Communicating Heliophysics at Different Levels

Glowing auroras are the result of millions of individual particle collisions, lighting up Earth's magnetic field lines.

Auroras are a brilliant display of light in the night sky. The aurora borealis and aurora australis—also known as the northern and southern lights—occur mainly near Earth's poles. When the solar wind reaches Earth's magnetosphere, it can send charged particles trapped in Earth’s magnetic field raining down toward Earth's poles, driven by a powerful process called magnetic reconnection. Along the way, particles can collide with atoms and molecules in Earth's upper atmosphere, which provides the atoms with extra energy that they release as a burst of light. These interactions continue at lower and lower altitudes until all the excess energy is lost. Studying auroras offers insights on how our magnetosphere reacts to near-Earth space weather.

What should learners know about this topic at each level?

Introductory: The biosphere includes all life on Earth, from the roots of plants to humans, from ocean depths to mountaintops. Plants, animals and human beings need the Sun in order to live. The Sun gives of light and produces energy.

Intermediate: The biosphere supports almost every aspect of human well-being and distinguishes Earth from other planets in our solar system. NASA data have changed the way we study life on Earth. Data on vegetation health, primary productivity, evapotranspiration, forest structure, and ocean chlorophyll provide insight into the health and productivity of the biosphere. The Sun is the only star we know of that supports a planet with a biosphere.

Advanced: During the daytime, X-rays and extreme ultraviolet rays from the Sun and galactic cosmic rays ionize Earth’s upper atmosphere, creating Earth’s ionosphere; the largest daytime contribution is from high-energy electromagnetic radiation from the Sun. At night, only cosmic rays ionize Earth’s upper atmosphere to create the ionosphere. The definition of “habitable zone” is the distance from a star at which liquid water could exist on orbiting planets’ surfaces. This is where conditions might be just right – neither too hot nor too cold – for life. While Venus, Earth, and Mars exist within the habitable zone around the Sun, only the conditions and ingredients on Earth allowed for life to evolve and flourish, most importantly the presence of water.

What should learners know about this topic at each level?

Introductory: Natural climate change has been going on since the dawn of Earth's history as landmasses have moved around, volcanoes have emitted gases into the atmosphere, and as the distance between the Sun and earth have changed over the eons. Today, human activity has had a noticeable change in our climate that has accelerated since the 1800s due to fossil fuel burning.

Intermediate: Scientists attribute the global warming trend observed since the mid-20th century to the human expansion of the "greenhouse effect" — warming that results when the atmosphere traps heat radiating from Earth toward space. Over the last century, burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2). This increase happens because the coal or oil burning process combines carbon with oxygen in the air to make CO2.

Advanced: Greenhouse gases are part of Earth's atmosphere and consist of carbon dioxide, methane, ozone, nitrous oxide, chlorofluorocarbons, and water vapor. Part of what makes Earth so amenable is its natural greenhouse effect, which maintains an average temperature of 15 °C (59 °F) . However, in the last century, human activities, primarily from burning fossil fuels that have led to the release of carbon dioxide and other greenhouse gases into the atmosphere, have disrupted Earth's energy balance. This has led to an increase in carbon dioxide in the atmosphere and ocean. The level of carbon dioxide in Earth’s atmosphere has been rising consistently for decades and traps extra heat near Earth's surface, causing temperatures to rise.

What should learners know about this topic at each level?

Introductory: The rising of warm air and the sinking of cool air. It can also be seen in a pot of boiling water.

Intermediate: Heat mixes and moves air. When a layer of air receives enough heat from the Earth's surface, it expands and moves upward. Colder, heavier air flows under it which is then warmed, expands, and rises. The warm rising air cools as it reaches higher, cooler regions of the atmosphere and begins to sink. Convectioncauses local breezes, winds, and thunderstorms. Convection also occurs in the Sun, where convection currents help move energy from the core of the Sun to its surface.

Advanced: Convection on the sun occurs in the outer 30% of the solar interior and extends all the way to the surface. Heated plasma at the base of the convection zone becomes bouyant and rises towards cooler regions at the photosphere. As the plasma cools it becomes more dense and then begins to fall back inwards under the force of gravity and become warmer and less dense. The cycle then repeats producing rolling convection cells. This process occurs in an electrically-charged plasma whose motions generate the solar magnetic field in the photosphere and corona.

The Sun's upper atmosphere is called the corona.

Introductory: The Sun has layers like an onion. The outer layer is called the corona. The Sun's energy is created in the core and travels outward through the corona and into space.

Intermediate:  The corona is the outer atmosphere of the Sun. The Sun has six major regions: the core, radiative zone, convective zone, photosphere, chromosphere, and corona. The Sun’s layered regions are marked by changes in density, from the highest density in the core to the lowest density in the corona. Temperatures in the corona can reach up to millions of degrees. The corona is the source of the solar wind as well as solar flares and coronal mass ejections – the energetic solar eruptions that create the strongest space weather. 

