Communicating Heliophysics at Different Levels

What should learners know about this topic at each level?

Introductory: Aurora are colored lights in the sky that appear over the Arctic Region (Aurora Borealis) and the Antarctic Region (Aurora Australis) during days when the Sun produces storms. These stormy periods follow the sunspot cycle and are most numerous when many sunspots are present.

Intermediate: Auroras are caused by currents of charged particles that are accelerated within Earth’s magnetosphere. These particles, usually electrons, follow Earth's magnetic field into the polar regions and cause atoms of oxygen and nitrogen to give off specific colors of light. Solar storms called coronal mass ejections or CMEs, interact with Earth's magnetosphere cause temporary disturbances in Earth's magnetosphere. These disturbances are called "geomagnetic storms."

Advanced: Glowing auroras are the result of millions of individual particle collisions, colliding with atoms of oxygen and nitrogen, and lighting up Earth's magnetic field lines over the Polar Regions. When CMEs reach Earth's magnetosphere, they can cause magnetic reconnection, which transfers magnetic energy into accelerating electrons in the magnetiosphere. This causes electrons trapped in Earth’s magnetic field to rain down toward Earth's poles. Along the way, these electrons can collide with atoms and molecules in Earth's upper atmosphere, which provides the atoms with extra energy, which 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. Convection causes 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.

What should learners know about this topic at each level?

Introductory: The Sun is a star, but seen up close by us. The Sun is the center of our Solar System and is the largest object in our Solar System. The Sun appears to have been active for 4.6 billion years and has enough fuel for another 5 billion years or so. The Sun has layers like an onion. The Sun is an above-average star in terms of mass, temperature, and size. Most of the stars in our galaxy are smaller, cooler, and less massive than our Sun.

Intermediate: Strong, dynamic magnetic fields on the Sun cause sunspots, solar flares, prominences, and coronal mass ejections. 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. At the end of its life, the Sun will start to fuse helium into heavier elements and begin to swell up, ultimately growing so large that it will swallow Earth. After a billion years as a ‘red giant,’ it will suddenly collapse into a ‘white dwarf.’ It may take a trillion years to cool off completely.

Advanced: Energy moves outward from the core through the radiative zone by way of electromagnetic radiation colliding with matter. Energy moves outward through the convection zone through “convection”: the rising of hot matter that cools and falls, heats up and rises again. The photosphere is a glowing shell of matter at the outer layer of the convection zone. It emits energy primarily as visible light. The chromosphere is a glowing shell of matter between the photosphere and corona. It emits energy primarily as ultraviolet light and is hotter than the photosphere. The corona is the outer atmosphere of the Sun. It emits energy primarily as ultraviolet light and is hotter than the chromosphere. The Sun’s atmosphere blows out into the Solar System as a stream of charged particles called the “solar wind.”

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: 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.

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 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: The solar wind is a flow of particles from the sun's corona that travels across interplanetary space and blows a bubble in the interstellar matter surrounding the solar system. Everything within the boundaries caused by these interactions is called the “heliosphere.”

Intermediate: The Sun has a magnetic field. The Sun emits a stream of charged particles called the solar wind. The Sun periodically sends out bursts of charged particles and electromagnetic energy so the solar wind varies. The Sun's magnetic field extends to the far reaches of the solar system. The heliosphere encloses all of the planets and is filled by the Sun’s plasma and magnetic field. In interstellar space outside the heliosphere, the interstellar medium and the galactic magnetic field are dominant. The heliosphere acts as a shield for our solar system, blocking many of the high-energy galactic cosmic rays from elsewhere in our galaxy. Of the spacecraft sent from Earth, only the twin Voyager spacecraft — traveling since 1977 — have been confirmed to have made it beyond the boundaries of the heliosphere.

