The Sun and Solar Physics

A collection of vocabulary terms and key concepts covering the structure, energy production, atmospheric features, and activities of the sun.

Luminosity

The total power the sun emits as radiation, officially defined as $3.828 \times 10^{26}\,W$.

Solar constant

The average amount of solar radiation per unit area measured at the top of the Earth's atmosphere, equivalent to the energy received at a one square meter detector on the Earth's surface.

Differential rotation

A phenomenon occurring because the sun is a gaseous plasma, where the equator spins faster than the polar regions.

Photosphere

The visible surface of the sun that has an effective temperature of about $5,800\,K$.

Convection zone

The outermost layer of the solar interior which acts as a conveyor belt where hot plasma rises from the core, cools at the surface, and sinks.

Chromosphere

The reddish layer of the sun's atmosphere where temperatures rise to about $20,000^{\circ}C$.

Corona

The sun's outer atmosphere consisting of super hot plasma reaching temperatures of over $1,000,000^{\circ}C$, typically visible during total solar eclipses.

Stellar balance

A self regulating equilibrium that prevents a star from collapsing under its own weight or blowing apart by balancing gravity's compression with outward pressure from gas and radiation.

Granules

Bright polygonal cells about $1,000\,km$ across located on the photosphere that represent the tops of convection cells.

Absorption lines

Dark lines throughout the visible spectrum that produce a unique fingerprint pattern used to identify which of the $67$ elements are present in the sun.

Spicules

Dynamic jet like plumes of plasma in the chromosphere that shoot upward at speeds of $15$ to $110\,km/s$ and last about five to ten minutes.

Sunspots

Dark, cooler areas on the photosphere caused by concentrations of magnetic field lines that inhibit convection.

Solar prominences

Massive loop like structures anchored to the photosphere and composed of cool dense gas trapped by magnetic fields that can extend hundreds of thousands of kilometers into the corona.

Solar flare

Sudden intense explosions of light and energy across the electromagnetic spectrum that travel at the speed of light and are not anchored to the photosphere.

Coronal mass ejections

Physical clouds or bubbles of plasma and magnetic field expelled from the corona that can take over $15$ hours to arrive at Earth and cause geomagnetic storms.

Solar wind

A high speed stream of charged particles escaping through coronal holes at speeds over $1,600,000\,km/h$.

Nuclear fusion

The process in the sun's core where atomic nuclei combine to form a larger nucleus and convert leftover mass directly into energy.

$$e = m c^2$$

Einstein's equation representing the relationship between mass ($m$) and energy ($e$), where $c$ is the speed of light, showing that a small amount of mass is equivalent to a large amount of energy.

Deuteron

The nucleus of heavy hydrogen, or deuterium, consisting of one proton and one neutron bound together.

Positron

A particle that is the positive charge counterpart to an electron; they annihilate with electrons to transform their combined mass into gamma ray energy.

Neutrino

A neutral 'ghost particle' with an incredibly tiny mass that is emitted during the proton proton chain and escapes the sun a few seconds after being created.

Neutrino oscillations

The discovery made by the Sudbury Neutrino Observatory that neutrinos change type as they travel, solving the solar neutrino problem.