This activity invites you to think about what you already know about stars before you watch the main lecture video for this lesson. We will be revisiting the life cycle of stars later in an activity called Star Comics.

Look at the Life of a Star Worksheet images of the different stages in the life of a star. Based on your knowledge and intuition, use the worksheet to arrange the images from the beginning to the end of the life of a star. You probably know more than you think you do. You have only 5 minutes so make your best guess (don’t worry; you’ll dig into how stars form in more detail soon). As you arrange the images, discuss with the people next to you the differences among them and what those differences might indicate about how old the star is.

In Unit 3 the Universe gets more complex and a whole lot brighter with the birth of stars. The earliest stars in our Universe began forming about 100 million years after the Big Bang. But that’s not the only new complexity in this unit. When stars die, or run out of fuel, they scatter the Universe with new chemical elements. Those elements add a new level of complexity that is very important for the creation of planets, life, and us!

The Big History narrative crosses thresholds of increasing complexity, and the two thresholds in this unit add a lot of new complexity to the Universe. You’ll learn about the birth of the first stars and how these stars give us new chemical elements necessary for life. You’ll also meet a “guest star” and examine how ancient historical texts can provide modern astronomers with insights about the Universe.

Preview

As a reminder, open and skim the transcript, and read the questions before you watch the video.

Key Ideas – Factual

Think about the following questions as you watch this video:

1. What is a supernova?
2. How do ancient historical texts, such as The Book of the Later Han, help scientists today understand astronomical phenomena like supernovae?
3. How did modern astronomers confirm that the “guest star” recorded by Chinese astronomers was in fact a supernova?
4. What is interdisciplinarity (interdisciplinary thinking) and why is it important in the Big History course?
5. What are the two thresholds for this unit?
6. How do stars “light up”?
7. How do dying stars create the building blocks for life?

Thinking Conceptually

1. This video shows an example of how historical information can change the way we understand events today. Can you think of any historical events that have shaped your own life?
2. What are some other examples of discoveries that use interdisciplinary thinking?

Understanding vocabulary is integral to you being able to access course content, and it helps reading comprehension, too. This word wall activity should help you begin to learn some of the key vocabulary from Unit 3.

In this activity, you’ll work with your class to create a word wall using the Unit 3 vocabulary.

Your teacher will assign a vocab card to each of you. Once you get yours, take a few minutes to look it up in the Unit 3 Vocab Guide and then examine the unit itself (click around and quickly skim the content) to see where in the unit your word might be most applicable. Then, add as many synonyms to your card for your word as possible. Be careful if you decide to use the “related words” section from the vocab guide—it doesn’t distinguish between synonyms and antonyms. Your teacher will give you a limited amount of time to write synonyms. Then, the people with the most correct synonyms at the end of that time will put their words on the word wall first.

Your teacher may add some fun twists to this assignment, so be sure to listen closely for directions!

Historical events rarely have a single cause. Some causes happen right before the event; some long before; others, a really long time before. Some play a central role; some merely contribute to the event; others trigger the event. Some causes are essential while others are less important. And, the importance of causes may change depending on the questions you ask about that event. Understanding cause and effect helps historians analyze change over time.

It also helps us establish connections between events over time, which gives us the opportunity to connect historical events to our own lives. In this causation practice progression activity, you’ll identify the causes and triggering event that led to the birth of the Universe’s first stars. This will help you understand how stars form and will also establish patterns of thinking you will use later in the course.

Scale
Using causation as an analytical tool for studying history helps us add dimension to one of the core pillars of BHP—scale. Causation is another way of examining historical events from different perspectives, and the scale or periodization at which we examine those events informs how we analyze them.

In this activity, you’ll learn about the process of star formation and its triggering event. You’ll use this knowledge to create a visual causal map on your desk about the formation of stars.