Advanced: The solar wind causes chemical and electrical reactions on the surfaces of worlds without atmospheres or magnetospheres, like the Moon or asteroids. More energetic particles cause nuclear changes. The solar wind strips away the atmospheres of some planets without large-scale magnetospheres. The solar wind affects the shape of magnetospheres. The giant planets (Jupiter, Saturn, Uranus, Neptune) all have very strong magnetic fields that interact intensely with the solar wind. Worlds without a conducting liquid core (e.g. Mercury, Venus, our Moon, and Mars) do not have large-scale magnetic fields. Only local regions on their surfaces are partially protected from the solar wind by magnetic fields in their crustal rocks. The creation and variability of magnetic dynamos drive the dynamics of solar and stellar environments.

What should learners know about this topic at each level?

Introductory: Plasma is the most common, easily observable, state of matter in the universe. All stars, including our Sun, are made of plasma.

Intermediate: Plasma is a gas consisting of electrically charged particles, a state of matter distinct from solids, liquids and gases. Though rare on Earth, plasma makes up over 99% of the observable (i.e., not dark) matter in the universe, including every star, including our Sun, and much of the material between them. On Earth, plasma is found in fluorescent lights, torches used for metalworking, and lightning strikes. Plasma forms when the atoms in a gas become ionized, meaning electrons separate from the atom and move around independently. This makes plasmas electrically charged and they can interact with external electric and magnetic fields. They can also create their own electric and magnetic fields. Plasmas also undergo an explosive process called magnetic reconnection. Magnetic reconnection is a rapid transfer of magnetic energy into motion that powers solar flares and coronal mass ejections.

Advanced: Plasma processes accelerate and transport particles throughout the Sun and the solar system. The existence of charged particles causes plasma to generate, and be affected by, magnetic fields. This can cause extremely complex dynamics. Under certain circumstances, plasmas cannot cross magnetic field lines, though they can slide along them like beads on an elastic string. As a result, a strong plasma can bend weak magnetic fields, and strong magnetic fields can hold back weak plasmas.

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: During a lunar eclipse, Earth comes between the Sun and the Moon, blocking the sunlight falling on the Moon.

Intermediate: When the Moon is entirely in the Earth's umbra (known as a total lunar eclipse or umbral eclipse), all sunlight reaching the lunar surface has been refracted or scattered through Earth's atmosphere. When the Moon is in Earth's penumbra (known as a penumbral eclipse), illumination comes from both direct sunlight and sunlight refracted and scattered through the planet's atmosphere. During some stages of a lunar eclipse, the Moon can appear reddish. This is because the only remaining sunlight reaching the Moon at that point is from around the edges of the Earth, as seen from the Moon's surface.

Advanced: The Moon moves into the inner part of Earth’s shadow, or the umbra. Some of the sunlight passing through Earth’s atmosphere reaches the Moon’s surface, lighting it dimly. Colors with shorter wavelengths ― the blues and violets ― scatter more easily than colors with longer wavelengths, like red and orange. Because these longer wavelengths make it through Earth’s atmosphere, and the shorter wavelengths have scattered away, the Moon appears orangish or reddish during a lunar eclipse. The more dust or clouds in Earth’s atmosphere during the eclipse, the redder the Moon appears.

What should learners know about this topic at each level?

Introductory: The only object in the solar system that shines with its own light is the Sun. A very small portion of this light is directed towards Earth and the moon, illuminating the daytime-half of our planet in its orbit and reflecting off the surface of the Moon to create moonlight.

Intermediate: Like Earth, the Moon has a day side and a night side, which change as the Moon rotates. The Sun always illuminates half of the Moon while the other half remains dark, but how much we are able to see of that illuminated half changes as the Moon travels through its orbit. When sunlight hits off the Moon's far side — the side we can't see without from Earth the aid of a spacecraft — it is called anew Moon. When sunlight reflects off the near side, we call it a full Moon. The rest of the month we see parts of the daytime side of the Moon, or phases. These eight phases are, in order, new Moon, waxing crescent, first quarter, waxing gibbous, full Moon, waning gibbous, third quarter and waning crescent. The cycle repeats once a month (every 29.5 days).

