1. Part A: INTRO & Our Place in Space
The Traveling Exhibit
Alien Earths
Science Background
Part A: INTRO & Our Place in Space
This is Part A: INTRO and Our Place in Space of a 4-part Science Background presentation in support of the Alien Earths Traveling exhibit.
INTRO and Our Place in the Universe
Star & Planet Formation
Planet Quest
Search for Life and CONCLUSION
prepared by Dr. Cherilynn Morrow for the Space Science Institute Boulder, CO

2. The Questions Behind the Exhibit
Are we alone?
Where do stars and planets come from?
What would life elsewhere be like?

3. The Big Ideas
We are developing extraordinary new tools, techniques, and insights for exploring the age-old question of whether there is life beyond Earth.
Our search for habitable worlds and signs of life in our galaxy is guided by our study of how stars and planets form & our understanding of life on Earth.

4. The science background is organized by EXHIBIT AREA:
Welcome to the Exhibit
Alien Earths
Our Place in Space
The science background is organized by EXHIBIT AREA:
Our Place in Space (Powers of 10 display) straight back
Search for Life to the left
Star & Planet Formation to the right
Planet Quest Dome straight back

5. A. Our Place in Space KEY QUESTIONS:
What and where are we in the cosmos?
Could there be other planets like Earth out there?

6. 3. Stars and star systems orbit the centers of galaxies
Moons
orbit planets
4. Galaxies orbit each
other in clusters.
2. Planets orbit stars

7. Can You Fill in the Blanks?
Pre-Visit Activity
Alien Earths
Can You Fill in the Blanks?
Click for Answers
Exploring the Structure of the Universe
Before entering the exhibit, fill in the blanks using the following key words.
galaxy orbit solar system moon star Universe Earth Jupiter planets Sun
100 billion
The Sun is a _________ located at the center of our __________________. Our home, called __________, is one of 9 planets that orbit around the _________. Earth has one _________ that orbits around it each month, showing different phases. Some planets have many moons that ___________ around them. ________________ is the largest planet in the Solar System and has 64 moons! Our sun is one of about _______________ stars contained in the spiral _____________ we call the Milky Way. Astronomers are now discovering Jupiter-sized ____________ that orbit around some of those distant stars. Outer space is even bigger yet because the Milky Way is only one of an estimated 100 billion (100,000,000,000) galaxies in the ______________!
star
solar system
Earth
Sun
moon
orbit
Jupiter
100 billion
galaxy
planets
Universe
Astronomy Games: Fill-in-the-Blank Copyright Cherilynn Morrow – Used with permission

8. Our Place in the Solar System
Earth is one of 9 PLANETS* in our SOLAR SYSTEM. The planets orbit a central STAR we call the SUN.
Jupiter
Saturn
Mercury
Mars
Venus
Earth
Neptune
Uranus
Can you name the other planets?
Hit <RETURN> for answers
Rocky terrestrial planets of the inner solar system.
Gas & ice giant planets of the outer solar system.
Influenced by the gravity of Jupiter & Neptune, icy comets from the outer solar system likely delivered important ingredients for life to the young Earth environment (e.g. water and carbon compounds).
*The exact number depends on whether we call objects like Pluto “planets”.

9. Jupiter is the largest planet in our solar system.
Jupiter is a gaseous world without a solid surface.
Jupiter has twice the mass of all the other planets combined.
Jupiter is 10 times the diameter of Earth.
A thousand Earths would fit inside Jupiter.

10. Artist’s concept of 3 “extra-solar planets”
Artist rendering of Upsilon Andromeda
© 1999 Lynette Cook
Artist’s concept of 3 “extra-solar planets”
In the past decade, we have begun to detect the presence of Jupiter-sized worlds in orbit around other stars in our Milky Way galaxy.

