In this activity, you’re faced with a challenge that forces you to consider what you would do and where you would go if you had to flee the surface of the Earth. This challenge will help you apply the scientific knowledge and methods that you’ll learn about in this lesson and the next, and it will also push you to work like scientists. You’ll create hypotheses based on the challenge, and then modify and support your hypotheses throughout the next two lessons as you learn more.

Imagine Earth is facing a mass extinction event. This extinction event is going to make the surface of the Earth uninhabitable, but you are being given an opportunity to flee to an uninhabited place beneath the Earth’s surface, the Moon, or another planet in the Universe in the next 365 days. In groups, you are going to try to answer this question, and as you learn more in the next two lessons, your group is going to revise and clarify your answer to this question to make sure that your plan is supported by as much science as possible.

Your teacher will divide you into groups. Be sure your group has a copy of the Fleeing the Surface of the Earth (Part 1) Worksheet. Your group should take about 10 minutes to come up with a hypothesis about where you’ll go, why you would go there, when you would go, and how you would get there. You must also come up with some ideas about how you would ensure your survival once you’ve arrived at your new home. Be as scientific as you can, but you can also get creative with some of your answers. Be prepared to share where you group decided to go and why.

The Solar System is one star, many planets, a lot more asteroids, and even more icy comet-like objects. It formed from a collapsing cloud, which flattened into a disk, which is why the Solar System is flat. We see the same thing happening out in the galaxy, too. We are only one of possibly billions of solar systems in the Universe. 

This video reinforces what you already know about the formation of the Solar System, and goes on to explain more. In addition to covering how human understanding of the Solar System has developed over time, there is an in-depth explanation of the details behind what happened when our Solar System formed. The deeper understanding of accretion will help you understand what’s currently happening in our Solar System, as well as why it is what it is today. 

Preview

In this episode of Crash Course Astronomy, Phil Plait looks at the history of our cosmic backyard, also known as our Solar System. He explains how we went from a giant ball of gas to the system of planets and other celestial objects that exist today. 

Key Ideas – Factual

Think about the following questions as you watch the video:

1. What kind of model did Copernicus propose for the Universe? One that changed people’s views on Ptolemy’s idea of a geocentric Universe?
2. Why does Phil Plait assert that you can’t define a planet?
3. What facts or trends does Plait claim are giving us hints about how the Solar System was formed?
4. What is angular momentum and how does it work?
5. What are planetesimals and how are they formed?
6. Why did some material form planets and other material did not?

Thinking Conceptually

How does thinking about the formation of the Solar System help you understand what’s happening in the Universe today? Why might it be important to understand what’s happening in the Universe today? 

After initial calculations by Percival Lowell and William Pickering led to speculation about a ninth planet, amateur astronomer Clyde Tombaugh finally discovered Pluto in 1930. Over time, additional bodies of similar size and composition were discovered until it was determined that Pluto was not unique. In 2006, the International Astronomical Union reclassified Pluto as a dwarf planet. 

This article will give you a deeper look at a larger body traveling across our Solar System: the dwarf planet Pluto. Pluto has long fascinated us, but more important, this article provides critical background into the process of observation in astronomy and highlights changes in prevailing wisdom. 

Skimming for Gist

Pluto was first discovered in 1930 and was designated as a ninth planet in our Solar System. Over time, astronomers discovered other, similar icy rocks out beyond Uranus, and ultimately they determined that rather than a unique object in the Solar System, Pluto was one of many. This collection of bodies was renamed the Kuiper belt and Pluto was reclassified as a dwarf planet, along with Ceres and Eris. 

Understanding Content

By the end of the second close read, you should be able to answer the following questions:

1. Why did Percival Lowell and William Pickering believe there was a ninth planet?
2. Who finally discovered Pluto?
3. When were the moons of Pluto discovered?
4. Does Pluto have other moons?
5. What is the Kuiper belt?
6. Why was Pluto reclassified as a dwarf planet? 

Thinking Conceptually

In the past, the work of identifying new bodies in space was very, very tedious. What are some of the ways today’s technology might make this easier? 

The purpose of this activity is to revisit scale, one of the core themes of Big History, by looking more closely at our Solar System and trying to build a scale model of it outside. You will have to use mathematical calculations to understand the methodology that scientists use in trying to understand and model scale.  

It’s surprisingly hard to build a scale model of the Solar System where the same scale is used to portray not only the physical sizes of the Sun and planets, but also the distances between them. The pictures you see of the Solar System are actually not accurate, so you’re going to make your own scale model to get a better sense of how big our Solar System really is. People build two kinds of models—scale models and nonscale models. For example, model cars are often to scale, but relief globes are not. If relief globes were built to scale, the mountains wouldn’t be as high as they are depicted on the globes. You actually wouldn’t feel the mountains at all, because the Earth is so big compared to the size of the mountains.

In scale models, all linear sizes and distances are reduced or enlarged by the same factor so that they are in proportion to the original. For example, in a 1:20 scale model car, the length, width, and height of the car are all one twentieth of the corresponding dimensions of the real car.

