Tell students that Activity 1 (Constructing an Argument) of the lesson Is There Live in Space? introduces the structure of the scientific argumentation they will be asked to do in the rest of the lesson. Tell students that Activity 1 will give them practice with analyzing a data set and making a good scientific argument from the evidence. Encourage students to review the questions and example best answers provided in Activity 1 before starting on the current activity.

1. Activate students' prior knowledge about our solar system.

Tell students that Earth is the only planet in our solar system known to have life. Ask:

• What factors do you think are necessary for life to exist on a planet? (Some commonly known factors for life include liquid water, an atmosphere, and having energy sources. Some students may say that oxygen is necessary. If this happens, you can point out that there are some organisms on Earth that do not require oxygen.)

Tell students that scientists are looking for planets and moons that might have characteristics necessary for supporting life. Explain that scientists have already found thousands of planets outside our solar system. Let students know that they will be learning how scientists search for planets and how they determine whether the planets they find have the potential to support life.

2. Discuss the role of uncertainty in the scientific process.

Introduce students to the concept of uncertainty in the scientific process. Explain that science is a process of learning how the world works and that scientists do not know the “right” answers when they start to investigate a question. Tell students that they can see examples of scientists' uncertainty in determining whether or not the data collected from telescopes show the presence of planets.

Show the Kepler Planet Candidates graph from the NASA Exoplanet Archive. Tell students that the red dots indicate potential planets the Kepler telescope has detected and the blue dots indicate the planets the Kepler telescope detected and have been confirmed by other means. Ask:

• Why do you think there are more red dots than blue dots (more potential planets than confirmed planets)? (The telescope may detect planets that are not there. The technology may not be good enough to tell the difference between a planet and some other phenomenon.)
• Why do scientists need to independently confirm the presence of planets? (Scientists need to check the accuracy of the telescope's predictions of a planet. If the telescope shows a planet and the scientists confirm that it is a planet, then the scientists can spend more time trying to learn about the planet.)

Let students know that they will be asked questions about the certainty of their predictions and that they should think about what scientific and model-based data are available as they assess their certainty with their answers. Encourage students to discuss the scientific evidence with each other to better assess their level of certainty with their predictions.

3. Have students launch the interactive The Vastness of Space.

Provide students with the link to the interactive The Vastness of Space. Divide students into groups of two or three, with two being the ideal grouping to allow students to share computer workstations. Tell students they will be working through a series of pages of data with questions related to the data. Ask students to work through the activity in their groups, discussing and responding to questions as they go.

NOTE: You can access the Answer Key for students' questions—and save students' data for online grading—through a free registration on the High-Adventure Science portal page.

Tell students this is Activity 2 in the Is There Life in Space? lesson. 

4. Discuss the issues.

After students have completed the activity, bring the groups back together and lead them in a discussion focusing on these questions:

• How do scientists detect planets? (Scientists use light from stars to detect planets.)
• Why do scientists have to use stars to find planets? (Planets don't give off their own light so they are difficult to see in the darkness of space. Stars are bright, so they are easier to see.)
• How do scientists use light from stars to find planets? (Scientists can use light from stars in two ways: [1] they can look at the movement of the light towards and away from Earth to find a wobble in the star's orbit, and [2] they can look for dimming of the light from the star.)
• What factors are necessary for life to exist on a planet? (Scientists think that liquid water is necessary for life. Living things also need a source of energy and a place to exist [rocky body, such as a planet, moon, or asteroid].)

1. Activate students' prior knowledge about Newton's Third Law of Motion.

Tell students that for every action, there is an equal and opposite reaction. Ask:

• Imagine you have a dog on a leash. When the dog pulls on the leash, what do you feel? (When the dog pulls on the leash, you feel a pull towards the dog.)
• What does the dog feel? (The dog feels an equal force pulling it back towards you. The force is equal to and opposite of the force that you feel in the leash.)

Explain to students that scientists use this concept to find planets orbiting around stars. Tell students that the gravitational pull of planets can move their stars as they orbit. 

2. Discuss the role of uncertainty in the scientific process.

Introduce students to the concept of uncertainty in the scientific process. Explain that science is a process of learning how the world works and that scientists do not know the “right” answers when they start to investigate a question. Tell students that they can see examples of scientists' uncertainty in determining whether or not the data collected from telescopes show the presence of planets.

