Sun Flashcards
Sun: Basic Facts
The Sun is a G-type main-sequence star (G2V) located at the center of our solar system, about 150 million km (1 AU) from Earth.
Sun: Composition
Made up of about 74% hydrogen, 24% helium, and 2% heavier elements such as oxygen, carbon, neon, and iron.
Sun: Energy Source
Energy is produced by nuclear fusion in the core, where hydrogen atoms combine to form helium, releasing enormous energy in the form of light and heat.
Layers of the Sun
The Sun has six main layers: Core, Radiative Zone, Convective Zone (internal layers); Photosphere, Chromosphere, and Corona (outer layers).
Core of the Sun
The innermost layer where nuclear fusion occurs, with temperatures reaching about 15 million Kelvin (K).
Radiative Zone
The region surrounding the core where energy is transferred outward via radiation, taking thousands to millions of years to pass through.
Convective Zone
The outermost layer of the Sun’s interior where heat is transferred by convection currents of hot plasma rising and cooler plasma sinking.
Photosphere
The visible surface of the Sun, about 5,500°C, where sunlight is emitted; sunspots appear in this layer.
Granules on the Sun
Small, bright convection cells (about 1,000 km wide) on the photosphere caused by hot plasma rising and cooler plasma sinking.
Supergranules
Larger convection patterns (~30,000 km wide) lasting 24 hours, transporting magnetic fields across the photosphere.
Chromosphere
A thin layer above the photosphere, visible during solar eclipses, appearing as a reddish glow due to ionized hydrogen (Hα emission).
Corona
The outermost atmosphere of the Sun, extending millions of kilometers into space, with temperatures exceeding 1 million K.
Solar Wind
A continuous stream of charged particles (mostly electrons and protons) flowing outward from the Sun, influencing space weather and Earth’s magnetosphere.
Sunspots
Dark, cooler regions on the photosphere caused by intense magnetic activity; appear in 11-year cycles.
Solar Flares
Sudden bursts of energy and radiation from the Sun’s surface, often near sunspots, releasing X-rays, ultraviolet light, and charged particles.
Coronal Mass Ejections (CMEs)
Massive bursts of plasma and magnetic fields from the corona, which can cause geomagnetic storms on Earth.
Solar Cycle
An approximately 11-year cycle of increasing and decreasing sunspot activity, affecting solar radiation and space weather.
Solar Minimum
The period in the solar cycle with the fewest sunspots, reduced solar activity, and lower space weather effects.
Solar Maximum
The peak of the solar cycle with the highest number of sunspots, increased solar flares, and stronger space weather effects.
Effects of Solar Activity on Earth
Solar storms can disrupt satellite communications, GPS, power grids, and create auroras (Northern and Southern Lights).
Heliosphere
The vast region of space influenced by the Sun’s solar wind, extending beyond Pluto and marking the boundary of the solar system.
Sun’s Role in Earth’s Climate
Variations in solar output can influence Earth’s climate, though human-induced factors have a much greater effect on global warming.
Future of the Sun
In about 5 billion years, the Sun will expand into a red giant, shed its outer layers, and eventually become a white dwarf.
Helioseismology
The study of the Sun’s internal structure and dynamics using observations of surface oscillations caused by pressure waves.
Solar Granulation
The mottled pattern seen on the Sun’s surface, caused by convection currents of hot plasma rising and cooler plasma sinking.
Magnetic Fields of the Sun
The Sun’s magnetic field is generated by the movement of charged particles in its interior, creating sunspots, solar flares, and coronal mass ejections.
Solar Dynamo
The process by which the Sun’s rotating, convecting plasma generates its magnetic field, leading to the 11-year solar cycle.
Plasma in the Sun
The Sun is made of plasma, a superheated, ionized gas where electrons and nuclei move freely, conducting electricity and generating magnetic fields.
Solar Neutrinos
Nearly massless particles produced in nuclear fusion reactions in the Sun’s core, providing insight into solar processes and fundamental physics.
Parker Solar Probe
A NASA mission launched in 2018 to study the Sun’s corona and solar wind up close, providing valuable data on solar activity.
Sun’s Differential Rotation
The Sun’s equator rotates faster (~25 days) than its poles (~35 days), causing complex magnetic field interactions.
Solar Energy and Earth’s Climate
Changes in solar output, known as solar irradiance, can influence Earth’s climate, but human activities have a greater impact on global warming.
Hale’s Polarity Law
A rule stating that sunspot pairs in one solar cycle have opposite magnetic polarity compared to those in the next cycle.
Solar Spectroscopy
The study of the Sun’s spectrum to determine its composition, temperature, motion, and magnetic activity.
Sun’s Light Travel Time to Earth
Light from the Sun takes about 8 minutes and 20 seconds to reach Earth, traveling at 300,000 km/s.
Solar Constant
The amount of solar energy received per square meter at Earth’s distance (~1361 W/m²). It fluctuates slightly due to the solar cycle.
Sun’s Role in Space Weather
The Sun’s activity influences space weather, affecting satellites, communication systems, astronauts, and power grids on Earth.
Sun’s Influence on Planetary Atmospheres
Solar radiation affects the atmospheres of planets, stripping away lighter gases from bodies with weak magnetic fields (e.g., Mars).