Advanced: One of the biggest misconceptions is that there is a 'dark side' of the moon. This cannot happen because the moon rotetes once upon its axis in the same number of days and hours as it orbits Earth. This has happened because when the moon was formed, became gravitationally 'locked' into this 1-to-1 spin-orbit resonance, which forces its 'day' and 'year' to be exactly equal. The Moon will always show exactly the same side towards Earth as a result. Mercury is in a slightly different 3-to-2 resonance where it rotates 3 times on its axis for every 2 orbits of the Sun.

What should learners know about this topic at each level?

ntroductory: 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: 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: Earth’s magnetic field is created deep within its core and extends out into space, just as the magnetic field of a toy magnet does. Within this magnetic field, charged particles are affected and feel a magnetic force as they move. This region of space near Earth, where Earth’s magnetic field controls the movement of matter is called the magnetosphere.

Intermediate: in our solar system, several planets, including Earth, and even one of Jupiter’s moons have magnetospheres. Magnetospheres of planets have a “teardrop” or ice cream cone shape, with a rounded, shorter end created as the Sun’s material pushes against the magnetic field and a long tail (magnetotail) trailing away on the other side. Like a windsock near a breezy airport runway, Earth’s magnetotail flaps back and forth in the gusty solar wind. The immense magnetotail of Earth fluctuates in length and can measure hundreds of Earth radii, far past the moon’s orbit at 60 Earth radii. Electric currents in the earth’s interior give the earth an extensive magnetic field, which we detect from the orientation of compass needles. The Earth’s magnetosphere shield our planet from some types of solar particles.

Advanced: A magnetosphere is formed when the solar wind interacts with and is deflected by the magnetic field of a planet or other body. Earth’s magnetic field is important for life on our planet. Earth’s space environment (ionosphere, upper atmosphere, and magnetosphere) changes with time, and understanding those changes helps us ease any negative effects those changes might have on Earth-based and space-based systems. Space explorers, both human and robotic, encounter extreme environments outside our magnetosphere and need to be able to adapt to them.

What should learners know about this topic at each level?

Introductory: All bodies attract each other with what is called gravitational attraction. This applies to the largest stars as well as the smallest particles of matter.

Intermediate: Gravity can be mathematically modeled and used to predict the motions of the sun, planets and other objects in the universe. Its strength was determined by Newton to follow an inverse-square Law such that if you double the distance between two bodies, the strength of te interaction diminished by a factor of four. The strength is also proportional to the product of the masses of the two bodies. Experiments and observations have confirmed this model for gravity from scales of a few centimeters, to the scale of galaxies and the universe.

Advanced: There are three fundamental forces in Nature called electromagnetism and the strong and weak nuclear interactions. Detailed quantum medchaanical models exist for these three interactions that depend on particles exchanging force-carrying particles that are unique to each force. Gravity, however, does not follow this pattern of having a force-carrier. According to Albert Einstein's theory of general relativiy, gravity is not a force at all. It is caused by the curvature of spacetime. This model for gravity has been successful in predicting black holes and the evolution of our 'Big Bang' universe.

What should learners know about this topic at each level?

Introductory: Nuclear fusion occurs in the core of the Sun and all stars. Immense pressures and temperatures in the star’s core squeeze the nuclei of hydrogen atoms together to form helium.

Intermediate: Nuclear fusion is a process that produces energy when two nuclei join to form a heavier nucleus. Nuclear fusion releases energy, which heats the star and prevents it from further collapsing under the force of gravity.

Advanced: Astronomers call stars that are stably undergoing nuclear fusion of hydrogen into helium main sequence stars. This is the longest phase of a star’s life. The star’s luminosity, size, and temperature will slowly change over millions or billions of years during this phase. Our Sun is roughly midway through its main sequence stage. A high-mass star goes further. Fusion converts carbon into heavier elements like oxygen, neon, and magnesium, which will become future fuel for the core.

What should learners know about this topic at each level?

Introductory: Plasma is the most common, easily observable, state of matter in the universe. All stars, including our Sun, are made of plasma.

