24.3 The Sun

Photosphere• The

region of the sun that radiates energy to space; visible surface of the sun.

Chromosphere• The first layer

of the solar atmosphere found directly above the photosphere.

Corona• The weak layer of the solar atmosphere.

Solar Wind• Streams of protons and electrons ejected at

high speed from the solar corona.

Sunspot• A dark spot on the sun, Which is cooled by

contrast to the surrounding photosphere.

Prominence • A

concentration of gases above the solar surface that appears as a bright arch-like structure.

Solar Flare

• A sudden and tremendous eruption in the solar chromosphere.

Aurora

• A bright display of ever-changing light caused by solar radiation interacting with the upper atmosphere in the regions of the poles.

Nuclear Fusion• The way in which the sun produces energy;

nuclear fusion occurs when less massive nuclei combine into more massive nuclei, releasing tremendous amounts of energy.

Key Concept

• Keeping this in mind, we can divide the sun into four parts: the solar interior; the visible surface, or photosphere; and two atmospheric layers, the chromosphere and corona.

Key Concept

• Sunspots appear dark because of their temperature, which is above 1500 K less than that of the surrounding solar surface.

Key Concept

• Prominences are ionized gases trapped by magnetic fields that extend from regions of intense solar activity.

Key Concept

• During their existence, solar flares release enormous amounts of energy, much of it in the form of ultraviolet, radio, and X-ray radiation.

Key Concept

• During nuclear fusion, energy is released because some matter is actually converted to energy.