The purpose of this slide is to help students realize that sometimes we are asked to “learn” that is very hard to understand. Often we do not have the knowledge necessary to make it all “make sense.” That doesn’t mean that a scientist would have a hard time with it!
Astrophysicists are struggling with this right now.
This is the really really hard part to understand.
Of course you would not expect students to memorize “cosmic particle horizon” but it is such a cool term. Everything outside the horizon cannot be perceived by us.
Click on the picture and have your sound on to here the Doppler effect!
If you are connected to the server, click on the hyperlink for an explanation of red and blue shift.
Universe combo janelle
Warm Up – Page 200 What do you know about the universe?
Spotting scope - A small refractor to line up the big scope. Eyepiece for viewing Today’s reflector
Mount Palomar Observatory Hale Telescope Inside Mt. Palomar Observatory Large telescopes are put in observatories to protect them.
Other scopes at Palomar Look across the mountain tops!
Where should we put our telescopes? 1. Mountain tops above atmospheric haze. Reduces the twinkle effect and distortion. 2. Far from city lights ( light pollution). 3. If our atmosphere blocks the wavelength needed to study, then the scope goes into orbit!
Gamma Rays These telescopes are looking for high energy events: black holes, neutron stars and quasars. Due to their high energy content, Gamma rays are able to cause serious damage when absorbed by living cells. Gamma rays are also able to penetrate dense materials. Aren’t we glad our atmosphere blocks them!
The Compton Gamma Ray Observatory orbits the Earth, detecting high-energy photons – GAMMA RAYS
The spectroscope Takes light from stars and analyzes it.
Light from a star or other source goes through the slit.
Every element has a different set of spectrum lines. Much like people having different fingerprints.
So spectrum lines tell us what elements are in a star without going there!
Notice that emission and absorption are the same.
Warm Up – Page 200 <ul><li>Why are large Earth based telescopes placed on high mountain tops. </li></ul>
Major features of the Milky Way and the Universe
A constellation is a group of stars than appear to be together but are not. They seem to form a picture in the sky. People use them to find their way around the sky like someone using objects to get from place to place.
Orion the hunter The constellation looks flat but all the stars are at different distances from us.
Leo the Lion Cygnus the Swan Can you see the drawing ?
The Zodiac is a special group of constellations that extend out from Earth’s equator.
Astronomers want to know how far away stars are! From here on earth, they all look the same distance. In fact, ancient people thought they were all “stuck” on a glass sphere.
To measure the distances in space, astronomers use a light year. A light year is the DISTANCE light travels in one year. One light year is equal to a little under 6 trillion miles! (6,000,000,000,000) Proxima Centauri is the closest star to our solar system. It is about 4 light years away. Going the speed of light it would take us 4 years to get there. Traveling as fast as the average spaceship, it would take between 70,000 and 100,000 years to get there! Video clip on a light year
A galaxy is a large group of stars bound together by gravity.
There are three kinds of galaxies. Spiral Elliptical Irregular Video clip on galaxies
Some spiral galaxies Pictures by the Hubble Space Telescope
Notice the individual stars in the picture. They are not part of the galaxy in the picture but part of our own Milky Way Galaxy.
So why are they in the pictures? If you look out a window with wood trim, it is hard to get a view without them in the way. These stars are in our view as we are looking out of our galaxy!
Our Milky Way Galaxy is a spiral galaxy. We think! This is not really a picture of our galaxy – just one that looks like what we think our galaxy is like!
Why not? If you were inside Lanier Middle and had never been out of the building your entire life, would you be able to know what the school looked like from a distance? Of course not. All you could do is look out the windows and get some view of part of the building. If you looked out enough windows you might get a general idea but you could never know for sure if you were right about all its features.
Top view Side view Video clip on our location in the galaxy
Milky Way using a “fish eye” lens Notice the comet In the night sky, a band of stars can be seen across the sky as a blurry image. When you see this, you are looking into the part of the galaxy with more stars. Our view of the Milky Way
Every star we see in the night sky is in our own galaxy. We cannot see stars in other galaxies because they are too far away. The Milky Way is estimated to have 200 billion stars.
Nebulas are often named by what they look like! Witch head nebula Veil nebula Horse head nebula They provide the material for new stars to form.
North American nebula Cat’s eye nebula ring nebula ant nebula
Current estimate of the age of the universe is 13.7 billion years. The solar system is 4.6 billion years old. The solar system is not the same age as the entire universe .
Hubble deep field Click on the picture and watch as the Hubble telescope zooms in to an area just above the Big Dipper!
Prove that the following wff is valid by means of resolution: xp(x)v xq(x) x p(x)vq(x) Why can’t you do this problem?
You cannot do these problems because you do not know the math between what you now know and what you would need to know to do the problem!
You will have the same problem with understanding the process that scientists call the big bang. Just because you cannot understand some of what scientists say about the big bang does not mean that scientists do not understand it clearly! They know the science between what you know and what is needed to be known to understand the big bang!
Think of crime scene investigations! Did the detectives see the explosion? No! They have to figure it out from evidence!
That is what astronomers do! They take evidence from space to figure out the science!
Edwin Hubble discovered that the universe is expanding.
If the Universe is expanding, at some time it must have been concentrated in a single point.
Some sort of “event” occurred to cause the change that formed the universe we have today.
"The Big Bang" This event is what scientists call the
Not like an explosion where debris flies off into space!
Instead, it was the expansion of space and time itself , and therefore occurred everywhere at the same time.
Any galaxies farther than ~ 13.7 billion ly away we cannot see! Why: because the light hasn’t had time to get here!!!
Are there galaxies beyond what we can see? Astronomers think that answer is yes. We just can’t see them.
What evidence do we have supporting the Big Bang?
is the evidence for this expansion. Universal red shift
Red shift is is a form of the Doppler Effect. Sound shows Doppler effect too! Clip on this picture to experience the Doppler effect.
red shift What you just heard was the Doppler effect with sound. Red shift is the Doppler effect with light.
Notice that the line groupings are the same – only shifted red .
From our position in the universe, it looks like we are the center because everything appears to be moving away from us. But we are not in the center.
As a balloon gets larger every point moves away from every other point.
If your galaxy was a raisin, notice that every raisin is moving away from every other raisin. In fact, a raisin far away from you is moving away faster than those that are closer. Our expanding universe acts the same way.
The second evidence is Cosmic Microwave Background Radiation!
This is energy “left over” from the Big Bang. -discovered in the early 1960’s.
This is like an oven that was used to make cookies. The cookies are not visible but the smell is there (evidence) and when you open the oven door there is just a little bit of heat still there (another piece of evidence).
What are the two pieces of evidence that support eh Big Bang Theory that we discussed? Video clip of the big bang