Finding Life Beyond Earth

Expand/Collapse Finding Life Beyond Earth


Powerful telescopes and unmanned space missions have revealed a wide range of dynamic environments—atmospheres thick with organic molecules, active volcanoes, and vast saltwater oceans. This ongoing revolution is forcing scientists to expand their ideas about what kinds of worlds could support life. In NOVA's Finding Life Beyond Earth, top astrobiologists explain how these places are changing how we think about the potential for life in our solar system.

The resources below explore questions at the heart of the search for extraterrestrial life, such as "What is life?" and "Where do we find habitable conditions?" in order to encourage a better understanding of the existence of life in our solar system.

For additional classroom resources, download the activity collection of seven hands-on activities that explore questions at the heart of the search for extraterrestrial life. You can also download the solar system poster to use as a visual aid in your classroom.

  • How the Inner Solar System Formed

    In this video segment adapted from NOVA, learn how our solar system formed from a cloud of gas and dust more than 4.5 billion years ago. Watch video that features real satellite imagery as well as simulations to illustrate how small bodies in the early solar system collided with each other to form larger objects and early planets (protoplanets). See how computer simulations have shown that over tens of millions of years, collisions between hundreds of protoplanets formed the rocky inner planets we see today.

    Grades: 6-12
  • Life's Basic Ingredients

    This video excerpt from NOVA explains what astrobiologists consider to be the three basic ingredients of life—water, organic compounds, and energy. Although Earth has water and energy, scientists are trying to learn how organic molecules got to our planet. Some believe that comets could help us understand how the final ingredients necessary for life arrived on Earth. In activity two from the Education Collection that accompanies this video, students observe a number of objects, make a list of life’s characteristics, and develop a working definition of being alive.

    Grades: 6-12
  • Comets Bombard the Early Earth

    In this video segment adapted from NOVA, learn how key ingredients for life may have been delivered throughout the solar system by comets and asteroids billions of years ago. Watch video that features real satellite imagery as well as simulations to explore a dynamic model of solar system evolution. Learn how the gravitational interactions of Jupiter and Saturn could have destabilized the early solar system, leading to a 100-million-year period, known as the Late Heavy Bombardment, in which comets and asteroids were scattered throughout the solar system and collided with other objects (including the early Earth). Impact craters visible on moons and planets may be evidence of this period.

    Grades: 6-12
  • Life's Extreme Environments

    In this video excerpt from NOVA, meet organisms that thrive in a wide variety of harsh conditions, such as dry deserts, toxin-laden lakes, dark caves, and acidic rivers. These microbes—dubbed extremophiles—show life’s adaptiveness and are broadening scientist’s understanding of the diverse environmental conditions life can withstand. Since similar conditions have been detected or inferred on other planets or moons, microbes might live there as well. In activity four from the Education Collection that accompanies this video, students match a microbe to an extreme environment in which it could live using cards that show extremophiles and some of Earth’s extreme environments.

    Grades: 6-12
  • Microbial Life in Antarctica

    In this video excerpt from NOVA, visit one of the most extreme deserts on Earth—the dry valleys of the Antarctic—that resembles the surface of Mars. Watch as scientists drill into the Mars-like soil and ice, where they discover microorganisms in a film of liquid water at the point where the dirt meets the ice. In activity four from the Education Collection that accompanies this video, students match a microbe to an extreme environment in which it could live using cards that show extremophiles and some of Earth’s extreme environments.

    Grades: 6-12
  • Thriving on the Arctic Seafloor

    In this video excerpt from NOVA, follow biologist Tim Shank as he explores the deep Arctic Ocean, which may be similar to the ocean on one of Jupiter's moons called Europa. Robots sent to the ocean floor discover a hostile environment that is home to new forms of life that use sulfur, hydrogen, and methane as chemical sources of energy. In activity four from the Education Collection that accompanies this video, students match a microbe to an extreme environment in which it could live using cards that show extremophiles and some of Earth’s extreme environments.

    Grades: 6-12
  • Life on Enceladus?

    This video segment adapted from NOVA follows NASA’s Cassini mission to Saturn and the surprising discoveries it has made about Enceladus, one of Saturn’s 62 moons. Carolyn Porco, leader of the Cassini mission’s science imaging team, describes some of the features Cassini observed on this icy moon, including a series of large cracks named “tiger stripes,” through which jets of frozen vapor shoot upward into space. Porco describes the process that explains why liquid water can exist under the surface of Enceladus despite its extreme distance from the Sun. She also explains why she believes this frozen moon may be the best candidate to harbor life beyond Earth. The video features real satellite imagery as well as simulations.

    Grades: 6-12
  • Life on Europa?

    In this video excerpt from NOVA, learn about Jupiter’s moon Europa. Images reveal a surface covered with jagged areas of ice that appear to have melted, broken apart, and frozen back together. The pattern is similar to the one made by sea ice on Earth. Readings of Europa’s magnetic field indicate that an electric current is flowing inside, consistent with an ocean of salty, liquid water beneath the icy surface that could be 60 miles deep. In activity six from the Education Collection that accompanies this video, students examine 12 cards that describe the habitability of the planets and six moons. Based on their assessment, students identify the top candidates for life in the solar system.

    Grades: 6-12
  • Life on Mars?

    In this video excerpt from NOVA, learn about the discovery of water ice on Mars. Satellites analyzing radar waves bouncing back from Mars's polar caps reveal that if it all melted, there is enough water ice to cover the entire planet in an ocean more than 80 feet deep. However, just like a piece of dry ice on Earth goes directly from solid ice to vapor without forming a liquid, water ice on Mars behaves the same way because the pressure is so low. In activity six from the Education Collection that accompanies this video, students identify the top candidates for life in the solar system.

    Grades: 6-12
  • Life on Titan?

    In this video excerpt from NOVA, learn about Titan, the largest moon of Saturn. Through radar imaging, scientists discover that Titan’s surface is covered with hundreds of lakes filled with liquid methane and ethane, making it the only world other than Earth that has a liquid on its surface. In activity six from the Education Collection that accompanies this video, students examine 12 cards that describe the habitability of the planets and six moons. Based on their assessment, students identify the top candidates for life in the solar system.

    Grades: 6-12
  • Life Beyond the Solar System

    In this video excerpt from NOVA, learn how the Hubble Space Telescope is being used to find dense disks of dust and gas particles forming around new stars like our Sun. These gas and dust particles may one day collide and clump together to form new planets and moons in a process similar to how the planets in our solar system could have formed. In activity seven from the Education Collection that accompanies this video, students observe four demonstrations of different techniques used in the search for life.

    Grades: 6-12
  • Planet-Hunting

    In this video segment adapted from NOVA, learn about the hunt for Earthlike planets outside our solar system that may harbor life. Astronomer Geoff Marcy explains the challenges of finding infinitesimally small planets orbiting huge, very bright stars. By monitoring the light from distant stars, sensitive instruments can detect the very slight dimming that occurs when objects, such as orbiting planets, pass in front of them. The video also introduces us to NASA’s Kepler space telescope, launched in 2009 to discover Earth-sized planets and determine how many of the billions of stars in our galaxy have such planets. The video features real satellite imagery as well as simulations.

    Grades: 6-12
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  • Where to Look for Life

    Students examine 12 cards that describe the planets and six moons in terms of their temperature and atmosphere and the availability of water, energy, and nutrients. Based on their assessment of the habitability, students identify the top candidates for life in the solar system.

    Grades: 1-6
  • Grades: 1-6

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