11. The Goldilocks Effect Venus “Too Hot” Earth “Just Right!” Mars
“Too Cold”
Image composite of Venus, Earth, and Mars to scale in diameter.
Venus is shown in UV light
Mars image from Hubble Space Telescope
Composed by Dr. James Harold of the Space Science Institute:
Earth is in our solar system’s “habitable zone” where liquid water can exist on the surface.

12. A hundred Earths would fit across the diameter of the Sun.
Earth-sun distance
not to scale
A hundred Earths would fit across the diameter of the Sun.
A million Earths would fit inside the volume of the Sun.
Large, eruptive prominence in He II at 304Å, with an image of the Earth added for size comparison. This prominence from 24 July 1999 is particularly large and looping, extending over 35 Earths out from the Sun. Erupting prominences (when Earthward directed) can affect communications, navigation systems, even power grids, while also producing auroras visible in the night skies.
Source/Credits: Solar & Heliospheric Observatory (SOHO). SOHO is a project of international cooperation between ESA and NASA.

13. The Sun is the ONLY star in the SOLAR SYSTEM.
Earth is the ONLY planet in our solar system where we know for sure that life has evolved.

14. Our Place in the Galaxy
The Sun is the only star in the SOLAR SYSTEM, but it is one of over 100 billion stars in the GALAXY we call the Milky Way.
Our solar system is located about 2/3 of the way out from the galaxy’s center.
Astronomers think that most of the stars in the Milky Way galaxy could also have planets orbiting around them. These are called “extra-solar planets”.
Milky Way Bar
This artist's rendering shows a view of our own Milky Way Galaxy and its central bar as it might appear if viewed from above. An arrow indicates the location of our Sun. Astronomers have concluded for many years that our galaxy harbors a stellar bar, though its presence has been inferred indirectly. Our vantage point within the disk of the galaxy makes it difficult to accurately determine the size and shape of this bar and surrounding spiral arms.
New observations by the GLIMPSE legacy team with NASA's Spitzer Space Telescope indicate that the bar-shaped collection of old stars at the center of our galaxy may be longer, and at a different orientation, than previously believed. The newly-deduced size and angle of the bar are shown relative to our Sun's location. Our Milky Way galaxy may appear to be very different from an ordinary spiral galaxy.
Artist’s Concept of our Milky Way Galaxy

15. The term “Milky Way” is used in two ways.
For purposes of this presentation, we mean the whole galaxy.
1. “Milky Way” = our entire galaxy of 100 billion stars.* Our whole solar system orbits once around the galaxy’s center every 225 million years or so.
2. “Milky Way” = the band of light and dust that stretches across a dark night sky.* This is just a portion of one of the spiral arms that we can see from Earth.
* The image above is of another spiral galaxy that may be a lot like our own Milky Way. It would not be possible to make such an image of our own galaxy from within it. This galaxy is called NGC 4414.
* The image above is a long exposure photograph, showing much more contrast than we would see with our naked eye. To the eye, the “Milky Way” looks like a faint, whitish band with a few dark patches.

16. “What if we filled this whole room with crystals of salt?”
There’d be about a 100 billion crystals. That’s how many stars in the whole Milky Way galaxy!
“Milky Stars”
Mirrored Room:
part of the
Alien Earths
exhibit
What if we filled this whole room with crystals of salt?
D-12: Salt Room
“What if we filled this whole room with crystals of salt?”
That’s how many stars in the whole Milky Way galaxy! ~ 100 billion!

17. Assume the Sun is the size of a large grapefruit:
Q1. About how big would planet Earth be on this scale? [Show size with your hands or an object. <RETURN> for answer.]
A1: About the size of a pencil tip
Q2: On this scale, how far away would pencil-tip “Earth” be from the grapefruit “Sun”?
Of course, the Sun is really 10 billion times bigger than a grapefruit with a 14 cm diameter.
A2: About 15 meters (50 ft) away. Pluto would be about ½ mile away.
Q3: On this scale, how far away would the nearest star in the Milky Way galaxy be?
A3: About 5000 km (3000 miles).
The East-West distance across the US!

