Chapter 12

Chapter 12We can use space exploration to learn about stars, nebulae, and galaxies outside our solar system1Learning about SpaceOur current understanding of the solar system has changed with improved technologies

Theories are based on evidence that are collected remotely

2Early ideas..100 years ago, you would have been told that things never change in space

New evidence has caused scientists to rethink existing theories.

Between 1918 and 1929 more powerful telescopes were developed and more celestial bodies were seen

3Theories related to galaxy and universeEdwin Hubble: The first astronomer to identify other galaxies besides the milky way.

Galaxy: a collection of stars, planets, gas and dust held together by gravity

He noticed that all of the galaxies he was observing were moving away from each other

He proposed that the universe is expanding in all direction

Universe: The huge space which contains all of the matter and energy in existence.

4Explaining the Early UniverseBig Bang Theory: Theory about the origin and evolution of the universeSuggests that because of the evidence we have for an expanding universe, the universe must have been more compact at an earlier time. They traced the paths backwards.Estimate that the present matter in the universe was compressed together into a hot, dense mass 13.7 billion years ago.This matter began to move outward after a massive explosion

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Representation of the Big BangPlace colored, hole punched pieces in a balloon.

Blow up the balloon and then pop it with a needle.

The energy will expand the pieces.

Student activityhttp://educ.queensu.ca/~science/main/concept/gen/g06/G06LALB1.htm7Another theory to consider.Oscillating Theory: Suggest that the universe will expand to a certain point in time

Then will contract, due to forces of gravitation among the stars and galaxies

Scientists believe this will result in a big crunch followed by another Big Bang8

Like a bungee jumper: when they jump they accelerate due to gravity but eventually the force of the bungee will pull the jumper back.Theories related to the formation of our solar systemSolar System: The sun together with the eight planets and all other celestial bodies that orbit the sun

Nebular Hypothesis: the sun and the planets formed when a large nebula condensed and collected together by gravity

Nebulae: In between the stars in a galaxy, there are clouds of hydrogen gas and dust called Nebulae.

If material in these clouds can be pulled together stars can form

When a star forms its hot core remains surrounded by gas and dust and this leftover material can collapse and further collisions with other materials can occur eventually making a planet (see page 442)

10Theories related to the formation of our solar systemStellar Collision Theory: a theory that suggests that our Sun and the planets were created from collisions between stars.

The Nubular Hypothesis is believed to be more likely from observation of other star systems.

11Unit to measure large distancesLight year: The distance that light, which moves at 300 000 km/s, travels in a year; equals 9.5 trillion Km.

Light Year is a unit of measurement for extremely large distances. It is not a unit of time but a unit of distance

12The light from the moon takes 1.3 seconds to reach us so you are seeing the moon as it was 1.3 seconds ago.

The light from Jupiter takes 41 minutes to reach us, so you see Jupiter as it was 41 minutes ago.

When you look at objects far away in space, you are looking back in time

Astronomical UnitMeasurement equal to the average distance between the sun and earthApprox 150 million km

15Major Parts of the UniverseNebulae: clouds of dust and gas

16Major Parts of the UniverseGalaxy: forms when gravity causes a large, slowly spinning cloud of gases, dust and stars to contract. All the stars in the universe were formed in galaxies.

17Types of galaxies:Elliptical Galaxies: a galaxy that ranges in shape from a perfect sphere to an elongated but flattened ellipse and contains some of the oldest star in the universe.

Spiral galaxies: a shape for a galaxy with many long arms spiraling out from a center core made up of stars that formed long ago

19Major Parts of the UniverseBlack Holes: a large sphere of incredibly tightly packed material with an extraordinary amount of gravitational pull created when a star collapses into itself. It is called a black hole because nothing, not even light, can escape the powerful gravitational field.Forms from a star 25 times the size of the sun

20Quasars: A region of extremely high electromagnetic energy that develops as the super massive black hole in the center of a galaxy attracts more matter into itself.

Major parts of the UniverseStar: an object in space made up of hot gases, with a core that is like a thermonuclear reactor. There are giant and dwarf stars.

Dwarf Star: low mass stars that start small and stay that way most of their life. Burn hydrogen fuel slowly and have long life

Giant Star: Those stars that have the mass of the sun or greater. Burn hydrogen fuel faster and have a shorter life.

22Birth of a StarBegins to form from the materials in a nebulaGravity pulls together chunks of gas and dustAs gravity pulls the mass grows, materials collapses on itself and contracts, now called a protostar (early star)Collects more mass, temperature of the core becomes very hot and atoms fuse together to form larger atomsHydrogen atoms combine to from helium and this process called nuclear fusion creates a lot of energy and it is released and the star glows.23Stages in the Formation of a star

24Life Cycle of Stars (3 paths possible)

25Life cycle of a starThere are three possible paths:1) Low mass stars:Start small and exist as cool red dwarfs for most of their lives. They burn very slowly, can last for 100 billion yearsCan change into very hot, but small, dim white dwarfs and quietly burn out.

26Life cycle of starsPath 2) Intermediate mass stars: Stars about the same size as the sun burn their hydrogen fuel faster, typical life is 10 billion years.After a long time they expand into a red giantGradually sheds most of its materialCollapses in on itself becoming a white dwarf, Then cools more and turns into a black dwarf, a dense dark body made up of mostly carbon and oxygen27Life cycle of starsPath 3) High mass stars:Stars with a mass 12 or more times the mass of the sun burn fuel really fast and become a red giantAfter using all the fuel it becomes a supergiantThen a massive explosion to get a supernova It can then collapse to give a black hole or a neutron star

28Comparing StarsActivity: Using a similar worksheet shown on the next slide, research one of the stars. You will compare your star to the sun so you need all the same information about the sun. In the section other information find the magnitude of the star .

VegaCanopusSunArcturusBetelgeuseRigelDelta Orionis

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The PDF version of this Worksheet is attached30Comparison of Celestial BodiesWebsite: http://www.videosift.com/video/Planets-and-Stars-animated-size-comparison

31Science/Technology careers in Canada that are associated with Space explorationAstronautsScientists astronomers, physicistsEngineers electrical Doctors PilotsTechnicians - lens makersComputer programmer

32Scientific/Societal benefits and/or consequences of space explorationConsider each viewpoint

Medical: Astronauts experience bone density loss. Help to study Osteoporosis

Industrial: great deal of technology invented for space exploration is being used everyday. Ex. Cold weather clothing

33Agricultural: freeze dried food was invented for space travel but has spilled over in everyday life

Meteorological: View hurricanes, storms from space to help study them

Military: Observation of other countries

BrainstormWhat are the risks associated with space exploration and travel?

35Equipment failure, deathLeaving space junk, which can cause problems with future travel or satellites due to collisionsAstronauts are subjected to radiation from the Sun