Are we alone? Is there intelligence elsewhere in the universe? It sounds like a simple question, and for most people there's an obvious answer: Of course we aren’t! After all, the universe is so big. In addition to the staggering numbers of galaxies composed of billions of stars, the history of science has shown that every time we think we are special in some way, we turn out to be wrong. The sun does not revolve around the Earth, the sun is not the only star, we are not the center of our galaxy, and our galaxy is not the center of the universe. There may even be multiple universes. Like so many important questions for which there are little data but different ways to examine the question, finding an answer can get complicated very quickly.
What would a planet need to have to support life? Why is liquid water the key to supporting life in our universe? How can we find planets with liquid water? Can we possibly communicate with extraterrestrial life? These are some of the questions that are important to think about. Radio astronomy could allow us to tune into the correct radio frequency – the one that other intelligent life might utilize. New data suggests there are more habitable zones out there than we'd previously thought. But how can we find them? Research continues, built on the work and vision of many who believe simple extraterrestrial life in our solar system and beyond will be found in the not-too-distant future.
A cursory glance at history shows that, even when people are routinely suffering due to societal upheaval, some fraction of any civilized nation's resources have gone to seeking new things, or creating new things. Along with the intrigue and excitement searching for alien life involves, the costs and benefits of programs designed to search for and communicate with extraterrestrial life must also be considered. Is reaching out into the infinite of space worth it?
In this lesson, students will watch and discuss ideas from the Are We Alone? episode. They will discuss specific points and ideas from the video (see discussion questions) with each other, in collaborative groups, and as a whole class.
After engaging in conversation about the discussion questions, students will form collaborative groups to focus on one of the following five topics based on the Are We Alone? episode:
- Search for Extraterrestrial Intelligence – SETI
- Keeping the Faith
- Water, Water, Everywhere?
- Detecting Life on Other Planets
- The Costs and Benefits of Finding Extraterrestrial Life
Students will obtain and evaluate information from the Are We Alone? episode and other PBS Learning Media resources to clarify and further investigate the topic they choose. They will then communicate this information to their peers in a way they choose, selecting one or two clips from the resources to support and clarify their information.
Organized and deliberate classroom discussions can help students practice the skills of the Scientific and Engineering Practice obtaining, evaluating, and communicating information from the Next Generation Science Standards (NGSS). Engagement in these practices follows what scientists and engineers do as they go about their work. It is language intensive and requires students to participate in classroom science dialogue.
4-5 class periods
Obtain, evaluate, and communicate information about various aspects of investigating the existence of extraterrestrial life.
Introduce the episode “Are We Alone?” to students, explaining that they will be using the information from this video to focus on an aspect of the search for intelligent life that interests them.
Use the following discussion questions to stimulate conversation both before and after viewing. Consider pairing or grouping students together to discuss and answer specific questions, then ask students to present their views, opinions, and gathered facts to their class. You may want to give the discussion questions to the students during viewing.
Before viewing, for the entire class:
- Ask students, “Do you believe there is extraterrestrial life? Why or why not?
- Throughout the video, students will see that the use of technology has allowed us to reach into other worlds in various ways throughout history. Before showing this episode, challenge students to reflect upon and record the ways technology has enhanced our understanding of other places and worlds that may be able to support life. How has that technology changed over time? Several scientists from centuries ago and the late 20th century are discussed in the episode, along with the technology used and the discoveries made or ideas generated. Students should discuss these scientists/ideas/discoveries and how they enabled others who came after to discover new technologies and ideas allowing further studies of extraterrestrial life.
Click to watch:
After viewing, in small collaborative groups:
- Hawking says answering the question, “are we alone?”, is one of humanity’s most important challenges. Why is this question considered to be so important? Do you agree that this is an important question? (Answers will vary.)
- What makes life possible? (A source of energy from an object like our star, the sun is the initial primary resource.)
- What is the Milky Way composed of? (Billions and billions of stars, planets, gas, interstellar dust.)
- Galileo discovered that stars formed the bulk of the Milky Way. How was Galileo’s way of studying the world different from what other scientists were doing? (Galileo experimented, used scientific tools, gathered data. He used technology developed for sea navigation and used it to study the stars…which showed him the Milky Way was composed of billions and billions of stars (approx. 300 billion).
- What would an alien life form need to exist? (A planet to live on – one that has water.)
- In 1584 the philosopher Giordano Bruno engaged in the practices of science by asking questions, constructing explanations based on evidence and communicating information. What information did he communicate that cost him his life? In today’s world, how likely is this to happen? Why or why not? (He stated that stars could be surrounded by planets which could support ‘alien’ life; for this he was burned at the stake.)
- Why can’t we clearly see a planet orbiting a distant star when it passes in front of it? (It is lost in the glare of its star.)
- How did scientists figure out a way to detect these planets orbiting other stars? (A planet orbiting a star will fractionally reduce the amount of starlight reaching observers on Earth. Computers, telescopes and other sensitive equipment can confirm the existence of another planet going around another star.)
- Why is working out how much light is blocked by a passing planet in front of a star so important? (It can tell the size of a planet and the possibility of whether that planet could support life; could intelligent life be found there? If we can determine planet size, we would then know where to look in our galaxy…or beyond. With over 300 billion stars, you have to know where to look!)