18. So in this scale model, the space between the Sun and the NEAREST STAR in the Milky Way galaxy is like having one grapefruit on the Golden Gate bridge in San Francisco, and another grapefruit on the Brooklyn Bridge in New York.
Images of spiral galaxies make it seem like stars are crammed closely together, but in reality there are vast distances between them.

19. So Many Stars, So Little Time
At the present time, our technologies enable us to search around the nearest stars in the Milky Way galaxy (the pink sphere) for extra-solar planets or signs of intelligent life.

20. We are searching in a tiny portion of the Milky Way galaxy, and yet our galaxy is only one of more than 100 billion galaxies in the Universe!
All but 4 specks in this “Hubble Deep Field” image are
entire galaxies, each of them with 100 billion stars.

21. A. Our Place in Space SUMMARY
Earth is one of 9 PLANETS that orbit a STAR we call the SUN [“3rd rock from the Sun”] The Sun is at the center of the SOLAR SYSTEM and is the ONLY star in the Solar System. Our SUN is one of over 100 billion STARS in the GALAXY we call the Milky Way We are detecting the presence of Jupiter-sized worlds in orbit around other stars in our Milky Way Galaxy. Our GALAXY is one of over 100 billion galaxies in the UNIVERSE!

22. “Earth’s Place in Space”
Test yourself on
“Earth’s Place in Space”
by taking a few minutes to play
TWO ASTRONOMY GAMES OR
Skip ahead to
PART B: Star & Planet Formation

23. [Field test version – May 2004]
Two Astronomy Games
"Small and LARGE"
"Near and Far"
Instructions for
“TWO ASTRONOMY GAMES”
[Field test version – May 2004]
Cherilynn Morrow, PhD
Thanks to:
Lise Roussin for reviewing the French translation
Preston Dyches for researching the distances between objects and Earth
Michael Zawaski and Preston Dyches for help with formatting the images
We are going to play two astronomy games, one that is called “Small and Large”, and another called “Near and Far”.
You can use these games with a large group, a few students or with just one other person.
Copyright Cherilynn Morrow
Two Astronomy Games Copyright Cherilynn Morrow – Used with permission

24. “Small and Large” “Near and Far” 1. 2. 3. 4. 5. 6. 7. 8. 9.
On a sheet of paper, make two columns like the ones below:
“Small and Large”
“Near and Far” 1. 2. 3. 4. 5. 6. 7. 8. 9.
Smallest
Closest
Please take out a sheet of paper. On the paper make two columns.
The title of the first column is “Small and Large” and the title of the second column is “Near and Far”.
In each column, write the numbers from “one” to “nine”.
Copyright Cherilynn Morrow
Largest
Farthest
Two Astronomy Games Copyright Cherilynn Morrow – Used with permission

25. SHOW THE IMAGES FOR THE GAME: “SMALL AND LARGE” [SLIDE # 4]
The next slide will show 9 images
Order the objects in these images from the smallest object (number 1) to largest object (number 9). Use the first column in the table you created.
Write the letter as well as the name of the object in the column. This way, you will have a list that you can consult later.
Are you ready?
Now let’s begin the first game – “Small and Large”. I am going to show you nine images. You must put them in order from smallest to largest
“Number one” corresponds to the image that contains the smallest image “Number nine” corresponds to the image that contains the largest image.
ARE YOU READY?
SHOW THE IMAGES FOR THE GAME: “SMALL AND LARGE” [SLIDE # 4]
Copyright Cherilynn Morrow
Two Astronomy Games Copyright Cherilynn Morrow – Used with permission