Show the Kepler Planet Candidates graph from the NASA Exoplanet Archive. Tell students that the red dots indicate potential planets the Kepler telescope has detected and the blue dots indicate the planets the Kepler telescope detected and have been confirmed by other means. Ask:

• Why do you think there are more red dots than blue dots (more potential planets than confirmed planets)? (The telescope may detect planets that are not there. The technology may not be good enough to tell the difference between a planet and some other phenomenon.)
• Why do scientists need to independently confirm the presence of planets? (Scientists need to check the accuracy of the telescope's predictions of a planet. If the telescope shows a planet and the scientists confirm that it is a planet, then the scientists can spend more time trying to learn about the planet.)

Let students know that they will be asked questions about the certainty of their predictions and that they should think about what scientific and model-based data are available as they assess their certainty with their answers. Encourage students to discuss the scientific evidence with each other to better assess their level of certainty with their predictions.

3. Introduce and discuss the use of computational models. Explain the concept of computational models, and give students an example of a computational model that they may have seen, such as forecasting the weather. Project the NOAA Weather Forecast Model, which provides a good example of a computational model. Tell students that scientists use planetary models to predict the motion and apparent brightness of stars if planets are present and to predict the habitability of planets. Explain that there are many different types of models and that they will be using simple models of planetary motion in this activity.

4. Have students launch the Moving Stars and Their Planets interactive.

Provide students with the link to the Moving Stars and Their Planets interactive. Divide students into groups of two or three, with two being the ideal grouping to allow students to share computer workstations. Tell students they will be working through a series of pages of data with questions related to the data. Ask students to work through the activity in their groups, discussing and responding to questions as they go.

NOTE: You can access the Answer Key for students' questions—and save students' data for online grading—through a free registration on the High-Adventure Science portal page.

Tell students this is Activity 3 in the Is There Life in Space? lesson.

5. Discuss the issues.

After students have completed the activity, bring the groups back together and lead them in a discussion focusing on these questions:

• What is the Doppler effect? (The Doppler effect is the apparent change in wavelength as an object moves. As the object moves closer, the wavelength decreases, and as the object moves away, the wavelength increases.)

• How do scientists use the Doppler effect to find planets around a star? (Planets pull on their stars as they orbit, thus moving the star. If the star is in the same plane as the observer, the observer can see that the light coming from the star appears to become redder as the star moves away and bluer as the star moves closer. The changing wavelengths indicate that the star is moving. If this movement is regular, it is likely that a planet is causing the star to move.)

1. Engage students in a discussion about eclipses.

Explain to students that in a solar eclipse, the Moon moves directly between the Earth and Sun. Tell them that an eclipse may be total, in which the Moon appears to block the entirety of the Sun, or partial, in which the Moon blocks only a part of the Sun. Ask:

• What happens to the Sun's brightness, as seen from Earth, during a solar eclipse? (When the Moon moves between the Sun and Earth, the Sun appears to dim.) 
• Which type of eclipse causes more dimming effect, as seen from Earth: a partial eclipse or a total eclipse? (A total eclipse will cause more dimming because the entire face of the star is blocked. During a partial eclipse, there is less dimming because the Moon does not completely obscure the Sun.)

Tell students that scientists use planetary eclipses to find planets around stars. As the planets move around their stars, they can block some of the light from that star, just as our Moon can block light coming from our Sun during a solar eclipse.

2. Discuss the role of uncertainty in the scientific process.

Introduce students to the concept of uncertainty in the scientific process. Explain that science is a process of learning how the world works and that scientists do not know the “right” answers when they start to investigate a question. Tell students that they can see examples of scientists' uncertainty in determining whether or not the data collected from telescopes show the presence of planets.

Show the Kepler Planet Candidates graph from the NASA Exoplanet Archive. Tell students that the red dots indicate potential planets the Kepler telescope has detected and the blue dots indicate the planets the Kepler telescope detected and have been confirmed by other means. Ask:

• Why do you think there are more red dots than blue dots (more potential planets than confirmed planets)? (The telescope may detect planets that are not there. The technology may not be good enough to tell the difference between a planet and some other phenomenon.)
• Why do scientists need to independently confirm the presence of planets? (Scientists need to check the accuracy of the telescope's predictions of a planet. If the telescope shows a planet and the scientists confirm that it is a planet, then the scientists can spend more time trying to learn about the planet.)

Let students know that they will be asked questions about the certainty of their predictions and that they should think about what scientific and model-based data are available as they assess their certainty with their answers. Encourage students to discuss the scientific evidence with each other to better assess their level of certainty with their predictions.

3. Introduce and discuss the use of computational models. 

Explain the concept of computational models, and give students an example of a computational model that they may have seen, such as forecasting the weather. Project the NOAA Weather Forecast Model, which provides a good example of a computational model. Tell students that scientists use planetary models to predict the motion and apparent brightness of stars if planets are present and to predict the habitability of planets. Explain that there are many different types of models and that they will be using simple models of planetary motion in this activity.

