The Traveling Exhibit

TheTraveling Exhibit Alien Earths Science Background Part A: INTRO & Our Place in Space prepared by Dr. Cherilynn Morrow for the Space Science Institute Boulder, CO

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

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.

Welcome to theExhibit Alien Earths • 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 The science background is organized by EXHIBIT AREA:

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

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

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 2000 Cherilynn Morrow – Used with permission artscienceducation@yahoo.com

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”.

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.

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.

The Goldilocks Effect Venus “Too Hot” Earth “Just Right!” Mars “Too Cold” Earth is in our solar system’s “habitable zone” where liquid water can exist on the surface.

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.

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.

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”. Artist’s Concept of our Milky Way Galaxy

The term “Milky Way” is used in two ways. For purposes of this presentation, we mean the whole galaxy. 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. 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. * 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.

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

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 • Of course, the Sun is really 10 billion times bigger than a grapefruit with a 14 cm diameter. • Q2: On this scale, how far away would pencil-tip “Earth” be from the grapefruit “Sun”? • 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!

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.

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.

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.

A. Our Place in Space 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 WayWe 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! SUMMARY

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

Game # 1: "Small and LARGE" • 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? Two Astronomy Games Copyright 2004 Cherilynn Morrow – Used with permission artscienceducation@yahoo.com

A. THE SUN B. EARTH C. SPACE SHUTTLE D. THE MOON E. THE SOLAR SYSTEM F. BEARS 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 2004 Cherilynn Morrow – Used with permission artscienceducation@yahoo.com

1F. BEARS 2C. SPACE SHUTTLE 3D. THE MOON 4G. MARS 5B. EARTH 6I. JUPITER 8E. THE SOLAR SYSTEM 9H. A GALAXY 7A. THE SUN Two Astronomy Games Copyright 2004 Cherilynn Morrow – Used with permission artscienceducation@yahoo.com

Game # 2: "Near and Far" • 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? Two Astronomy Games Copyright 2004 Cherilynn Morrow – Used with permission artscienceducation@yahoo.com

B. A GALAXY A. THE SUN 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 G. AN EAGLE I. SATURN H. STARS OF THE BIG DIPPER Stars we see are within the Milky Way galaxy Saturn is 10 times farther from the Sun than Earth Two Astronomy Games Copyright 2004 Cherilynn Morrow – Used with permission artscienceducation@yahoo.com

G. AN EAGLE C. AURORAS E. JET AIRPLANE D. THE MOON A. THE SUN F. HUBBLE TELESCOPE H. STARS OF THE BIG DIPPER I. SATURN B. A GALAXY Two Astronomy Games Copyright 2004 Cherilynn Morrow – Used with permission artscienceducation@yahoo.com

"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 www.alienearths.org. • Click on “Traveling Exhibition” then “Education Program” then “Activities” Two Astronomy Games Copyright 2004 Cherilynn Morrow – Used with permission artscienceducation@yahoo.com

The Traveling Exhibit