26. A. THE SUN B. EARTH C. SPACE SHUTTLE D. THE MOON E. THE SOLAR SYSTEM
F. BEARS
It would be best to write the letter as well as the name of the object in the column. This way, you will have a list that you can consult later.
Remember: “Number one” must be the smallest object in reality and “number nine”, the largest.
HINTS
Ask the students to respond before showing the solution. You can give one or more hints as needed. The letters below correspond to the letters representing the images.
A. The distance between the Sun and Earth is 400 times greater than the distance between the Moon and Earth.
C. The length of the Space Shuttle is 37 meters (121 feet).
G. The diameter of Mars is around half that of Earth.
H. The galaxy in this image cannot be our Milky Way because we are able to see the entire galaxy. It is not possible to travel outside of our galaxy to obtain an image like this one.
Copyright Cherilynn Morrow
G. MARS
H. A GALAXY
I. JUPITER
Press ENTER for a HINT
Mars has no oceans and the same
LAND area as Earth
Two Astronomy Games Copyright Cherilynn Morrow – Used with permission

27. The Solution "small and LARGE"
Ask students to respond before showing the solution.
SHOW THE SOLUTION [SLIDE # 6]
Copyright Cherilynn Morrow
Two Astronomy Games Copyright Cherilynn Morrow – Used with permission

28. SUMMARY NOTES and FREQUENTLY ASKED QUESTIONS
1F. BEARS
2C. SPACE SHUTTLE
3D. THE MOON
4G. MARS
5B. EARTH
6I. JUPITER
SUMMARY NOTES and FREQUENTLY ASKED QUESTIONS
Consider the diameter of Earth. You can compare it to the other objects in the pictures above. For example:
The diameter of the Moon is one-quarter that of Earth.
The diameter of Mars is half that of Earth.
The diameter of Jupiter (the largest planet in the solar system) is ten times that of Earth.
The Sun is the star at the center of our solar system. The diameter of the Sun is about one hundred times that of Earth.
Why do the Sun and the Moon appear to be the same size in the sky?
The diameter of the Sun is 400 times greater than the diameter of the Moon. But the Sun is 400 times farther from Earth.
What are the differences between a planet and a star?
- A star is much bigger and more massive.
- A star shines with its own light; a planet reflects the light from a star.
- Planets orbit around stars.
What is the difference between our solar system and a galaxy?
Our solar system has a star at its center called the Sun. There are nine planets that orbit around the Sun. The Sun is the only star in our solar system. On the other hand, there are more than a hundred billion suns (stars) in a galaxy like the one pictured.
Copyright Cherilynn Morrow
8E. THE SOLAR SYSTEM
9H. A GALAXY
7A. THE SUN
Two Astronomy Games Copyright Cherilynn Morrow – Used with permission

29. SHOW THE IMAGES FOR THE GAME: “NEAR AND FAR” [SLIDE # 8]
The next slide will show 9 images.
Order the objects in these images from the object that is nearest to the surface of Earth (number 1) to the object that is farthest from the surface of Earth (number 9). Use the second column in the table you created.
It would be best to write the letter as well as the name of the object in the column. This way, you will have a list that you can consult later.
Are you ready?
Now, the second game – “Near and Far”.
I am going to show you nine images. You must put the objects in these images in order from nearest to the surface of Earth (number 1) to farthest from the surface of Earth (number 9).
Use the second column. “Number one” corresponds to the object that is closest. “Number nine” corresponds to the object that is farthest.
ARE YOU READY?
SHOW THE IMAGES FOR THE GAME: “NEAR AND FAR” [SLIDE # 8]
Copyright Cherilynn Morrow
Two Astronomy Games Copyright Cherilynn Morrow – Used with permission

