Big Idea 2.1

Introductory: A younger learner (K-5), or a learner new to the subject matter.

Quick Facts

How can life exist on Earth?

  • Educator Background

    Earth is the only place in the universe that we know of where life exists. Life exists on Earth because of many important factors: we have the perfect-sized star to live next to, we are the perfect distance from the Sun , it's not too hot or too cold, and we have liquid water. It is no surprise we call the place where Earth is located the "Goldilocks Zone" or the "Habitable Zone." Earth also has an atmosphere and a magnetosphere, which form protective layers around Earth.

  • Learning Constraints

    At this level students know that plants need sunlight and water to grow (2-LS2-1) and begin to learn about the energy flow from the Sun to plants, and then to other organisms in the ecosystem (K-LS1-1)(5-LS1-1). Students at this level are also familiar with the planets in the solar system and that most places are far too cold or too hot to live! As they progress, students will also be able to articulate which objects in the solar system have atmospheres and magnetospheres, and which do not. For example, students know that they can't breathe on the Moon or Mars.

  • Connect to Heliophysics

    Connect to the Sun by emphasizing the uniqueness of Earth's position in the solar system, within the Goldilocks Zone. Not only are we unique in our solar system, but unique in the universe. NASA looks for evidence of life on planets around other stars, and so far, we have not found another planet like Earth. Both Venus and Mars are in the Goldilocks Zone, but Mars doesn't have a very robust atmosphere and it is too cold for most organisms. Venus has a toxic atmosphere and has extremely hot temperatures. The Earth is very, very special.

  • Extend Exploration

    Extend student exploration by investigating extremophiles on Earth that can live in extreme environments. For example, bacteria that can survive in boiling acid. Scientists think that if life exists elsewhere in the universe, it may be an extremophile. But even the most extreme organisms on Earth rely on water to live, even if it is a very small amount. So scientists look for the existence of water on other planets, with the hope that someday we will discover some sort of life there.

  • Differentiate for Beginner Learners

    Support younger students by emphasizing the need for both sunlight and water for plants to grow.

  • Differentiate for More Advanced Learners

    Challenge students at the next level by exploring the flow of solar energy into plants, which are then consumed in other parts of the ecosystem.

Featured Introductory Resources

Explore this guiding question with these featured resources.

An animated image of Eyes on Exoplanets interface showing stars of the Milky Way.

Interactive NASA Data

Eyes on Exoplanets

A poster with several animations

Video + Poster

Searching for Other Planets Like Ours

Several people demonstrating an activity with different colored cellophane.

Hands-on Activity

What is the Habitable Zone?

Several cards on a table.

Art-infused Activity

Imagining Life