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NOTES
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Origin and Age of the Universe
The Universe means everything that exists everywhere.
All the space, matter, and energy that is, was, or ever will exist.
April 2002 issue of Discover Magazine
Student Notes: To Print out the Notes,
Extra Credit: The Galaxy Song!
Practice it here!
Labs:
Exposing the Sun!
Ellipse Relationships
Our Celestial Sphere
Standards: Key Idea 1: The Earth and celestial phenomena can be described by principles of relative motion and perspective.
Major Understandings:
1.2a The universe is vast and estimated to be over ten billion years old. The current theory is that the universe was created from an explosion called the Big Bang. Evidence for this theory includes:
- cosmic background radiation
- a red-shift (the Doppler effect) in the light from very distant galaxies.
1.2b Stars form when gravity causes clouds of molecules to contract until nuclear fusion of light elements into heavier ones occurs. Fusion releases great amounts of energy over millions of years.
- The stars differ from each other in size, temperature, and age
- Our Sun is a medium-sized star within a spiral galaxy of stars known as the Milky Way.
- Our galaxy contains billions of stars, and the universe contains billions of such galaxies.
1.2c Our solar system formed about five billion years ago from a giant cloud of gas and debris. Gravity caused Earth and the other planets to become layered according to density differences in their materials.
1.1b Nine planets move around the Sun in nearly circular orbits.
The orbit of each planet is an ellipse with the Sun located at one of the foci.
In order to study the stars we must know more about the properties of light.
- Form of electromagnetic radiation
- Energy that moves like both a wave and particle (photon)
- Can travel through outer space (vacuum)
- Speed: 300,000 km/second, 186,000 miles/second
- Small part of the Electromagnetic Spectrum
- A light-year is the distance light can travel in one year.
- If the speed of light is 186,000 miles per second (300,000 km per second), then calculate the distance that light will travel in one year.
- 186,000 miles/second x 60 seconds/min x 60 min/hour x 24 hours/day x 365 days/yr =
| Light Year Conversion Table |
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Kilometers
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9,460,800,000,000 |
| Miles |
5,865,696,000,000 |
| Light year |
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Using a light year as a distance measurement has another advantage -- it helps you determine age. Let's say that a star is 1 million light years away. The light from that star has traveled at the speed of light to reach us. Therefore, it has taken the star's light 1 million years to get here, and the light we are seeing was created 1 million years ago. So the star we are seeing is really how the star looked a million years ago, not how it looks today. In the same way, our sun is 8 or so light minutes away. If the sun were to suddenly explode right now, we wouldn't know about it for eight minutes because that is how long it would take for the light of the explosion to get here.
Did you know that when you look at objects in the night sky, you’re looking back in time? How far back you see depends on how long it’s taken light from that object to reach you. The farther the object, the farther back in time you see.
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Light from the moon—which is very, very close in space—takes about 1.3 seconds to travel to Earth. So you see the moon as it looked just over a second ago! |
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The sun is much further; its rays take about eight minutes to reach Earth. |
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Saturn is an average of 10 times farther from the sun than Earth.
We see Saturn as it was about 80 minutes ago. |
| Once you look beyond our solar system, objects are so far away it takes more than hours or even days for light to reach us. We’re seeing objects as they looked years ago. Look at the images below and find out how far back in time your looking. |
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Proxima Centauri: Our Nearest Star is 4.2 Light Years away.
The light you see from Proxima Centuri today left the star when you were in 5th grade! |
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Sirius: Brightest Star in the sky is 8.6 Light Years away
When you find the brightest star in the sky the light you see left Sirius when you just got out of kindergarten! |
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Pleiades: Cluster of new stars found in the constellation of Taurus
"The Seven Sisters": 400 light years away from us. At this time Shakespeare was writing his plays in England (1600 A.D.) |
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Orion Nebula: Where stars are born is 1,500 Light Years away. The light from Orion left when the Roman Empire was falling (500 A.D.) |
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Crab Nebula: Supernova of an Exploding Star: 6,000 light years away from us. The light that we see today left when the first written records of history began over 6,000 years ago. |
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Andromeda Galaxy: Neighbor Galaxy, 2.2 million light years away. The light we see today left the Andromeda Galaxy before humans exited on the earth! |
All of the objects above are relatively very close to us.
Lets get an idea of the true depth of the Universe! http://hubble.stsci.edu
Hubble's longest exposures are like a core sample of the universe, recording galaxies at many different distances. This is one of the deepest core samples ever taken. The objects are distant galaxies, over 13 billion light-years away. (Source: APOD).
Looking Deep: These are not stars but Galaxies each containing over 100 Billion Stars!
They are about 13 Billion Light Years Away from us!
I wonder what they look now?
How long would we have to wait to know this answer?
The universe is thought to be about 14 Billion years old!
Read all about it!
- Timeline of the Universe
NASA Origins Project - An excellent description of early time and the formation of the Universe.
Formation of the Universe
- Big Bang: about 14 Billion years ago
- Element formation in stars
- Planetary System Formation
- Forming Earth-like Planets
- Forming Jupiter-like Planets
- Chemistry of Life
The Big Bang Theory
Imagine the Universe in a year!
- Everything started out in a small area
- Giant explosion sent everything expanding out in all directions
- Matter clumped together forming galaxies, stars, planets
- Universe is still expanding
- Rate of expansion is increasing
Evidence for the Big Bang
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| Galaxies moving towards us shift toward blue in color. |
Almost all galaxies have a red shift indicating that the universe is expanding. |
Galaxies moving away from us shift toward red in color. |
| Also, the farther the galaxy is away from us the greater the red shift showing the rate of expansion is increasing. http://archive.ncsa.uiuc.edu/Cyberia/Bima/doppler.html |
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Most all of these Galaxies are over 10 billion light years away and have a red shift in their spectra. This means that we are looking at galaxies 10 billion years old that are moving away from us very, very quickly. What the look like now and how far away they are at this moment is anyone's guess. |
Galaxies: View different types of galaxies!