Intermediate: Plasma is a gas consisting of electrically charged particles, a state of matter distinct from solids, liquids and gases. Though rare on Earth, plasma makes up over 99% of the observable (i.e., not dark) matter in the universe, including every star, including our Sun, and much of the material between them. On Earth, plasma is found in fluorescent lights, torches used for metalworking, and lightning strikes. Plasma forms when the atoms in a gas become ionized, meaning electrons separate from the atom and move around independently. This makes plasmas electrically charged and they can interact with external electric and magnetic fields. They can also create their own electric and magnetic fields. Plasmas also undergo an explosive process called magnetic reconnection. Magnetic reconnection is a rapid transfer of magnetic energy into motion that powers solar flares and coronal mass ejections.

Advanced: Plasma processes accelerate and transport particles throughout the Sun and the solar system. The existence of charged particles causes plasma to generate, and be affected by, magnetic fields. This can cause extremely complex dynamics. Under certain circumstances, plasmas cannot cross magnetic field lines, though they can slide along them like beads on an elastic string. As a result, a strong plasma can bend weak magnetic fields, and strong magnetic fields can hold back weak plasmas.

What should learners know about this topic at each level?

Introductory: Outside the protective cocoon of the Earth’s atmosphere is a universe full of radiation – it is all around us. Radiation can be created by humans (microwaves, cell phones, radios, light bulbs, diagnostic medical applications such as x-rays) or naturally occurring.

Intermediate: Radiation is a form of energy that is emitted in the form of rays, electromagnetic waves, and/or particles. Most of the radiation that the Sun emits is in the form of visible light. Energy appears in different forms and can be transformed and transported within the Sun’s system.

Advanced: Naturally occuring sources of radiation are the Sun, radioactive elements in the Earth’s crust, radiation trapped in the Earth’s magnetic field, stars, and other astrophysical objects like quasars or galactic centers). In some cases, radiation can be seen (visible light) or felt (infrared radiation), while other forms—like x-rays and gamma rays—are not visible and can only be observed with special equipment. Space radiation is different from the kinds of radiation we experience here on Earth. Space radiation is comprised of atoms in which electrons have been stripped away as the atom accelerated in interstellar space to speeds approaching the speed of light – eventually, only the nucleus of the atom remains.

What should learners know about this topic at each level?

Introductory: We can only see the Sun in the daytime. The Sun appears to move slowly across the sky during the day. Light from the sun is made up of a mixture of many different colors of light, even though to the eye the light looks white.

Intermediate: The rotation of Earth on its axis every 24 hours produces the night-and-day cycle. To people on Earth, this turning of the planet makes it seem as though the Sun orbits the Earth once a day. The Earth orbits the Sun, and the Moon orbits the Earth. The number of hours of daylight and the intensity of the sunlight both vary in a predictable pattern that depends on how far north or south of the equator the place is. This variation explains why temperatures vary over the course of the year and at different locations.

Advanced: Because the Earth turns daily on an axis that is tilted relative to the plane of the Earth's yearly orbit around the Sun, sunlight falls more intensely on different parts of the Earth during the year. The difference in intensity of sunlight and the resulting warming of the Earth's surface produces the seasonal variations in temperature.

What should learners know about this topic at each level?

Introductory: The number of sunspots on the sun’s visible surface increase and decrease over time in a regular, approximately 11-year cycle, called the sunspot or solar cycle.

Intermediate: The exact length of the solar cycle can vary. It has been as short as eight years and as long as fourteen, but the number of sunspots always increases over time, and then returns to low again. More sunspots mean increased solar activity, when great blooms of radiation known as solar flares or bursts of solar material known as coronal mass ejections (CMEs) shoot off the sun’s surface.

Advanced: The highest number of sunspots in any given cycle is designated “solar maximum,” while the lowest number is designated “solar minimum.” Each solar cycle, varies dramatically in intensity, with some solar maxima being so low as to be almost indistinguishable from the preceding minimum. Many other stars have been observed to have ‘sunspot’ cycles as well. These can be as short as a few years or as long a several decades. The reason for the precise period length and intensity seems to be rooted in the flows of plasma just below the solar surface called the tachocline. These currents, like ocean currents on Earth, flow from the equator to the poles, dive below the surface and return to the equatorial zone completing a full sunspot cycle.