1. Think about and discuss with your class the triggering event that led to Alphonse’s demise in the Alphonse the Camel story that you read in the first causation activity in the course. (Remember, a triggering event is the most immediate or recent cause of an event.)
2. Now, watch How Were Stars Formed? and think about the causes of star formation while you watch the video.
3. Take the Causes Cards and divide them into long term, intermediate term, and short term. Place the cards on the relevant sections of the Causation Tool. Then, put the event in the middle of the tool, and label the triggering event with a star (*).
   After you’ve discussed the placement of the cards with your class, you’ll create a map that shows the causes of star formation. This is called a causal map. These maps help you visualize connections between causes and events by showing how different events are linked together. Unlike a timeline, a causal map might take the form of a web or cycle rather than a straight line. Usually, things that lead up to an event don’t happen one after the other (linearly), like dominoes falling. Often it takes a bunch of things happening, some of them at the same time, to lead to the event.
4. Arrange the Causes Cards into a causal map that shows connections. If you want, you can tape the Causes Cards to the back of the Causation Tool, drawing arrows in between the causes leading to star formation. Make sure that your triggering event is closest to the event (in this case, star formation).

The expansion of the Universe enabled atoms and energy to spread out. This created small pockets of activity across an otherwise empty space. In these little areas, gravity pulled together atoms, and then more and more atoms, until the first stars came to life. Stars attracted other stars to form galaxies. Galaxies attracted other galaxies to form clusters, and then clusters came together to form superclusters.

Everything around us is made up of atoms. To understand how atoms are formed, we have to understand how stars die. To understand how stars die, we have to understand how they are formed. This video explains how stars formed out of the increasingly cold and empty early Universe.

Preview

In the moments after the Big Bang, the Universe immediately started expanding, cooling off as it did. This allowed some of the energy to convert into matter. This then allowed atoms such as hydrogen, helium, and a few others to form and float. Over time, these atoms were drawn together by gravity and started heating up as they did so. The denser these pockets of atoms got, the more atoms were drawn together. Finally, enough atoms were drawn together and the heat became intense enough that a star was born! This process happened all over the Universe. Stars too were drawn together by gravity, forming galaxies. Galaxies were drawn together to form clusters. Finally, clusters were drawn together to form superclusters.

Key Ideas

Think about these questions as you watch the video:

1. What Goldilocks Conditions were necessary for the formation of stars?
2. How does gravity work?
3. What conditions trigger the process of star formation?
4. Why do stars get together as galaxies? Why do galaxies get together as clusters, and so on?

Thinking Conceptually

Do you think the process of new stars forming continues today? Is our star one of the first stars formed or did it form later?

You will need a copy of your Thresholds Graphic from Lesson 2.0, Narrative and Thresholds – the Big Bang. If you skipped that activity, you can use the Threshold Graphic included in the PDF for this activity.

The eight thresholds of increasing complexity are fundamental to the Big History Project, and they help us remember the modern, scientific origin story that is Big History. By continuing to revisit the thresholds, and by coming up with your own version of the Big History story, you’ll be better able to connect and remember what you are learning in this course.

Reading, writing, causation
Building on the image analysis skills that you practiced in the last Narrative and Thresholds activity, in Lesson 2.0, you will use the BHP Thresholds Graphic to reflect upon what you learned and how it connects to the next threshold. As part of this activity, you’ll take a few minutes to write the Big History story in your own words. All of the thresholds dance around the idea of causation. Goldilocks Conditions are certainly contributing factors—or maybe even triggering events!

Take out your BHP Thresholds Graphic. Look at the image for Threshold 2: Stars Light Up. Try to guess what this threshold is about and how it relates to the prior threshold. Next, watch the video, Threshold 2: The Stars Light Up.

Once you’ve watched the video, create a hashtag or two that you think best describe this threshold, add them to the graphic, and then be prepared to share your ideas with the class.

Next, take out a piece of paper, and in just a few minutes, do the best job you can writing a brief Big History narrative. Remember that one of the things we are doing here is trying to remember the big BHP story, and the big turning points in that story, so that as we learn more in a unit, we have a framework for remembering the story. This is meant to be fun and informal, so do your best and make sure you include the thresholds. This will help you see how the thresholds are all connected to one another. It’s OK if some of this is guessing and predicting. You’ll have opportunities to revise this brief narrative later on in the course.

The expansion of the Universe enabled atoms and energy to spread out. This created small pockets of activity across an otherwise empty space. In these little areas, gravity pulled together atoms, and then more and more atoms, until the first stars came to life. Stars attracted other stars to form galaxies. Galaxies attracted other galaxies to form clusters, and then clusters came together to form super clusters, which introduced new structural complexity into our Universe.

