Space

Part One

The Origin and Evolution of the Universe

What do we know about space?

• What is it?• Where is it?• What’s in it?• Is everything important?

1.1 What’s Important?

Gravity

• An attractive force that pulls things together

Why don’t people on the other side of the earth fall into space?• Because they are attracted towards the centre

of the earth by gravity• Any two objects with mass experience a

gravitational attraction towards each other

Top Five

Complete the Top Five assignment with a partner!• Found on Mr. Birrell’s website

http://mrbirrell.wikispaces.com

Planets

• From Greek meaning “wandering star”• Smaller than stars and do not emit light• Two types:

– Large, low-denisty gas giants– Smaller, rocky terrestials

• First confirmed discovery of a planet outside of our solar system came in 1995

Planets in our solar system

http://www.aerospaceweb.org/question/astronomy/solar-system/planets.jpg

Mars Surface

Mar Sunset VideoNasa.gov

Stars

• Start as huge clouds of dust and gas called “nebulas”

• As the clumps swirl and bump into each other, they get larger, and their gravitational force gets stronger

• Eventually the clumps are dense and hot enough for nuclear fission to start– Now called a star

Nasa.gov

Types to know:

• Red Giant– The size of our sun or smaller

• Red Supergiant– 10 times or more larger than our sun

• White Dwarf– After a star is dying, it shrinks in size and becomes

hotter

Other terms:

• Supernova– An enormous explosion at the end of a star’s life– Star has used up its fuels to keep nuclear fission

going– Core collapses to become either a neutron star or

a black hole– Shock waves cause the outer layers to explode

outward in a rapidly expanding nebula– Only one has been seen with the naked eye

Planetary Systems

• A group of objects including at least one planet orbiting around a star

• Our solar system is an example

Galaxies

• Made up of billions of stars, planetary systems, gas and dust, held together by gravity.

• The galaxy that our solar system is located is called the Milky Way Galaxy. If you could travel at the speed of light, you could travel from one side of the Milky Way Galaxy to the other side in 100,000 years.

Andromeda (our nearest neighbour)

Humans vs. Galaxies

What is the greater number: the number of cells in your body or the number of stars in a galaxy?

Typical galaxy: ~400 billion (400000000000)Cells in body: ~75 trillion (75000000000000)Largest galaxy known: ~100 trillion

Clusters of Galaxies

• Groups of galaxies held together by their mutual gravitational force

• Largest known gravitational bound objects• Typically contain 50 to 1000 galaxies• The Milky Way is in a cluster of about 40

galaxies

Galaxy Cluster ACO 3341

The Universe

• Everything that exists, including matter and energy everywhere

1.2 Space is Big

How big is it?

Really BIG

Question: How long would you survive if you were ejected into outer space?

Powers of Ten

Scales of very large things and very small things are tough to visualize.

“Powers of Ten” by IBM helps.

Special Heliocentric Illustration Tissue Demonstration

Quick, to the hallway!

Scientific Notation

• Scientific notation is a method of writing numbers that can make large or smaller numbers easier to read.

• Nobody wants to write 24000000000000000000 km over and over again.– This is the distance from Earth to the nearest

nieghbour galaxy

Rules for Writing in Scientific Notation

1. Write down all the significant numbers2. Put a decimal after the first number. (the number

will now be between 1-10)3. Write “x 10”4. Write the power corresponding to the number of

places the decimal was (would have) been moved. (Moving right is negative, moving left is positive)

• Count the number of digits between where the decimal was before and where it is now

25 000 000 000 000

1.Write down all the significant numbers

25

2.Put a decimal after the first number. (the number will now be between 1-10)

.

3.Write “x 10”

x 10

4.Write the power corresponding to the number of places the decimal was (would have) been moved. (Moving right is negative, moving left is positive)

13

Write 3.42 x 108 in standard notation.

Work in reverse!As the exponent is positive, we move the decimal to the right as many times as the exponent says to.

3.42 x 108 = 342000000

How long would it take…

Formula to find how long it takes to get somewhere:

Ex. How long to travel 550 km going 80 km/h?

MAKE SURE YOUR UNITS AGREE!

1.3 Where Did The Universe Come From?

• We don’t really know, but have a theory.

Flavour of the day:

THE BIG BANG!

What is The Big Bang Theory?

You Tell Me!

The Big Bang

• Observations of galaxies by Hubble and other astronomers in the 1920s show that the distant galaxies are all moving away from us at high speeds proportional to their distances.

• According to the Doppler Effect, this means that the universe is expanding.

• To be precise, it is space that is expanding, and carrying the galaxies along as it expands.

• Therefore, the galaxies appear to be moving away from each other.

• The galaxies themselves are not moving through space.

• Think of the “balloon analogy”

• If space is expanding, then it is larger now than it was.

• What would the Universe look like as you go back in time? What would it look like at half its age? A quarter?

• If the universe is constantly expanding, this leads to the conclusion that some time in the distant past, the universe was so small that it was just a point.

• This is the beginning of the universe, termed the “Big Bang”.

• Again, think of it not as an explosion, but a rapid expansion, such as blowing up a balloon.

Balloon Analogy Activity

• The two dimensional surface of the balloon will be used as an analogy for the three dimensional volume of space.