What should learners know about this topic at each level?

Introductory: Space weather refers to conditions in space produced by the Sun’s activity. Prediction of space weather helps to protect human in space, technology, communications, and power systems on Earth. Solar flares are the most powerful explosions in the solar system. The energetic particles accelerated by flares travel nearly at the speed of light, and can travel the 93 million miles between the Sun and Earth in less than 20 minutes.

Intermediate: A geomagnetic storm is a major disturbance of Earth’s magnetosphere that occurs when there is a very efficient exchange of energy from the solar wind and coronal mass ejections into the space environment surrounding Earth. Space weather is the interaction of matter and energy from the Sun with magnetic fields such as Earth’s. Radio blackouts occur when the strong, sudden burst of x-rays from a solar flare hits Earth’s atmosphere, disturbing high and low frequency waves in the ionosphere. The loss of low frequency radio communication causes GPS measurements to be off by feet to miles, and can also affect the applications that govern satellite positioning.

Advanced: Variable features of the Sun due to strong, dynamic magnetic fields include sunspots, solar flares, prominences, and coronal mass ejections (CMEs). These processes occur on a variety of time scales, from minutes to years. Solar flares are energetic bursts of light and particles triggered by the release of magnetic energy on the Sun. Geomagnetic storms result from variations in the solar wind that produces major changes in the currents, plasmas, and fields in Earth’s magnetosphere. The solar wind conditions that are effective for creating geomagnetic storms are sustained (for several to many hours) periods of high-speed solar wind, and most importantly, a southward directed solar wind magnetic field (opposite the direction of Earth’s field) at the dayside of the magnetosphere. This condition is effective for transferring energy from the solar wind into Earth’s magnetosphere.
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What should learners know about this topic at each level?

Introductory: The solar system has one star, eight planets, five officially named dwarf planets, hundreds of moons, thousands of comets, and more than a million asteroids.

Intermediate: There are many planetary systems like ours in the universe, with planets orbiting a host star. Our planetary system is called “the solar system” because we use the word “solar” to describe things related to our star, after the Latin word for Sun, "solis." Our solar system consists of our star, the Sun, and everything bound to it by gravity – the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune; dwarf planets such as Pluto; dozens of moons; and millions of asteroids, comets, and meteoroids.

Advanced: The discovery of planets orbiting other stars, called exoplanets, now numbr over 5,000 and are fiund in over 4,000 distinct 'exoplanet systems' .Amazingly, none of these look like our own solar systems in terms of the kinds of planets and their distances from their stars. Astronomers still do not understand exactly why exoplanets in other planetary systems look so different from our own planets, although twins to our palnets have been found in numerous other systems.

What should learners know about this topic at each level?

Introductory: The solar wind is a gusty stream of material that flows from the Sun in all directions, all the time, carrying the Sun’s magnetic field out into space.

Intermediate: While it is much less dense than wind on Earth, solar wind is much faster, typically blowing at speeds of one to two million miles per hour. The solar wind is made of charged particles — electrons and ionized atoms — that interact with each other and the Sun’s magnetic field. The extent of the solar wind creates the heliosphere, the Sun’s region of influence within interstellar space.

Advanced: The origin of the solar wind seems to be in the corona of the sun where magnetic fields are ‘reconnecting’ and depositing energy into the coronal plasma. This plasma becomes hot enough to escape the gravitational influence of the Sun and flow out into interplanetary space.

What should learners know about this topic at each level?

Introductory: Space weather refers to conditions in space produced by the Sun’s activity. Prediction of space weather helps to protect human in space, technology, communications, and power systems on Earth. Solar flares are the most powerful explosions in the solar system. The energetic particles accelerated by flares travel nearly at the speed of light, and can travel the 93 million miles between the Sun and Earth in less than 20 minutes.