30. H. STARS OF THE BIG DIPPER I. SATURN
A. THE SUN
B. A GALAXY
C. AURORAS
Press ENTER for HINTS
If we see a whole spiral,
it can’t be our own galaxy.
Auroras occur in Earth’s
uppermost atmosphere
D. THE MOON
E. JET AIRPLANE
F. HUBBLE TELESCOPE
The Space Shuttle can visit
Hubble, but not the Moon
It would be best to write the letter as well as the name of the object in the column. This way, you will have a list that you can consult later.
Remember: “Number one” must be the object that is closest to the surface of Earth. “Number nine” must be the object that is farthest from the surface of Earth.
HINTS
Ask the students to respond before showing the solution. You can give one or more hints as needed. The letters below correspond to the letters representing the images.
A. The distance between the Sun and Earth is 400 times greater than the distance between the Moon and Earth.
B. This galaxy cannot be our galaxy (the Milky Way) because we are able to see the entire galaxy. It is not possible to travel outside of our galaxy to obtain an image like this one. If you can see the spiral structure of a galaxy, it is certain to be outside of our own galaxy.
C. Auroras are found in the highest regions of the atmosphere.
E. Usually, jet airplanes fly in the stratosphere, at more than 10 kilometers (6 miles) above the surface of Earth.
F. The Space Shuttle can visit the Hubble telescope to do maintenance or make repairs. The Space Shuttle cannot visit the Moon.
H. The stars of the constellations that we can see in the sky are located in our galaxy (the Milky Way).
I. Earth orbits the Sun at a distance of 1 AU (Astronomical Unit). Saturn orbits the Sun at a distance of 10 AU.
Copyright Cherilynn Morrow
G. AN EAGLE
H. STARS OF THE BIG DIPPER
I. SATURN
Stars we see are within
the Milky Way galaxy
Saturn is 10 times farther
from the Sun than Earth
Two Astronomy Games Copyright Cherilynn Morrow – Used with permission

31. The Solution “Near and Far”
Ask students to respond before showing them the solution.
SHOW THE SOLUTION: SLIDE # 10
Copyright Cherilynn Morrow
Two Astronomy Games Copyright Cherilynn Morrow – Used with permission

32. SUMMARY NOTES and FREQUENTLY ASKED QUESTIONS
G. AN EAGLE
E. JET AIRPLANE
C. AURORAS
D. THE MOON
A. THE SUN
F. HUBBLE TELESCOPE
SUMMARY NOTES and FREQUENTLY ASKED QUESTIONS
Why do the Sun and the Moon appear to be the same size in the sky?
The diameter of the Sun is 400 times greater than that of the Moon, but the Sun is 400 times farther from Earth than the Moon. That is why you can see a total eclipse of the Sun, during which the Moon blocks the light from the Sun.
How far from Earth’s surface are auroras?
Auroras are found from 95 to 190 kilometers (about miles) above the Earth’s surface.
How far from Earth’s surface is the Hubble telescope?
The Hubble telescope orbits around Earth at a distance of 600 kilometers (373 miles).
How far from Earth is the Moon?
The Moon is about 400,000 kilometers (250,000 miles) from Earth.
How far from Earth is the Sun?
The Sun is 1 Astronomical Unit = 150,000,000 kilometers (93 million miles) from Earth.
How far from Earth is Saturn?
From 9 AU to 11 AU. It depends on which side of the Sun that Saturn is on, relative to Earth.
How far is the Big Dipper from Earth?
That depends on the star. The brightest stars of this constellation are between 70 and 100 light-years from Earth. A light year is about 10 trillion kilometers (6 trillion miles). 10 trillion = 10,000,000,000,000
How far is the galaxy in the image from Earth?
This galaxy, NGC 4414, is 60 million light years from Earth.
Copyright Cherilynn Morrow
H. STARS OF THE BIG DIPPER
I. SATURN
B. A GALAXY
Two Astronomy Games Copyright Cherilynn Morrow – Used with permission

33. "Small and LARGE" "Near and Far"
These games are available on-line in multiple modalities:
As you see it here in PowerPoint
As a downloadable card game for the exhibit floor
As an on-line interactive
As a classroom activity
Go to
Click on “Traveling Exhibition” then “Education Program” then “Activities”
Ask students to respond before showing them the solution.
SHOW THE SOLUTION: SLIDE # 10
Copyright Cherilynn Morrow
Two Astronomy Games Copyright Cherilynn Morrow – Used with permission