4. Have students launch the Hunting for Planets interactive.

Provide students with the link to the Hunting for Planets interactive. Divide students into groups of two or three, with two being the ideal grouping to allow students to share computer work stations. Tell students they will be working through a series of pages of data with questions related to the data. Ask students to work through the activity in their groups, discussing and responding to questions as they go.

NOTE: You can access the Answer Key for students' questions—and save students' data for online grading—through a free registration on the High-Adventure Science portal page.

Tell students this is Activity 4 in the Is There Life in Space? lesson.

5. Discuss the issues.

After students have completed the activity,  bring the groups back together and lead a discussion focusing on these questions:

• How does a planet's size affect its ability to be discovered via the transit method? (The transit method relies on detecting dimming of a star as planets orbit. If the planet is very large, it can block more of the light coming from the star. A high level of dimming is easier to detect than a smaller level of dimming. Therefore, larger planets are more likely to be detected than smaller planets.)
• How does the angle of orbit affect a planet's ability to be detected? (A planet needs to orbit in the same plane as the scientists' telescopes to be able to be detected reliably. This is particularly important when using the transit method. If the telescope is even slightly out of the orbital plane, the dimming will not be detected. The wobble (radial velocity) method is more robust, since that depends on detecting motion (wavelength shift) of the star, not the brightness of the star.)
• How does telescope “noise” affect planet hunting? (Scientists are more likely to discover larger, heavier planets than smaller, lighter ones because of the effect of telescope noise. The signals from smaller, less massive planets are smaller than the signals from larger, more massive planets. The smaller signals can get lost in the data “noise,” making it difficult to determine whether a planet is present.)

1. Engage students in a discussion about conditions that are necessary for life.

Introduce the idea that there is a variety of living things on Earth that live in a wide variety of environments—from organisms that live in hot springs to organisms that live in the Antarctic ice. Ask:

• What conditions are necessary for life to exist on a planet? (Scientists think that liquid water is necessary for life. They also think that a habitable planet should have an atmosphere.) 
• Do you think that a planet should be exactly like Earth to be able to support life? (Student answers will vary. Students should recognize that there is a wide variety of conditions on Earth that have life, so there could be planets that are very different from Earth that still have some habitable regions. Humans would not survive at the bottom of the ocean, but there are many organisms that thrive there. Some organisms use sulfur compounds for respiration, instead of oxygen; humans would die without oxygen.) 

Tell students that scientists look for certain characteristics of planets to assess their potential habitability.

2. Discuss the role of uncertainty in the scientific process.

Introduce students to the concept of uncertainty in the scientific process. Explain that science is a process of learning how the world works and that scientists do not know the “right” answers when they start to investigate a question. Tell students that they can see examples of scientists' uncertainty in determining whether or not the data collected from telescopes show the presence of planets.

Show the Kepler Planet Candidates graph from the NASA Exoplanet Archive. Tell students that the red dots indicate potential planets the Kepler telescope has detected and the blue dots indicate the planets the Kepler telescope detected and have been confirmed by other means. Ask:

• Why do you think there are more red dots than blue dots (more potential planets than confirmed planets)? (The telescope may detect planets that are not there. The technology may not be good enough to tell the difference between a planet and some other phenomenon.)
• Why do scientists need to independently confirm the presence of planets? (Scientists need to check the accuracy of the telescope's predictions of a planet. If the telescope shows a planet and the scientists confirm that it is a planet, then the scientists can spend more time trying to learn about the planet.)

Let students know that they will be asked questions about the certainty of their predictions and that they should think about what scientific and model-based data are available as they assess their certainty with their answers. Encourage students to discuss the scientific evidence with each other to better assess their level of certainty with their predictions.

3. Introduce and discuss the use of computational models. 

Explain the concept of computational models, and give students an example of a computational model that they may have seen, such as forecasting the weather. Project the NOAA Weather Forecast Model, which provides a good example of a computational model. Tell students that scientists use planetary models to predict the motion and apparent brightness of stars if planets are present and to predict the habitability of planets. Explain that there are many different types of models and that they will be using simple models of planetary motion in this activity.

4. Have students launch the Habitable Conditions interactive.

Provide students with the link to the Habitable Conditions interactive. Divide students into groups of two or three, with two being the ideal grouping to allow students to share computer workstations. Tell students they will be working through a series of pages of data with questions related to the data. Ask students to work through the activity in their groups, discussing and responding to questions as they go. 

