Sun Structure and Energy
Clue: This process in the Sun’s core combines hydrogen nuclei to form helium and release enormous amounts of energy.
Response: What is nuclear fusion?
Clue: These colorful displays, called Aurora Borealis in the north and Aurora Australis in the south, occur when charged solar particles interact with gases in Earth’s upper atmosphere.
Response: What are auroras?
Clue: Earth’s axis is tilted at approximately this angle, which is a primary reason Earth experiences seasons.
Response: What is 23.5?
Clue: This term means incoming solar radiation received by Earth.
Response: What is insolation?
Clue: This close alignment of the Sun, Earth, and Moon is required for an eclipse to occur.
Response: What is syzygy?
Clue: The Sun is composed of approximately 70% hydrogen, 28% helium, and 2% other elements, existing primarily in this state of matter made of electrically charged particles.
Response: What is plasma?
Clue: These darker, cooler areas on the photosphere result from strong concentrations of magnetic energy and follow an approximately 11-year cycle.
Response: What are sunspots?
Clue: This term describes Earth’s spinning on its axis, which takes approximately 24 hours and causes day and night.
Response: What is rotation?
Clue: This measurement describes distance north or south of the equator and influences the angle at which sunlight strikes Earth’s surface.
Response: What is latitude?
Clue: During this type of eclipse, Earth moves between the Sun and Moon, blocking sunlight from reaching the Moon.
Response: What is a lunar eclipse?
Clue: This balance between the inward pull of gravity and the outward pressure produced by hot gases and fusion keeps the Sun stable.
Response: What is hydrostatic equilibrium?
Clue: This continuous stream of charged particles flows outward from the Sun and may take several days to reach Earth.
Response: What is solar wind?
Clue: These two events occur when day and night are nearly equal in length around Earth, generally around March and September.
Response: What are equinoxes?
Clue: Locations near the equator are at approximately this latitude and generally receive more direct sunlight throughout the year.
Response: What is 0 latitude?
Clue: This is the darkest central part of a shadow, where light is completely blocked.
Response: What is the umbra?
Clue: Energy moves through this layer mainly by radiation, often being absorbed and re-released by particles many times.
Response: What is the radiative zone?
Clue: This large loop or arc of glowing plasma extends above the Sun’s surface and is held in place by magnetic fields.
Clue: This large loop or arc of glowing plasma extends above the Sun’s surface and is held in place by magnetic fields.
Response: What is a prominence?
Clue: Earth reaches this point in its orbit in early January, when it is closest to the Sun.
Response: What is perihelion?
Clue: When sunlight strikes Earth’s surface at a low angle, the same energy is spread over this kind of area, reducing the heating received by each part of the surface.
Response: What is a larger area?
Clue: During a total lunar eclipse, Earth’s atmosphere scatters more blue light and bends more of this color of light into Earth’s shadow, making the Moon appear reddish.
Response: What is red light?
Clue: This process creates new elements inside stars. The Sun currently changes hydrogen into helium, while larger stars can create elements such as carbon, oxygen, and iron.
Response: What is nucleosynthesis?
Clue: Unlike a solar flare, which is mainly a burst of light and radiation, this event releases a huge cloud of charged particles and magnetic energy from the corona.
Response: What is a coronal mass ejection, or CME?
Clue: This slow change in the direction Earth’s axis points traces a large circle over approximately 26,000 years.
Response: What is precession?
Clue: Sunlight is usually most direct at this time of day, when the Sun reaches its highest apparent position in the sky.
Response: What is solar noon?
Clue: Solar eclipses are visible from a smaller area than lunar eclipses because the Moon’s shadow has this effect on Earth.
Response: What is: the Moon’s shadow covers only a small portion of Earth’s surface?
Clue: Detailed solar diagrams identify this boundary layer between the radiative zone and the convection zone.
Response: What is the tachocline?
Clue: This region surrounding Earth is controlled by our planet’s magnetic field and helps deflect some charged particles from the solar wind and CMEs.
Response: What is the magnetosphere?
Clue: Explain why seasons are not primarily caused by Earth’s changing distance from the Sun. Include the timing of perihelion and aphelion in your response.
Response: What is: Earth is closest to the Sun at perihelion in early January, during Northern Hemisphere winter, and farthest from the Sun at aphelion in early July, during Northern Hemisphere summer? Therefore, axial tilt and the resulting changes in sunlight angle and daylight length—not distance—are the primary causes of seasons.
Clue: Identify the three major factors that affect the amount of insolation a location receives and explain how each affects surface heating.
Response: What are latitude, time of day, and season? Latitude affects the angle of incoming sunlight; sunlight is generally more direct near the equator. Time of day affects the Sun’s angle, with the most direct sunlight usually occurring around solar noon. Season affects both sunlight angle and daylight length because of Earth’s axial tilt.
Clue: Give the alignment sequence for both types of eclipses and explain why an observer in the Moon’s penumbra sees only a partial solar eclipse.
Response: What is: a solar eclipse has the alignment Sun → Moon → Earth, while a lunar eclipse has the alignment Sun → Earth → Moon? In the penumbra, the Moon blocks only part of the Sun’s disk from the observer’s location, so some sunlight remains visible.