Intermediate: A geomagnetic storm is a major disturbance of Earth’s magnetosphere that occurs when there is a very efficient exchange of energy from the solar wind and coronal mass ejections into the space environment surrounding Earth. Space weather is the interaction of matter and energy from the Sun with magnetic fields such as Earth’s. Radio blackouts occur when the strong, sudden burst of x-rays from a solar flare hits Earth’s atmosphere, disturbing high and low frequency waves in the ionosphere. The loss of low frequency radio communication causes GPS measurements to be off by feet to miles, and can also affect the applications that govern satellite positioning.

Advanced: Variable features of the Sun due to strong, dynamic magnetic fields include sunspots, solar flares, prominences, and coronal mass ejections (CMEs). These processes occur on a variety of time scales, from minutes to years. Solar flares are energetic bursts of light and particles triggered by the release of magnetic energy on the Sun. Geomagnetic storms result from variations in the solar wind that produces major changes in the currents, plasmas, and fields in Earth’s magnetosphere. The solar wind conditions that are effective for creating geomagnetic storms are sustained (for several to many hours) periods of high-speed solar wind, and most importantly, a southward directed solar wind magnetic field (opposite the direction of Earth’s field) at the dayside of the magnetosphere. This condition is effective for transferring energy from the solar wind into Earth’s magnetosphere.

What should learners know about this topic at each level?

Introductory: A star is born, lives, and dies, much like everything else in nature. Stars are giant balls of hot plasma – mostly hydrogen, with some helium and small amounts of other elements. Every star has its own life span, ranging from a few million to trillions of years.

Intermediate: The properties of a star change as it ages. The fate and life of a star depends primarily on its mass. Astronomers estimate that the universe could contain up to one septillion stars – that’s a one followed by 24 zeros. Our Milky Way alone contains more than 200 billion, including our most well-studied star, the Sun.

Advanced: Stars reach their end-stages in a variety of 'graveyard' forms from white dwarfs for our sun, to neutron styars for massive stars, and even black holes for the most massive stars. Low-mass stars like our sun enter their final stages non-explosively, but massive stars more than 8 times our sun usually become supernovae. These supernovae explosions can be seen across the entire 14 billion light years of the visible universe. They also eject matter into interstellar space that is enriched with elements heavier than helium, and are the principle reason why carbon-based life exists in this universe.

What should learners know about this topic at each level?

ntroductory: Sunspots are cooler regions on the Sun that for the largest ones you can see them from Earth without a telescope if you safely filter your eyes.

Intermediate: The Sun has dark spots, called “sunspots” caused by a concentration of magnetic field lines. Sunspots are slightly cooler regions on the Sun’s surface. Sunspots last from days to weeks. Lasting from days to months, sunspots typically stretch 1,000 to 100,000 miles across. The number of sunspots goes up and down as the Sun goes through its natural 11-year cycle. Scientists use sunspots to help them track this cycle.

Advanced: The convective movement of the plasma on the solar surface can drag magnetic fields with them and concentrate them. This causes the field to be amplified, which prevents plasma from below these fields from transporting their energy to the surface. As a result, these magnetic concentrations sit on top of cooler plasma regions and so appear darker compared to the surrounding 5600 k photosphere.

What should learners know about this topic at each level?

Introductory: A transit happens when one body in the sky crosses in front of another from our point of view.

Intermediate: Eclipses are a type of transit. On Earth, we most often see Mercury transit the Sun, or – even more rarely – Venus (2012, 2117, 2125). Transits are also one of the primary ways scientists look for evidence of exoplanets, planets beyond our solar system. As exoplanets pass between their host star and Earth, the light we measure from the host star decreases slightly, giving scientists clues about the planet or planets that may be orbiting that star.

Advanced: Edmund Halley proposed the idea of using transits of Venus to measure the size of the solar system in 1716 when he published a paper outlining how to utilize the upcoming transits of Venus in 1761 and 1769 to calculate the Earth's distance from the Sun, known as the astronomical unit. Halley realized that by observing a transit of Venus from different locations on Earth, the apparent path of Venus across the Sun would appear slightly different due to parallax, allowing for distance calculations.