NASA is searching for evidence of life on other planets. What characteristics make life possible? Water is essential to all known forms of life on Earth. NASA scientists are looking for "Goldilocks Planets" that have temperatures not too hot or too cold to allow liquid water. By looking within our own solar system, we identify reasons neighboring planets and our moon lack conditions for life. Then we look at Earth: how the presence of liquid water, reflective surfaces such as polar ice caps, and the chemical composition of our atmosphere all contribute to keeping Earth's energy budget in balance.
A "Goldilocks Planet" is the right distance from its Sun to allow temperatures for liquid water. Not too hot, not too cold.
The Sun is our primary energy source. The energy Earth receives from the Sun is in balance with the energy our planet loses to space:
- Earth reflects an average 30% of incoming solar energy back to space
- Earth's atmosphere absorbs about 20% of incoming solar energy
- About 50% of solar energy reaches the land and oceans and warms them
- Earth emits 70% of incoming energy back to space as heat (infrared radiation)
NASA continuously monitors Earth using sensors on satellites, aircraft, and in situ instruments as there is still a lot to learn about the processes that support life on Earth.
Venus is too close to the Sun with an atmosphere that is mostly carbon dioxide, thus it is much too hot for water.
Mars is the right distance from the Sun, but does not have enough atmosphere and gets too cold at night. Water is frozen in polar ice caps. Curiosity rover is on Mars collecting samples and has found water in rock, but so far no evidence of life.
Our moon is the right distance from the Sun, but without an atmosphere it is too hot in the day and too cold at night.
This movie gives an overview of NASA's Search for Goldilocks Planets and can be used on its own or within a docent show as an introduction. The docent show covers Earth's energy budget in greater depth. You can find a script for the docent show here.
C3 Scale Proportion and Quantity. Students recognize natural objects and observable phenomena exist from the very small to the immensely large. They use standard units to measure and describe physical quantities such as weight, time, temperature, and volume.
C4 Systems and System Models. Students understand that a system is a group of related parts that make up a whole and can carry out functions its individual parts cannot. They can also describe a system in terms of its components and their interactions.
C5 Energy and Matter. Students learn matter is made of particles and energy can be transferred in various ways and between objects. Students observe the conservation of matter by tracking matter flows and cycles before and after processes and recognizing the total weight of substances does not change.
C7 Stability and Change. Students measure change in terms of differences over time, and observe that change may occur at different rates. Students learn some systems appear stable, but over long periods of time they will eventually change.
C1 Patterns. Students recognize that macroscopic patterns are related to the nature of microscopic and atomic-level structure. They identify patterns in rates of change and other numerical relationships that provide information about natural and human designed systems. They use patterns to identify cause and effect relationships, and use graphs and charts to identify patterns in data.
C2 Cause and Effect. Students classify relationships as causal or correlational, and recognize that correlation does not necessarily imply causation. They use cause and effect relationships to predict phenomena in natural or designed systems. They also understand that phenomena may have more than one cause, and some cause and effect relationships in systems can only be described using probability.
C4 Systems and System Models. Students can understand that systems may interact with other systems; they may have sub-systems and be a part of larger complex systems. They can use models to represent systems and their interactions—such as inputs, processes and outputs—and energy, matter, and information flows within systems. They can also learn that models are limited in that they only represent certain aspects of the system under study.
C5 Energy and Matter. Students learn matter is conserved because atoms are conserved in physical and chemical processes. They also learn within a natural or designed system, the transfer of energy drives the motion and/or cycling of matter. Energy may take different forms (e.g. energy in fields, thermal energy, energy of motion). The transfer of energy can be tracked as energy flows through a designed or natural system.
C7 Stability and Change. Students explain stability and change in natural or designed systems by examining changes over time, and considering forces at different scales, including the atomic scale. Students learn changes in one part of a system might cause large changes in another part, systems in dynamic equilibrium are stable due to a balance of feedback mechanisms, and stability might be disturbed by either sudden events or gradual changes that accumulate over time
C1 Patterns. Students observe patterns in systems at different scales and cite patterns as empirical evidence for causality in supporting their explanations of phenomena. They recognize classifications or explanations used at one scale may not be useful or need revision using a different scale; thus requiring improved investigations and experiments. They use mathematical representations to identify certain patterns and analyze patterns of performance in order to re-engineer and improve a designed system.