Advanced:  The corona is filled with plasma, whose movements are governed by the tangle of magnetic fields surrounding the Sun. It emits energy primarily as ultraviolet light. The Sun’s atmosphere blows out into the solar system as a stream of charged particles called the “solar wind.” Strong, dynamic magnetic fields on the Sun cause sunspots, solar flares, prominences, and coronal mass ejections.

What should learners know about this topic at each level?

Introductory: Magnetic reconnection occurs across the universe, including on the Sun, near black holes, and around Earth. Particles launched by magnetic reconnection near Earth can travel down along magnetic field lines into the atmosphere, where they can spark auroras.

Intermediate: When magnetic field lines become mixed, they can explosively snap and realign, flinging away nearby particles at high speeds in a process called magnetic reconnection. Coronal mass ejections, or CMEs, are large clouds of solar plasma and embedded magnetic fields released into space after a solar eruption. They are created when smaller-sized fields reconnect together to form progressively larger ones that contain enough energy to be launched from the Sun.

Advanced: Coronal mass ejections, or CMEs, expand as they sweep through space, often measuring millions of miles across, and can collide with planetary magnetic fields. When directed at Earth, a CME can produce geomagnetic disturbances that ignite bright aurora, short-circuit satellites and power grids on Earth, or at their worst, even endanger astronauts in orbit. When launched from the Sun, CME magnetic fields at first become compressed, which causes the trapped particles such as protons to be accelerated to very high energies. These solar proton events produce radiation that is a severe hazard for astronauts in space.

What should learners know about this topic at each level?

Introductory: Electromagnetic energy travels in waves from very long radio waves to very short gamma rays. Humans can only see visitble light. When you tune your radio, watch TV, send a text message, or pop popcorn in a microwave oven, you are using electromagnetic energy. NASA's scientific instruments use the full range of the electromagnetic spectrum to study the Earth, the solar system, and the universe beyond.

Intermediate: Spectroscopy is the science of reading light to determine the size, distance, spin and chemical composition of distant objects in space. There are a great variety of electromagnetic waves: radio waves, microwaves, infrared waves, visible light, ultraviolet rays, X-rays, and gamma rays. These wavelengths vary from radio waves, the longest, to gamma rays, the shortest. The Sun emits all these types of electromagnetic waves, though in different amounts for various wavelengths. NASA spacecraft use spectrometers to study the composition, physical structure and electronic structure of matter at the atomic, molecular and macro scale, and over astronomical distances.

Advanced: Life is adapted to conditions on the Earth, including an intensity of electromagnetic waves from the Sun that allows water to be present in the liquid state. When electrically charged objects undergo a change in motion, they produce electromagnetic waves around them. Magnetic forces are very closely related to electric forces and are thought of as different aspects of a single electromagnetic force. Moving electrically charged objects produces magnetic forces and moving magnets produces electric forces. In empty space, all electromagnetic waves move at the same speed - the speed of light.

What should learners know about this topic at each level?

Introductory: Electrically-charged particles affect each other through a force called electromagnetism. It causes electric sparks to form as you shuffle across a carpet and touch a metal surface like a door knob. The magnetic properties of this force can be felt by using magnets to move some metal objects without touching them directly.

Intermediate: The Sun is a giant magnetic star, made of material that moves in concert with the laws of electromagnetism. The Sun is made of a super-hot, electrically charged gas called plasma. The plasma rotates creating complex magnetic fields. The Sun’s magnetic field is responsible for everything from the solar explosions that cause space weather on Earth – such as auroras – to the interplanetary magnetic field and solar wind through which our spacecraft must travel.

Advanced: An electric current passing through a wire can cause a magnetic field to form around it. A magnet that is rapidly passed across the wire can cause an electric current to flow. Moving plasma currents on the sun can create magnetic fields and these fields carried by convection currents can induce other currents to flow elsewhere. When opposite-polarity magnetic fields are pushed together in a plasma, they release the stored magnetic energy in a process known as magnetic reconnection. This energy can trigger solar flares and CMEs, and also heat thhe corona and cause the solar wind to flow.

What should learners know about this topic at each level?

Introductory: The Sun warms the land, air, and water because these materials absorbe the sunlight energy that falls upon them. Sunlight can be converted into electricity using solar panels as a way to run many devices.

Intermediate: There are a great variety of electromagnetic waves: radio waves, microwaves, infrared waves, visible light, ultraviolet rays, X-rays, and gamma rays. These wavelengths vary from radio waves, the longest, to gamma rays, the shortest. Energy in solar processes moves and changes form. Electrical energy can be generated from sunlight, and can be transformed into almost any other form of energy. Energy from the Sun is available indefinitely.

Advanced: Sunlight is the ultimate source of most of the energy we use. The energy in fossil fuels such as oil and coal comes from energy that plants captured from the Sun long ago. Solar panels absorbe sunlight and convert it directly into electricity. On the Sun, magnetic fields contain stored energy, which in a process called magnetic reconnection, can be released to heat up and accelerate local plasma.