This short video about Threshold 2: The Stars Light Up, quickly introduces the threshold. This sets the stage for learning more about star formation and provides the relevant background knowledge for you to understand Threshold 3: New Chemical Elements.

Preview

After the Big Bang, the Universe was small and incredibly hot, but that state didn’t last. The Universe began to grow, and as it grew, atoms had more room to move around without crashing into each other. Things cooled off. Let’s look at how stars formed in this cold, dark period after the Big Bang.

Key Ideas – Factual

Think about these questions as you watch the video:

1. What was the Universe like before the first stars formed? How long was it after the Big Bang before stars started to form?
2. Why do atoms packed together tightly heat up?
3. How long do stars continue releasing energy into space?

Thinking Conceptually

How does this threshold connect to what you learned about the Big Bang (Threshold 1)?

Cecilia Payne-Gaposchkin wrote a dissertation that challenged our understanding of stars. Before her discoveries, scientists believed that stars contained the same chemical elements as Earth. Cecilia proved that they were misinterpreting the spectra, or bands of light, from distant stars. Yet, her male colleagues doubted her evidence. This doubt pressured Cecilia to include a line of uncertainty in her dissertation. Nonetheless, within five years, her thesis was confirmed—by the same colleagues who had doubted her along the way!

In this unit, you are learning about the birth and death of stars. Though these processes have been going on for billions of years, our understanding of what makes up a star is actually quite recent. This biography of Cecilia Payne-Gaposchkin illustrates the revolutionary impacts of new ideas. As a graduate student, Cecilia challenged established science and revolutionized a discipline, despite her own doubts and those of her peers and mentors. Her discovery helped push our collective learning forward in the twentieth century as humanity peered ever closer at the stars.

Read 1: Observe

As you read this graphic biography for the first time, review the Read 1: Observe section of your Three Close Reads for Graphic Bios Tool. Be sure to record one question in the thought bubble on the top-right. You don’t need to write anything else down. However, if you’d like to record your observations, feel free to do so on scrap paper.

Read 2: Understand

On the tool, summarize the main idea of the comic and provide two pieces of evidence that helped you understand the creator’s main idea. You can do this only in writing or you can get creative with some art. Some of the evidence you find may come in the form of text (words). But other evidence will come in the form of art (images). You should read the text looking for unfamiliar vocabulary words, the main idea, and key supporting details. You should also spend some time looking at the images and the way in which the page is designed. By the end of the second close read, you should be able to answer the following questions:

1. What does the graphic biography tell you about Cecilia’s early life?
2. Why did Cecilia decide to become an astronomer? What obstacles did she face?
3. What was Cecilia’s greatest discovery? Who doubted her claims?
4. How does the page's design, text, and illustrations contribute to your understanding of Cecilia’s story?

Read 3: Connect

In this read, you should use the graphic biography as evidence to support, extend, or challenge claims made in this unit of the course. On the bottom of the tool, record what you learned about this person’s life and how it relates to what you’re learning.

1. How does Cecilia’s story add to what you’ve learned about collective learning so far in this course?

To Be Continued…

On the second page of the tool, your teacher might ask you to extend the graphic biography to a second page. This is where you can draw and write what you think might come next. Here, you can become a co-creator of this graphic biography!

Before stars, the Universe was cold and dark. With gravity pulling at areas where there were just a few more atoms, clouds of atoms soon formed. These clouds got denser and denser until finally, the temperature got really, really hot—over 10 million degrees. At this point, atoms started fusing together and bam! A star is born.

Clip 12:05 – 16:47. This clip from the H2 program Big History explains the formation of stars. It is a short clip that provides a highly visual explanation, reinforcing the explanation from David Christian in the earlier video.

Preview

The Universe was initially too hot for even atoms to form. Yet after about 380,000 years, things cooled down enough for atoms to form. Drawn together by gravity, these atoms gather in dense clouds into stars.

Key Ideas

Think about these questions as you watch the video:

1. What draws atoms of hydrogen and helium together into clouds?
2. What happens as these clouds get larger?
3. What was different about the Universe once stars arrived?

