Heliophysics Big Idea 3.1

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.

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: Every magnet produces an invisible volume of influence around itself in space. When things made of metal or other magnets come close to this region of space, they feel a pull or a push from the magnet. Scientists call these invisible influences fields. You can make magnetic fields visible to the eye by using iron chips sprinkled on a piece of paper with a magnet underneath. Did you know that the Earth, as well as some other planets, has a magnetic field? There are even magnetic fields on the Sun!

Intermediate: Magnetic fields are regions around a magnetic material or a moving electric charge within which the force of magnetism acts. Some materials such as iron are strongly attracted by magnets while other materials such as copper are not attracted. Our sun is composed of an electrically-conducting plasma in which portions of the plasma are in rapid movement. Like electrical currents flowing in a wire, the solar plasma creates magnetic fields.

Advanced: Gravity always points in the direction of the matter producing it. On Earth’s surface, this direction is towards the center of Earth. Magnetism depends on your location with respect to where the currents are located, and so the magnetic field has two poles called a North and South polarity. Depending on where you are located, the strength and direction of the field will vary. Magnetic fields store energy. To release it in a process called magnetic reconnection, opposing magnetic polarities have to be pushed into contact and compressed. This causes the magnetic field strength to increase, which causes currents to flow that then dissipate the magnetic energy as thermal and kinetic energy. If the magnetic fields are pushed together in a vacuum, however, no energy will be released since no intermediary plasma is present to form the necessary currents.

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: 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: 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: 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.

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: 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.