The Sun

Earth Science - Middle School

The Sun Photos courtesy of NASA. Structure of the Sun The Sun is a massive burning ball of gases held together by gravity. It is primarily composed of helium and hydrogen gases. The Sun has three main layers—the core, the radiative zone and the convective zone. The Sun’s atmosphere is made up of the photosphere, chromosphere and corona. Sunspots are cooler, darker areas of gas on the Sun’s surface. Solar Flares Solar flares are enormous areas of extreme temperature on the Sun’s surface, caused by magnetic fields. They typically occur near sunspots. The Photosphere The photosphere is the inner layer of the Sun’s atmosphere. This gaseous layer is thick enough to be visible. When we look at the Sun, we are seeing the photosphere. The Chromosphere Just beyond the photosphere is a thin layer called the chromosphere, which has a reddish color. The chromosphere can be seen during a total solar eclipse when the Moon covers the Sun. The Sun’s Corona The outer atmosphere of the Sun is called the corona. It is composed of gases and extends for millions of kilometers beyond the Sun. The corona can only be seen during a total solar eclipse. © Copyright NewPath Learning. All Rights Reserved. 94-4579 Visit for Online Learning Resources. The Core & Nuclear Fusion The core at the center of the Sun produces the Sun’s heat. This energy is produced by hydrogen nuclear fusion reactions. The Radiative Zone Energy produced in the Sun’s core is carried to the Sun’s surface in the form of light energy called photons. This energy moves from the core into a very dense radiative zone. The Convective Zone The outer layer of the Sun is called the convective zone. Hot gases in this layer rise toward the surface, where they become cooler and denser. The gases then descend back into the Sun. This circulating movement is called convection, and is similar to currents in the Earth’s mantle. core solar eclipse corona chromosphere convection currents photosphere chromosphere flare
Pause and Review Label the structures of the Sun. The Sun Describe each structure. 1. _______________________________________________________________________ 2. _______________________________________________________________________ 3. _______________________________________________________________________ 4. _______________________________________________________________________ 5. _______________________________________________________________________ 6. _______________________________________________________________________ © Copyright NewPath Learning. All Rights Reserved. 94-4579 Visit for Online Learning Resources.