matter that humans, the planets, the stars and the matter between the stars makes up only .4% of the universe.

About 23% of the universe is made up of a type of matter that does not give off light but that has gravity. This type of matter is called dark matter.

Dark EnergyMost of the universe is made up of an

unknown material called dark energyScientists think that dark energy acts as a

force that opposes gravity. Many scientists think that some form of undetectable dark energy is pushing galaxies apart.

POP QUIZ!!Take out a sheet of paper!

1. What is a galaxy?a. stars, dust, and gas bound together by

gravityb. debris, dirt, and trash bound together by

gravityc. air, gas, and rock in the universed. planets, moons, and stars bound together

by magnetism

2. What is important about Hubble’s discovery that there is a red shift in the spectra of galaxies?

a. It suggests that the universe is contracting.

b. It suggests that the universe is expanding.

c. It proves the big bang theory.d. It suggests the existence of black holes.

3. What is an irregular galaxy?a. a galaxy with no particular shapeb. a galaxy shaped like a stretched-out

footballc. a galaxy that has vast areas without

starsd. a galaxy that has high mass and is rich

in dust and gas

4. A spiral galaxy has a nucleus ofa. dim stars, and spiral arms consisting of

billions of young stars.b. bright stars, and spiral arms consisting of

billions of young stars.c. bright stars, and spiral arms consisting of

billions of old stars.d. dim stars, and spiral arms consisting of

billions of old stars.

5. Astronomers believe that cosmic background radiation formed

A. about a billion years ago.B. more that a trillion years ago.C. shortly after the big bang.D. shortly before the big bang.

6. The big bang occurred abouta. a billion years ago.b. 5 billion years ago.c. 14 million years ago.d. 14 billion years ago.

Bonus!7. A rapidly spinning neutron star that emits

bursts of radio and optical energy is aa. supernova.b. black hole.c. red giant.d. pulsar.