- What is the purpose of the NASA Kepler Mission? (To hunt for solar systems using a telescope out in space in order to find Earth-size, rocky planets in or near the ‘habitable zone’. The Kepler Mission measures the tiny, telltale dip in the brightness of a star that can be produced by a transiting planet. What has it found? More and more planets that could support life – over 4000!)
- What makes a planet suitable for life? (WATER, the essential liquid. It is abundant and made up of two of the most common elements, Hydrogen and Oxygen. It is liquid over a wide range of temperatures and can react with other molecules easily.)
- What is critical about a rocky planet’s distance from its star? (The distance determines whether liquid water can be found which would possibly support life.)
- What is the Goldilock’s Zone? (The location, neither too close to the sun nor too far away, where water could exist to support life.)
- How does Jupiter’s moon Europa show us that other sources of heat besides a star could still support life? (Europa’s distance from the sun causes the water on its surface to be frozen solid. Europa’s elliptical orbit changes its distance around Jupiter as it orbits so Jupiter’s gravitational pull is different at different times – this stretching and squishing on Europa squishes the inside of Europa, causing heat which then causes its ice to melt. So, there is another way to heat a planet that would make it habitable for life by melting water…)
- How do we know other life forms may be trying to communicate with us? (We listen to the combined sound of the universe with radio telescopes; there is a lot of noise however!)
- How can we hear what another life form may be communicating with us? (Use one band of frequency with very few vibrations! Within this band is a unique frequency that could be used for long distance communication - the hydrogen line frequency. With hydrogen being the most common element in the universe, the possibility is intriguing that other intelligent life forms would know about and also know how to use it to communicate. However, all the other ‘white noise’ must first be suppressed.)
- What is SETI and what does it do? (Search for Extraterrestrial Intelligence - It has been scanning the galaxy for over 30 years, but has found no proof that alien life exists; it is privately funded and not a tax payer supported program.)
- What does the flame that annihilated the lone, single ball signify? (Anything can happen in nature! Human life is fragile. Advanced alien life occurs so rarely and briefly that we are unlikely to make contact.)
After engaging in conversation about the discussion questions, students should form collaborative groups to focus on one of the following five topics based on the "Are We Alone?" episode. You can assign students to groups or show the students the list of 5 to allow them to pick the one they would be most interested in. Set the parameters for t heir work (time allowed, homework expectations (if any), what the end product is that you expect and what the criteria are for their end product, etc.) Allow them access to the Resources listed above in order to choose at least one clip and/or selection from an essay that supports their information. If students use outside resources found on the Internet, make sure they are aware of the protocols for referencing their work and how to avoid plagiarism.
1. Search for Extraterrestrial Intelligence (SETI): What are the SETI scientists looking for and why? Discuss what you think is scientific and unscientific about the SETI project, using evidence from the videos to explain your answer. There are hundreds of billions of stars in the universe, and possibly hundreds of billions of planets (remember that our Sun has at least 8 planets!). What do you think the chances are of other forms of life being out there — unlikely, likely or probable? What do scientists and mathematicians think?
a. Genius "Are We Alone?" video clip — Who’s Calling?
b. Genius "Are We Alone?" video clip — How Many Stars? (click to watch)
c. NOVA clip — Search for Extraterrestrial Intelligence: Are We Alone? (click to watch)
2. Keeping the Faith: If intelligent life is found elsewhere, it would raise interesting theological questions. How would the discovery of extraterrestrial life affect religious thought on humanity's place in the universe? Read some of the short essays here, in NOVA's Life's Little Essential: Liquid Water.
3. Water, Water, Everywhere? What is the argument in favor of the idea that liquid water is essential to life? Have other substances been proposed? Why do planetary scientists search for evidence of liquid water on other planets? Planetary scientists are quick to stress that it's not just water that's indispensable for life, but liquid water.
a. Genius "Are We Alone?" video clip — Water, Water, Everywhere? (click to watch)
b. NOVA's Life's Little Essential: Liquid Water essay.
4. Detecting Life on Other Planets:
a. Genius "Are We Alone?" video clip — Other Ways to Heat a Planet? (click to watch)
b. NOVA interactive — Detecting Life Beyond Earth
c. NOVA video — Life on Europa?
5. The Costs and Benefits of Finding Extraterrestrial Life: Analyze the costs and benefits of pursuing the existence of life elsewhere – how would it benefit us? Drawing from the "Are We Alone?" episode, identify the costs involved with specific projects (such as the Kepler Mission), technology (radio telescopes for example) and/or equipment (to support any project discussed or shown in the video) that are or would be part of the search of extraterrestrial life. Compare and analyze these relative costs to the benefits they might provide to society. What impact, if any, would the cost of pursuing intelligent life elsewhere in our universe have on serious societal concerns here on Earth, including environmental issues? Be careful in your research – some major programs such as SETI are not funded via tax dollars but with private funding. Do you believe the pursuit of the existence of life elsewhere should continue?
Determine how students will share their information from their small group with others. If all groups have a digital product consider having them save them on an online storage site (such as Google Docs) or a safe school site so all students can go in and view each of the group products, either at home or in class. Finally, consider convening a science conference to have students share with each other what they saw, what they think of the information presented, and whether or not they agree with particular viewpoints presented. The use of a guide or graphic organizer for each project presented will help students focus on the main points offered and gather their own thoughts for sharing (and grading) later.