Exoplanets: Planets Beyond the Milky Way

For generations, people have wondered if there is life on other planets, and for just as long, scientists have explored this possibility. In part, our curiosity is fueled by a rich imaginative narrative tradition, from Alien to the X-Files and everything in between (a short list of the “in between” would include: E.T., 2001: A Space Odyssey, Men in Black, Avatar, WALL-E, War of the Worlds, Thor, Superman, and Star Trek). What would other beings be like? What would it be like to meet them? Our interest is also piqued by the possibility of finding another planet on which we could live. Are there any Earth-like planets?

Time and again we are reminded of the interconnectedness of life. It is easy to see how this is so for life on Earth; however, have you ever thought about how you are connected to outer space? Watch the video, We are All Connected. It features quotes from astronomer Carl Sagan, physicist Richard Feynman, astrophysicist Neil deGrasse Tyson, and Bill “the Science Guy” Nye. Summarize the video: what is its overarching message? Watch a second time, and record one statement that stands out for you and your response to it. What statements stood out for classmates and why? The scientists featured in the video are (or were) leaders in their fields. Responses to their comments may inspire interesting discussions.

For many years we knew of only nine planets. (But then Pluto was demoted to a dwarf planet so now we know of eight planets.) Now, new technology allows scientists to explore planets beyond the Milky Way. These extrasolar planets, or exoplanets, are planets outside our solar system. As of November 30, 2011, 704 exoplanets have been identified. How are exoplanets identified from so far away? How will scientists know which are most likely to be Earth-like? This week scientists outlined a new classification system for deciding which exoplanets might support life, and therefore deserve further exploration.

This week, you will turn your attention to the solar system and explore exoplanets. First, you will visit the Kepler Mission to join the search for habitable planets. You will also travel with PlanetQuest to learn more about how our thoughts about space have evolved, and to try your hand at designing a planet.

The Search for Habitable Planets

Named after Johannes Kepler, the 17th century mathematician and astronomer who identified the laws of planetary motion, NASA’s Kepler telescope debuted in 2009. Select a video and watch its lift-off from Cape Canaveral. Begin your introduction to the Kepler mission by watching the video overview. As you watch, use these questions to monitor your understanding:
• What is Kepler’s mission?
• How long will Kepler scan its piece of the galaxy?

• How is Kepler’s mission unique?
• What is the golden zone and why is it important to finding Earth-like planets?
• How does Kepler differ from other telescopes?
Read more about the what, when, why, and how of Kepler’s mission.

Kepler finds planets by monitoring light input. Changes in the light projected from a star may be caused by something passing in front of it. If the changes follow a pattern, it indicates that a planet is orbiting the star; each time the planet passes, it temporarily blocks the light. To see this process, view an animation of how Kepler discovers planets. Scroll your mouse over the Kepler telescope first, then move counter-clockwise over each term.

Try your hand at being a Kepler scientist. Observe a transit, identify the star’s type, mass, radius, and temperature. Record transits. Calculate the habitable zone position, surface temperature, and radius to receive your star’s summary. Finally, visit your star. Compare your star with classmates. How are they different? Why are they (not) habitable.

Read last week’s article published in Time magazine on the new system for assessing life on other planets. On what two questions are exoplanet researchers focused? What is measured in the ESI? Why are these important on Earth-like planets? Why do researchers believe it is important to consider Earth-like and not Earth-like? What does the PHI measure and what are the implications of this on our search for life on other planets?

Return to NASA’s Kepler site and consider the chart of Kepler’s discoveries. Select three exoplanets to evaluate. How are they like or not like Earth? Explain why human life could (or could not) exist on each.

Bringing the Exploration to You

Fly over to NASA’s Jet Propulsion Laboratory’s PlanetQuest and take a trip on the historic timeline. The timeline, which begins automatically, traces milestones in space exploration. Which milestones are particularly interesting to you? Which seem especially significant? Note the exoplanet counter in the upper right corner. As you explore, keep an eye on the counter. When is the first exoplanet discovered? When is there an explosion in exoplanet discoveries? What technologies, methods, or theories contribute to this?

Visit PlanetQuests multimedia menu. Here you will find an assortment of videos and interactive options. Simply click on one to launch it. You learned earlier that Kepler uses the transit method to detect exoplanets. What other methods are used? Find out; click on the video Four Ways to Find a Planet. Summarize the methods that you understand best. Create a drawing that visualizes each. Write a list of questions for those that perplex you. Share your questions with peers. Can any classmates shed light on those methods? Can you answer any peers’ questions?

If you have not already, watch PlanetQuest: the Movie to hear from planet hunter, Geoff Marcy. What questions do you have for Marcy? Marcy says the key is to find planets that are rocky. Think back to the two ways of assessing planets. What type of planet is Marcy interested in finding? Marcy refers to the NASA projects that will identify terrestrial planets. Learn more about these missions by watching the Overview video. How will each mission add to our understanding of exoplanets?

Finally, try your hand at creating a planet with NASA’s Extreme Planet Makeover. Check out the presets in the bottom right corner. Note the measurements for Earth, Mars, and Gilese 581. Visit the Planet Gallery in the upper right corner and explore planets in our galaxy and beyond. Which are most like Earth? Select two to analyze: why is it not habitable? What measurements would have to change and how to make it more habitable? Before you leave, design your planet. Explain which measurements make your planet habitable (or not). You may download a picture of your planet using the camera icon in the bottom left. Share and compare your planet with classmates’.

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Newspaper Activities

Read the news in The Sacramento Bee for news related to space explorations. Record your questions. Create a class map of questions. Cluster those that are related. In teams, research a cluster of questions. Share your findings with your class.