- Collection of billions of stars, gas and dust
- Average galaxy has over 100 billion stars
- There are over 100 billion galaxies in the universe
- Three types: Spiral, Elliptical, and Irregular
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Our closest spiral Galaxy is named Andromeda. It is a large spiral galaxy. It is about 2.3 million light years from Earth and contains about 400 billion stars.
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what is the name of our Galaxy?
How do you think it got its name?
Milky Way as seen in infrared (heat) waves.
What type of Galaxy is our galaxy?
Milky Way Facts:
- Width = 100,000 light years across
- Our Sun is 30,000 light years from the center of the galaxy
- Sun orbits the Milky Way every 200 million years
- Has over 200 billion stars
- Only one of the billions of galaxies in the Universe
How many planets could be in our Galaxy?
Lets make a simple equation. Our sun has nine planets. It is assumed now that most stars have planets. Let us take a low average and imagine that each star only has 5 planets. Since our Milky Way Galaxy has about 200 Billion stars how many planets would that be using our example?
5 x 200 Billion = 1 Trillion possible planets in only our Galaxy!
So how many is one Trillion? Lets imagine a trillion pennies?
If we have 100 Billion Galaxies in the Universe and we use this example that each star has about 5 planets how many possible planets are there in the Universe?
Saying the average galaxy is the size of the Milky Way and has 200 Billion stars and each with 5 planets giving us 1 Trillion possible planets in our galaxy alone.
If you multiply 1 trillion planets per galaxy times the estimated 100 Billion galaxies how many possible planets do you get?
1 Trillion x 100 Billion = ?
100,000,000,000,000,000,000,000
Estimated possible planets in the Universe!
100,000 quintillion possible planets!
See 1 quintillion pennies!
Now imagine 100,000 of these quintillion sized cubes. This will give you a rough idea about the number of planets possible in the universe!
Check out really big numbers here!
What about the possibility of life?
The Drake Equation was developed by Frank Drake in 1961 as a way to focus on the factors which determine how many intelligent, communicating civilizations there are in our galaxy.
Drake's Equation: Nc = N* fp ne fl fi fc fL
- N* represents the number of stars in the Milky Way Galaxy
- fp is the fraction of stars that have planets around them
- ne number of planets per star that are capable of sustaining life
- fl is the fraction of planets in ne where life evolves
- fi is the fraction of fl where intelligent life evolves
- fc is the fraction of fi that communicate
- fL is fraction of the planet's life during which the communicating civilizations may survive
When all of these variables are multiplied, we get:
- Nc, the number of communicating civilizations in the galaxy.
Try Drake's Equation for yourself!
The great void in interstellar communication is not space, but time.
In this animated presentation, learn how the lifetime of a civilization affects its ability to communicate.
Stars
The Solar System:
 
Extra-Solar Visions!: Explore other possible worlds
- Our solar system began forming about 5 billion years ago as gas clouds collapse into planets and a star.
- Contains: planets, moons, comets, asteroids, and the sun
- Planets orbits are elliptical (oval shaped) around the sun
- Even though they are elliptical they are nearly circular
- Ancient times people believed in the Geocentric model:
Earth centered model of the solar system
- Now we know that the Heliocentric model: Sun centered model of the solar system is true. Nine Planets: http://www.seds.org/
- View our Planets on a journey away from the Sun!
Evidence for other Planets!
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Many stars are thought to have planets because the planets gravity makes their star wobble in space! |
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Some planets have been found to block starlight as they orbit their sun. Brain Pop: Solar System!
Pale Blue Dot: http:www.space.com/ |
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Kepler's Laws of Planetary Motion
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1. The age of the universe is measured in 10-20
- a. thousands of years
- b. millions of years
- c. billions of years
- d. trillions of years
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2. Which statement best describes how galaxies generally move?
- a. galaxies move toward one another
- b. galaxies move away from one another
- c. galaxies move randomly
- d. galaxies do not move
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3. Background radiation detected in space is believed to be evidence that
- a. the universe began with an explosion
- b. the universe is contracting
- c. all matter in the universe is stationary
- d. galaxies are evenly spaced throughout the universe
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4. The great system of 200 billion stars to which the sun and our solar system belong is the
- a. Andromeda Galaxy
- b. Large magellanic Galaxy
- c. Milky Way Galaxy
- d. Orion Nebula Galaxy
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5. A star differs from a planet in that a star
- a. has a fixed orbit
- b. is self-luminous
- c. revolves about the sun
- d. shines by reflected light
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6. As a star color changes from blue to red, the surface temperature of the star
- a. decreases
- b. increases
- c. remains the same
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7. The sun is best described as a
- a. very large star
- b. medium-sized star
- c. red star
- d. cool star
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8. Which type of star is associated with the last stage in the evolutionary development of most stars?
- a. main sequence star
- b. supergiant
- c. giant
- d. white dwarf
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9. Which is not included in our solar system?
- a. Polaris
- b. the moon
- c. meteors
- d. asteroids
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10. Today it is most commonly believed that our solar system formed
- a. by gravitational collapse of a gas-dust "cloud"
- b. from material exploded form the sun
- c. at the time of the Big Bang that formed the present universe
- d. by fusion of matter between the sun and a passing star
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