NOTE: You can access the Answer Key for students' questions—and save students' data for online grading—through a free registration on the High-Adventure Science portal page.

Tell students this is Activity 5 in the Is There Life in Space? lesson. 

5. Discuss the issues.

After students have completed the activity, bring the groups back together and lead a discussion focusing on the following questions:

• Why does the habitable zone change around different star types? (The habitable zone, roughly defined as the area where liquid water can exist on a planet's surface, is different around different star types because different stars have different temperatures. Around a cool star, the habitable zone will be closer to the star. Around a hot star, the habitable zone will be farther from the star.)
• Show the model on page 4 of the activity.

According to this model, what characteristics make a planet suitable for life? (A planet should be rocky, orbit entirely in the liquid water zone, and orbit a M, K, G, or F class star.)

• Do you think that a planet needs to orbit completely within the zone of liquid water possibility to be able to have life? (Student answers will vary. Students should note that the zone of liquid water possibility means that water can be liquid on the planet's surface. There can still be liquid water below the surface that could support living things. In this case, with liquid water under the surface, life could exist on a planet that orbits in-and-out of the zone of liquid water possibility.)

1. Activate students' prior knowledge about atmospheres.

Tell students that Earth's atmosphere is a mixture of gases, 78% nitrogen, 21% oxygen, and 1% all other gases, including carbon dioxide, water vapor, argon, etc. Ask: 

• What gases do you think are necessary for life? (Students may state that oxygen is necessary for life, but there are many forms of life on Earth that do not need oxygen.)
• How do you think scientists determine if a planet has an atmosphere and what gases are in its atmosphere? (Students may state that scientists have to send probes to the planets to sample their atmospheres. Tell students that most planets are too far away to send probes to get information directly.)

Let students know that scientists use light from planets' stars to analyze the atmospheres of the planets.

2. Discuss the role of uncertainty in the scientific process.

Introduce students to the concept of uncertainty in the scientific process. Explain that science is a process of learning how the world works and that scientists do not know the “right” answers when they start to investigate a question. Tell students that they can see examples of scientists' uncertainty in determining whether or not the data collected from telescopes show the presence of planets.

Show the Kepler Planet Candidates graph from the NASA Exoplanet Archive. Tell students that the red dots indicate potential planets the Kepler telescope has detected and the blue dots indicate the planets the Kepler telescope detected and have been confirmed by other means. Ask:

• Why do you think there are more red dots than blue dots (more potential planets than confirmed planets)? (The telescope may detect planets that are not there. The technology may not be good enough to tell the difference between a planet and some other phenomenon.)
• Why do scientists need to independently confirm the presence of planets? (Scientists need to check the accuracy of the telescope's predictions of a planet. If the telescope shows a planet and the scientists confirm that it is a planet, then the scientists can spend more time trying to learn about the planet.)

Let students know that they will be asked questions about the certainty of their predictions and that they should think about what scientific and model-based data are available as they assess their certainty with their answers. Encourage students to discuss the scientific evidence with each other to better assess their level of certainty with their predictions.

3. Introduce and discuss the use of computational models. 

Explain the concept of computational models, and give students an example of a computational model that they may have seen, such as forecasting the weather. Project the NOAA Weather Forecast Model, which provides a good example of a computational model. Tell students that scientists use planetary models to predict the motion and apparent brightness of stars if planets are present and to predict the habitability of planets. Explain that there are many different types of models and that they will be using simple models of planetary motion in this activity.

4. Have students launch the Looking for Signs of Life interactive.

Provide students with the link to the Looking for Signs of Life interactive. Divide students into groups of two or three, with two being the ideal grouping to allow students to share computer workstations. Tell students they will be working through a series of pages of data with questions related to the data. Ask students to work through the activity in their groups, discussing and responding to questions as they go.

NOTE: You can access the Answer Key for students' questions—and save students' data for online grading—through a free registration on the High-Adventure Science portal page.

Tell students this is Activity 6 in the Is There Life in Space? lesson.

5. Discuss the issues.

After students have completed the activity, bring the groups back together and lead a discussion focusing on the following questions:

• How can scientists tell what elements are in a mixture of gases? (Scientists use spectroscopy to detect which elements are in a mixture of gases. Each element absorbs light in a unique pattern. By analyzing the light going into the atmosphere and the light coming out of the atmosphere, scientists can determine what elements are in the atmosphere.
• How can scientists use planetary spectra to search for life on other planets? (Scientists can analyze the composition of the planet's atmosphere. If the planet has gases that are conducive to life or indicate that life may be present, they can then investigate further for life.)