Inside the Sun
Name the three interior layers in order from the center outward.
Core → Radiative zone → Convection zone.
Which layer of the Sun do we see in visible light?
Photosphere
What are the Sun's top two elements and their approximate percentages?
Hydrogen (~74% by mass) and Helium (~24% by mass) (approximate; heavier elements ≈2%).
How long is the solar cycle and what happens to the magnetic field at maximum?
~11 years (magnetic polarity flips at maximum)
Name the three types of space weather phenomena.
Solar flares, coronal mass ejections (CMEs), and the solar wind
Why does energy take roughly 100,000 years to cross the radiative zone?
Photons undergo countless absorptions/scatterings in a dense plasma
Why do sunspots appear dark?
Sunspots are cooler due to concentrated magnetic fields so they emit less visible light and appear dark.
How does spectroscopy let us determine the composition of objects we can't sample?
Spectroscopy identifies characteristic absorption/emission lines tied to electron transitions; line wavelengths map to elements and relative line strengths yield abundances/conditions.
What is differential rotation and what does it do to the Sun's magnetic field?
Differential rotation (equator rotates faster than poles) stretches and twists magnetic field lines, amplifying complexity and leading to sunspot/active-region formation.
What's the difference between a solar flare and a CME?
Solar flares = sudden electromagnetic/X-ray bursts (nearly instantaneous radiation effects); CMEs = large magnetized plasma ejections that travel outward and can cause geomagnetic storms on arrival.
What is hydrostatic equilibrium, and why is it significant for the interior of the Sun?
Hydrostatic equilibrium = pressure gradient outward balances gravity inward. If it fails locally, material moves until a new balance is found; global balance prevents collapse or uncontrolled expansion.
You observe a bright active region in x-ray images of the corona. Where would you expect to find a corresponding feature in visible-light images, and why?
Sunspots - increased magnetic field activity
Before Payne-Gaposchkin, astronomers assumed the Sun matched Earth's crust composition. What did her analysis show, and why did it matter?
Payne-Gaposchkin showed hydrogen and helium dominate the Sun, overturning the Earth-crust analogy; this revealed stars are mostly H/He and enabled nuclear-fusion energy models.
Solar minimum is approaching. Predict what happens to: (a) number of sunspots, (b) flare frequency, (c) total radiation output.
(a) Sunspots decrease toward minimum. (b) Flare frequency decreases. (c) Total radiation (solar constant) changes very little — only slight variation (but it does decrease slightly)
What is the solar wind, where does it originate, and what mild effect does it cause on Earth?
Solar wind is a continuous outflow of charged particles from the corona, originating in coronal holes and the hot corona; it causes mild geomagnetic activity and the auroral oval to expand slightly, plus steady space-weather background effects.
Describe the process of energy transfer within the Sun's core to the outer layers.
Energy flows outward: core → radiative zone by photon absorption/scallering, then convection zone by bulk plasma motion in convection currents.
What are spicules, where are they found, and what might they help explain?
Spicules are short-lived, jet-like plasma features in the chromosphere seen at limb edges; they may channel mass/energy upward and help explain chromospheric heating or mass supply to the corona.
Roughly how many Earths could fit across the Sun's diameter, and how many could fit in its volume?
Diameter: ~100 Earths across. Volume: roughly 1 million Earths could fit inside the Sun.
What are the defining characteristics of solar maximum vs. solar minimum?
Solar maximum = many sunspots, high flare/CME activity, small increases in some wavelengths of output; solar minimum = few sunspots, low flare activity, near-baseline total radiation.
A radio blackout hits GPS and communications on Earth's day side with almost no warning, and 2–3 days later auroras appear at unusually low latitudes. Explain the sequence of two events that caused this.
(1) Solar flare produces immediate X-ray/UV causing dayside radio blackouts. (2) Associated CME arrives 1–3 days later, interacts with the magnetosphere to produce geomagnetic storms and low-latitude auroras.
During a total solar eclipse, which two layers become visible that are normally hidden?
During a total solar eclipse the chromosphere and corona become visible because the photosphere is blocked.
Order these three phenomena by the travel time of their effects to Earth (fastest to slowest) and state what each affects when it arrives: solar flare radiation, solar wind, a CME. Then explain why flare effects arrive with almost no warning but CME effects can be forecast days ahead.
Travel-time order (fastest→slowest): solar flare radiation (light/X-rays: arrives in ~8 minutes), solar wind (hours–days, steady stream), CME (hours→days depending on speed; often 1–3 days). Flare effects arrive almost instantly because they are electromagnetic radiation; CMEs are bulk plasma that must travel through interplanetary space so they can be observed and predicted days ahead.