Working alone or in groups, you are going to be responsible for calculating the sizes of the planets and the distances between them, using the Scale Model of the Solar System Worksheet. Once everyone has calculated the appropriate distances, the class will figure out how to construct the model outside.

Once the worksheets are complete, make a sign for each planet showing the name of the planet in large letters (big enough to be visible from other distant planets), as well as the size of the planet drawn to scale (some planets may be just a dot). This will give you an idea of just how large the distances are between planets compared to the size of the planets. 

In this video, a group of people built a scale model of the Solar System. Not only did they space the planets appropriately, they also had correct proportions so that we could really see how big the Sun and each of the planets are as part of the scale. Pictures can’t capture the Solar System to scale, because to fit on a piece of paper, the planets would be too small to see. 

In this video, which you’ll probably remember from Unit 1, you’ll see how some filmmakers made a scale model of the Solar System outside, pretty much like what you did in the last activity. You’ve already grappled with the idea of scale in relation to our Solar System, and this will deepen your understanding and give you an idea of how other people construct scale models.

Preview

On a dry lake bed in Nevada, a couple of filmmakers and their friends built a scale model of the Solar System complete with planetary orbits. This is a great illustration of how Earth fits into the Universe. 

Key Ideas – Factual

Think about the following questions as you watch the video:

1. Why aren’t pictures of the Solar System to scale?
2. How much space do you need to build a scale model of the Solar System if the Earth is only the size of a marble?
3. What planet orbits at the edge of the Solar System?
4. How do you know that they’ve made their model correctly, with the right proportions?

Thinking Conceptually

After watching this video, do you think the model that you created as a class in the last activity is still a good model? Was anything missing from the model? Did you get it wrong or was it correct, even though it didn’t look like the one in the video?

Comets consist of three key parts: the core, the gassy coma, and the tail. As they move through the Solar System, they teach us about solar radiation and the solar winds, but they also pose potential risk to the Earth itself. 

This article provides a brief history and overview of comets that will help you understand their significance, and the potential danger they represent. 

Skimming for Gist

Famously called “dirty snowballs,” comets were once thought to be portents of doom. A mixture of water and rock that can date back billions of years, these travelers across the Solar System have a lot to teach us. 

Understanding Content

By the end of the second close read, you should be able to answer the following questions:

1. Prior to the sixteenth century, what did people think comets where? 
2. What are the three components of a comet? 
3. Why did Fred Whipple call comets “dirty snowballs”? 
4. What creates a comet’s tail? 
5. What are some reasons scientists are interested in comets? 

Thinking Conceptually

How do comets differ in importance from other bodies you might find in our Solar System?

Have on hand your completed Fleeing the Surface of the Earth (Part 1) Worksheets.

In this activity, you’re asked to revisit the challenge that was presented at the beginning of this lesson. Now that you’ve gained some more concrete understanding about the solar system and its scale, you will use that information to make more informed decisions about where you would go when fleeing the surface of the Earth. Your group can change its original hypotheses—doing so doesn’t mean you were wrong when you started, just that you know more now. Changing your mind based on things you’ve learned models what scientists often do as they investigate possible answers to their questions. In addition, doing this should help you gauge whether or not you understood and were able to apply what you learned in this lesson. 

You need to finalize your plans about where you will go, how far away it is from the surface of the Earth, how long it would take you to get there, and what you would use to get there. If you chose a location in outer space, you must use your scientific knowledge about the scale of the Solar System and your ability to calculate distances when talking about how far away your chosen location is.

In figuring out distance, you will be asked to complete some mathematical calculations about how long it would take get where you’re going. You should complete this calculation by using the distance of the location and speed of the vehicle you will use get there. So, for example, if you were going to go to a planet 100,000,000 miles away, traveling in a plane that goes 100 miles per hour, it would take you 100,000 hours, or over 11 years to get there.

Remember the original challenge:  

Imagine Earth is facing a mass extinction event. This extinction event is going to make the surface of the Earth uninhabitable, but you are being given an opportunity to flee to an uninhabited place beneath the Earth’s surface, the Moon, or another planet in the Universe in the next 365 days. In groups, you are going to try to answer this question, and as you learn more in the next two lessons, your group is going to revise and clarify your answer to this question to make sure that your plan is supported by as much science as possible

Get into your groups and be sure you have both your completed Fleeing the Surface of the Earth (Part 1) Worksheet as well as the blank Fleeing the Surface of the Earth (Part 2) Worksheet. Provide the following information on the new worksheet, along with a rationale for why you kept or changed your original destination.

• Distance to that destination
• Method of transportation
• Length of time to travel to destination
• Why you decided on that as your final destination

You may need to do some research online to gather information and make decisions about where you are going and how you are getting there.

Be prepared to share your answers with the class. Also, in the next lesson, you’re going to revisit this challenge to provide more details about your plans based on what you now know and what you are going to learn.