C7 Stability and Change. Students understand much of science deals with constructing explanations of how things change and how they remain stable. They quantify and model changes in systems over very short or very long periods of time. They see some changes are irreversible, and negative feedback can stabilize a system, while positive feedback can destabilize it. They recognize systems can be designed for greater or lesser stability
ESS1.A The Universe and its Stars. Stars range greatly in size and distance from Earth and this can explain their relative brightness.
ESS1.B Earth and the Solar System. The Earth’s orbit and rotation, and the orbit of the moon around the Earth cause observable patterns.
ESS1.C The History of Planet Earth. Certain features on Earth can be used to order events that have occurred in a landscape.
ESS2.A Earth Materials and Systems. Four major Earth systems interact. Rainfall helps to shape the land and affects the types of living things found in a region. Water, ice, wind, organisms, and gravity break rocks, soils, and sediments into smaller pieces and move them around
ESS2.C The Roles of Water in Earth's Processes. Most of Earth’s water is in the ocean and much of the Earth’s fresh water is in glaciers or underground.
ESS1.A The Universe and its Stars. The universe began with a period of extreme and rapid expansion known as the Big Bang. Earth and its solar system are part of the Milky Way galaxy, which is one of many galaxies in the universe.
ESS1.B Earth and the Solar System. The solar system contains many varied objects held together by gravity. Solar system models explain and predict eclipses, tides, lunar phases, and seasons.
ESS1.C The History of Planet Earth. Rock strata and the fossil record can be used as evidence to organize the relative occurrence of major historical events in Earth’s history.
ESS2.A Earth Materials and Systems. Energy flows and matter cycles within and among Earth’s systems, including the sun and Earth’s interior as primary energy sources. Plate tectonics is one result of these processes.
ESS2.C The Roles of Water in Earth's Processes. Water cycles among land, ocean, and atmosphere, and is propelled by sunlight and gravity. Density variations of sea water drive interconnected ocean currents. Water movement causes weathering and erosion, changing landscape features.
PS3.A Definitions of Energy. Kinetic energy can be distinguished from the various forms of potential energy. Energy changes to and from each type can be tracked through physical or chemical interactions. The relationship between the temperature and the total energy of a system depends on the types, states, and amounts of matter.
PS3.B Conservation of Energy and Energy Transfer. Kinetic energy can be distinguished from the various forms of potential energy. Energy changes to and from each type can be tracked through physical or chemical interactions. The relationship between the temperature and the total energy of a system depends on the types, states, and amounts of matter.
ESS1.A The Universe and its Stars. The sun is just one of more than 200 billion stars in the Milky Way galaxy, and the Milky Way is just one of hundreds of billions of galaxies in the universe. The study of stars’ light spectra and brightness is used to identify compositional elements of stars, their movements, and their distances from Earth.
ESS1.B Earth and the Solar System. Kepler’s laws describe common features of the motions of orbiting objects. Observations from astronomy and space probes provide evidence for explanations of solar system formation. Changes in Earth’s tilt and orbit cause climate changes such as Ice Ages
ESS1.C The History of Planet Earth. The rock record resulting from tectonic and other geoscience processes as well as objects from the solar system can provide evidence of Earth’s early history and the relative ages of major geologic formations.
ESS2.A Earth Materials and Systems. Feedback effects exist within and among Earth’s systems.The geological record shows that changes to global and regional climate can be caused by interactions among changes in the sun’s energy output or Earth’s orbit, tectonic events, ocean circulation, volcanic activity, glaciers, vegetation, and human activities.
ESS2.C The Roles of Water in Earth's Processes. The planet’s dynamics are greatly influenced by water’s unique chemical and physical properties.
PS3.A Definitions of Energy. The total energy within a system is conserved. Energy transfer within and between systems can be described and predicted in terms of energy associated with the motion or configuration of particles (objects).
PS3.B Conservation of Energy and Energy Transfer. Systems move toward stable states.