• Draw two dots about a thumb’s width on the surface of the balloon. Note the seperation.

• Partially blow up the balloon and again note the seperation of the dots.

• Watch the dots as your partner finishes blowing up the balloon.

Balloon Analogy Questions

• What happened to the dots as you blew up the balloon?– The separation increased

• What was moving: the dots, or the surface of the balloon?– The surface of the balloon expanded and carried

the dots with it as it moved through expansion

Balloon Analogy Questions

• What would an ant living on the surface of the balloon see? Would they see a center or an edge to their universe?– They would just see a surface with no center or

edge

• Observations are accumulating to show that the Big Bang happened about 13 billion year ago, therefore, this is also the age of the universe as we know it.

• The Big Bang theory is the best theory of the origin of the universe we have at this time because several observations support it.

• First, if this theory were true, we would expect that in the distant past the universe, being small and dense, would be very hot. As the universe (i.e., space itself) expands, it will cool. The signature of this cooling has been observed in detail by the COBE satellite in the early 1990s.

• Second, astronomers know that the element Helium makes up about one quarter of the matter in the universe. Indeed, the Big Bang theory predicts that Helium is produced during the Big Bang, by exactly the right amount.

1.4 Evolution of the Universe

Classification of Galaxies

• Examine the following image.• How would you classify the galaxies pictures?

Hubble Classification of Galaxies

• The best known and often used Hubble Classification was devised by Edwin Hubble.

• It splits galaxies into ellipticals, spirals, and irregulars.

Elliptical Galaxies

• has a smooth, featureless appearance• Ellipsoidal (not quite circular) shape• Among the largest of galaxies• Thought to have formed from collisions and

mergers between spiral galaxies

Elliptical Galaxy M87

Dwarf Elliptical Galaxy M110

Spiral Galaxies

• Flattened disc with a bulge and luminous spiral arms

• Diameter is 10,000 to 300,000 light years• Only exist if the galaxy is above a certain size• Our Milky Way Galaxy is a large spiral galaxy

Spiral galaxy NGC 1232

Spiral Galaxy M81

Irregular Galaxies

• Poorly defined structure that doesn’t fall into the other categories

• Only about 3% of observed galaxies fall into this category

• May have once been regular galaxies but were deformed by gravitational pull

• In the early universe, there were many more irregular galaxies– This suggests that galaxies used to collide far more

often

Irregular galaxy NGC 1427A

Magellanic Clouds ― Irregular Dwarf Galaxies

Hubble Deep Field Assignment

• Nelson Case Study 15.6– Complete letters a – h– Complete Understanding Concepts #s 1-3

Part Two

The Solar System

2.1 Characteristics of the Solar System

Assignment!

Characteristics to Know

• The sun comprises 99.8% of the total mass of the solar system.

• All other components, including the planets and their moons, asteroids, and comets makeup only 0.2% of the mass.

• In ascending order of the average distance from the sun, the planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune

(Distances not to scale)

• Planets, with their moons in tow, revolve around the sun in nearly circular orbits.

• The largest deviations from circular orbits are the orbits of Mercury and Pluto.

• Planets orbit the sun on nearly the same plane. That is, if one were to look at the solar system on the side, it will look like a very flat disk.

• Planets revolve around the Sun in the same direction (counter-clockwise when viewed from the top, or north, of the solar system).

• The planets may be classified into two groups with very different properties.

• The inner planets, up to and including Mars, are called Terrestrial Planets.

• The outer planets, from Jupiter to Neptune, are called Gas Giants.

• The terrestrial planets are mainly made of rock and metal; the gas giants are mainly made of gases.

Relative Sizes of Terrestrial Planets and Select Moons

• An asteroid belt resides roughly between Mars and Jupiter.

• Asteroids are large chunks of irregularly shaped rock, left over from the formation of the solar system.

2.2 Formation of The Solar System

• The study of the formation of the solar system is an interesting example of how science progresses, because it is in its early development, and many details are still not understood.

• The chosen theory must explain the previously discussed characteristics of the solar system.

Current Accepted Theory

• The Evolution Theory aka the Nebula Solar Theory

• Suggests that the solar system formed from the contraction of an interstellar dust cloud.

• As the gases in the disk cool, they begin to condense into solids (ices and dust grains).

• The dust grains collide with and stick to each other and form progressively larger chunks.

• Over a few hundred thousand years, a few of these larger chunks grew still larger into the planets. Around them, similar process formed their moons.

• Closer to the sun, temperature is very high, therefore the ices evaporated, leaving the inner planets the rocky worlds that they are today.

• Further out from the sun, temperature is cooler, the gravity of the planets there are able to incorporate ices to become the planets’ atmosphere.

• These are the gaseous planets.

Asteroids

• How do you explain asteroids?– Rocky remnants of solar system formation

• Another theory of the formation of the solar system, now discredited, is called the Catastrophe Theory.

• It proposed that the solar system was formed in an unusual event such as the collision of the Sun with another star.

• Problem with this theory is that it predicts that solar systems are too rare– Scientists have discovered over 100 solar systems

thus far

Blue Spots: Results of Collisions Between Stars