In this activity, you’ll search for and read news articles that reveal unexpected connections between today’s world and the time when the first stars lit up to understand how things we learn today may support, extend, or challenge what we already know about this second threshold of increasing complexity. Exploring how our knowledge of the birth of stars continues to develop today will help you connect more with the theories related to Threshold 2: Stars Light Up and will help you understand how those theories have changed over time.

Reading, claim testing
As part of this activity, you’ll be reading news articles online. These will vary in difficulty and style, so, where possible, use the skills you’ve learned as part of the Three Close Reads process to help you better understand these texts. When searching for information online, you’ll also use claim testers to evaluate credibility of the sources you encounter.

The second major threshold of increasing complexity in this course is the birth of the first stars. Until stars lit up, the Universe was relatively cold and dark and had very little visible structure. The intense heat and pressure and the energy generated by stars would eventually enable still more complexity, such as planets and even life. This threshold is crossed over and over again, as new stars form continually in places in the Universe called nebulae. These different stars are born, live, and die over millions and billions of years. Stars of different sizes, or masses, have different life cycles. Scientists, and all of us, continue to learn more about star formation and the colorful lives of stars.

You can join in this process of discovery by searching for news stories about the stars. Use some of the suggested websites below or find ones on your own that highlight new information that you think contributes to a discussion of stars today. As you look for new information related to stars, don’t forget to think about the credibility of the authors and of the websites you are using to determine whether or not you can trust the claims being made.

Keep these questions in mind to determine an article’s credibility:

• What person or group is behind the website where you found the article?
• Why are they sharing this information?
• What authority do the website and author have on the topic?

In thinking about these questions, you may need to do additional research to find out more about the source, which might involve opening a new tab and searching for information about a publication, group, or author. This search can help you determine why an article was written in the first place, who its intended audience is, and relevant background information on the author or website.

Answering the questions the questions above will help you decide if an author or website is credible. The next step is to examine perspective in the article. To do this, ask yourself:

• How does the author’s perspective impact their argument?

Perspective—the specific viewpoint of the author—can influence the way they tell a story or draw conclusions. Because we all have unique experiences and opinions, our perspectives nearly always play a role in the way we give and receive information. However, it’s important to examine authorial perspective in an article to see if the claims being made are being backed up with supporting statements (hello, claim testing!). Are statements supported by evidence? Does the author address counterarguments? Answering these questions will help you determine if the author’s perspective is making an argument unfair or one-sided.

Take out the This Threshold Today: Stars Light Up worksheet and record your sources and some of the details about what you discover in your search. Here are some websites you might find helpful (but feel free to use others):

• Live Science: The Most Interesting Articles, Mysteries & Discoveries
• ZME Science: Not Exactly Rocket Science
• Space.com: NASA, Space Exploration and Astronomy News
• Smithsonian Magazine: History, Travel, Arts, Science, People, Places
• Science News Magazine

Each unit of the Big History course is guided by a driving question. You’re learning a ton of stuff in this and every other unit, and it can be hard to keep track of what’s most important. It would be pretty easy to become obsessed with a detail that, although interesting and a great way to impress people at a party is relatively unimportant. This activity will help you stay focused! You’ll think about the unit’s driving question, and then you’ll respond to it in writing. By journaling these questions and responses, you’ll see how much you’ve learned as you move through each section of the course.

Think about this question: How can looking at the same information from different perspectives pave the way for progress?

Use the DQ Notebook – Unit 3 Worksheet to respond to this question as best as you can. Be prepared to talk about these ideas with your class.

The main lecture for this lesson explained in detail the life of a star. Now it’s time for you to document the process in your own words by creating a comic strip. This activity will help you to formalize your understanding of the life of stars and make it easier for you to remember the stages in the future.

Create a comic strip that explains the process of a star forming. Your comic strip needs to be at least five panels, but you may make it longer if you want. Use the template provided here or another one your teacher has approved for your comic strip. For each panel, draw (or trace) a picture and include text that explains what’s going on. Remember to come up with your own explanations—no copying and pasting. Don’t obsess about being exact. Instead, highlight the different attributes and characteristics of each star stage in a way that explains the differences to readers. Get the facts right and have fun!