Chapter 12Space Exploration

Section 12.1 page 428Explaining the Early Universe

GALAXY – collection of stars, planets, gasand dust held together by gravity-Edwin Hubble was the first astronomer to identify other galaxies besidesthe milky way.

SOLARSYSTEM

GALAXY – Milky Way

UNIVERSE

Measuring Distances in Our Universe

• The distance to most stars from Earth are millions of AUs therefore:-distances within our Universe are measured in light

years1 light year = distance light will

travel in 1 year= 9.5 trillion km

Speed of light = 300, 000 km/s

Hubble’s Proposal

• Edwin Hubble noticed that galaxies were not staying still but they were moving away from each other (based on red shift analysis)

• He proposed that the Universe is expanding,

and galaxies are moving away

from each other• • The further away the Galaxy, the

faster it is moving

THEORIES OF THE ORIGIN OF THE UNIVERSE

THE BIG BANG THEORY

• Since there is evidence that our Universe is Expanding, it must have started somewhere!

• ~13.7 billion years ago there was a massive explosion and very high temperatures ~ 1 billion °C were reached

• Very Rapid Expansion of a tiny volume of space• Open Universe – one that will Expand

forever. First described by Georges Lemaitre in 1927.

THE OSCILLATING THEORY

• Closed Universe – one that will expand so far and is then drawn back by gravitational forces, all the matter will meet again in a “Big Crunch”– This theory says the Universe goes through a

series of bangs and crunches in an ongoing cycle

– Currently still expanding from the most recent explosion

THEORIES OF THE ORIGIN OF THE SOLAR SYSTEM

STELLAR COLLISION THEORY• This Theory says that Our Solar

System was created from the spin off of colliding stars!

NEBULAR HYPOTHESISNebulae(Nebula)- clouds of Hydrogen

gas and dust between stars- When pulled together by gravity, stars

form if hot enough- A nearby exploding star could have caused

a shock wave which started the process-As the cloud begins to collapse it starts to rotate

-4.5 billion years ago, the Sun became an active star and the leftover material combined to form 8 planets, and other smaller bodies such as moons, asteroids, and comets. -Not all the planets formed at the same time or in the same way…the inner planets were formed first followed by the outer planets

TASK

Read Section 12.1 in the textbook

and answer the following questions: p. 443 #s 1,5,6,7,8,9,11,12.

p. 433 1. Hubble noticed that all galaxies are moving away from each other.

2. Hubble proposed that the universe is expanding in all directions, and that the galaxies have taken the same amount of time to reach

their present positions from an original starting point.

4. The Oscillating theory states that the universe is closed and that there is enough matter in the universe to slow (because of gravity) and

eventually stop the expansion of the universe. According to this theory, all matter will meet again in a Big Crunch.

5. Cosmic background radiation is the radiation left over from the Big Bang expansion.

p. 439

1. The nebular hypothesis of solar system formation is that the Sun and planets formed when a large nebula condensed and was

collected together by gravity.

2. Our solar system formed more than 4.5 billion years ago.

3. Inner or terrestrial planets and outer or Jovian planets.

4. The distances are too great to be measured in astronomical units.

Section 12.2 Galaxies and Stars

SPIRAL ELLIPITICALOur Milky Way Galaxy, Earth is on a spiral arm, we see the center on it’s side at night

Some of the oldest and largest galaxies are elliptical, more then 50% of galaxies are this shape

What is a star?

Stars are hot bodies of glowing gas that vary in size, mass and temperature. The color of a star is determined by its temperature: the hottest stars are blue and the coolest stars are red.

THE EVOLUTION OF STARSDWARF STARS GIANT STARS

Small

Burn fuel slowly & last a long time (100 billion years)

Red dwarfs eventually change into very hot, but small, dim white dwarfs and burn out.

Large, burn fuel quickly, last a short time

RED GIANTS slowly shrink into a white dwarf which may cool into a black dwarf ORSUPER GIANTS (massive starts) collapse in a dramatic explosion called a supernova and eventually collapse to form aneutron star or a black hole

The Life of a Star

Stage 1 – stars are born in Nebula and condense into a large globule of gas and dust that contracts under its own gravity

Stage 2 – The condensing matter begins to heat up and glow forming Protostars.

Stage 3 – If there is enough matter the central temperature reaches 15 million degrees and nuclear reactions start.

Stage 4: The star begins to release energy causing it to shine.

The Death of a Star -When a star starts to run out of hydrogen fuel I it becomes a red giant or a super giant.

- Red giants grow bigger and form a cloud of gas called a planetary nebula. As it cools, it becomes a white dwarf which will eventually run out of fuel and die becoming a black dwarf.

-Red super giants may suddenly explode which is called a supernova. After this explosion, leftover star material may form a neutron star. After a large mass star explodes, a large amount of mass remains and the gravity of the mass is soo strong that the gas is pulled inward, decreasing its volume. Eventually, the gravity is soo strong that nothing can escape, including light. The massive star then becomes a black hole.

BLACK HOLE• Sphere of extremely dense

material with a gravitational pull so strong not even light can pass out of it!

• Created when a SUPER GIANT star collapses in on itself

QUASAR• Region of extremely high energy

which develops around a supermassive black hole as matter is attracted intoitself

• This energymakes them thebrightest objectsin the universe.

The Future of Space Exploration

Careers Related to

Space

Engineer

Astronaut

Doctor

Scientist

Pilots

Technicians