Properties of the Sun Visual Vocabulary

LEARNING OBJECTIVES: SC.912.E.5.4: Explain the physical properties of the Sun and its dynamic nature and connect them to conditions and events on Earth

Sun The Sun gives life to the Earth and the Earth would have no life at all without the energy it receives from the Sun. The Sun is only one of millions and millions of stars in the Galaxy. Like all stars, the Sun is composed of a great burning ball of gases. It is made of 92.1% hydrogen and 7.8% helium (helium is from the ancient Greek word helios, which means Sun).

Sunspots Sunspots are darker, cooler areas on the surface of the sun in a region called the photosphere. The photosphere has a temperature of 5,800 degrees Kelvin. Sunspots have temperatures of about 3,800 degrees K. T hey look dark only in comparison with the brighter and hotter regions of the photosphere around them.

Solar Flares A solar flare is a tremendous explosion on the Sun that happens when energy stored in 'twisted' magnetic fields (usually above sunspots) is suddenly released. In a a few minutes they heat material to many millions of degrees and produce a burst of radiation across the electromagnetic spectrum, including from radio waves to x- rays and gamma rays.

Prominences A large, bright, gaseous feature extending outward from the Sun's surface, often in a loop shape. Prominences are anchored to the Sun's surface in the photosphere, and extend outwards into the Sun's corona.

Layers of the Sun The energy produced through fusion in the Sun’s core, powers the Sun and produces all of the heat and light that we receive here on Earth. The Sun can be divided into six layers. Core Radiative zone Convective zone Photosphere (visible surface) Chromosphere Corona (outermost layer)

Core The Inner Core The main engine of this star. Gravity and heat provide the necessary energy to drive the nuclear fusion processes that power the sun Almost all the heat from the sun is created in the inner core

Radiative zone Just outside the Inner Core of the sun at a distance approximately 0.25 to 0.7 solar radii lies the Radiative Zone. This zone radiates energy through the process of photon emission and capture by the hydrogen and helium ions.

Convection zone Moving from a distance of approximately 200,000 Km (125,000 mi) lies the Convective Zone of the Sun. This zone is not dense enough to use radiative transfer of energy, instead, it uses thermal convection zones, in other words, it boils. Energy is carried through thermal columns to the surface of the sun and creates areas that we see as solar granulation and super granulation.

Photosphere On the surface of the sun, we reach the Photosphere. Region of the sun is opaque (or optically dark) to light. Where the light from the sun is emitted. The light is emitted through the interaction of electrons with Hydrogen atoms.

Chromosphere Second of the three main layers in the Sun’s atmosphere 3,000 to 5,000 kilometers deep It’s rosy red color is only apparent during eclipses The Chromosphere sits just above the photosphere and below the solar transition region The layer of the chromosphere atop the photosphere is homogeneous.

Corona An aura of plasma that surrounds the sun and other stars. The Sun's corona extends millions of kilometers into space and is most easily seen during a total solar eclipse, but it is also observable with a coronagraph.

Coronal Mass Ejections The ejected material is a plasma consisting primarily of electrons and protons. Relatively slow Associated with enormous changes and disturbances in the coronal magnetic field They are usually observed with a white- light coronagraph

Nuclear Reactions Inside the Sun’s core there are atoms of hydrogen joining together ("fusing") to make atoms of helium, releasing huge amounts of energy in the process. The sun created incredible amounts of heat It’s nuclear fusion produces solar energy that streams out across 150 million kilometers (93 million miles) of space sustaining pretty much all the life we see on Earth