Chapter 20.2 The Sun: Our Very Own Star

Structure of the Sun The sun is basically a large ball of gas –M–Made mostly of Hydrogen and Helium –H–Held together by Gravity May appear to have a solid surface –N–No –V–Visible surface starts where gases are so thick, you can’t see through it.

Layers of the Sun

Structure of the Sun

Energy Production Scientists believed: Sun burned fuel to generate energy –(–(would only last for 10,000 years) Gravity was causing sun to shrink and gravity would release energy to heat sun –(–(would only last for 45 million years) Sun has been shining for 4.6 billion years

Nuclear Fusion Albert Einstein showed that matter and energy are interchangeable- E=mc² –(E-energy, m-mass, c- speed of light) Since c is such a large number, tiny amounts of matter can produce a huge amount of energy. Nuclear fusion= process by which two or more low-mass nuclei fuse to form one larger nucleus 4 H → 1 He = Energy (Sun’s energy)

Nuclear Fusion

Fusion in the Sun Core –W–Where energy is produced (nuclear fusion) Radiative Zone –V–Very dense, energy passes through here Convective Zone –H–Hot gases circulate here when energy passes Photosphere –V–Visible portion where energy leaves sun as light –T–Takes 8.3 minutes to reach Earth

Solar Activity Convection of hot gases + sun’s rotation= Magnetic Fields Solar wind –C–Constant flow of magnetic fields from sun –C–Can cause interference with the Earth’s magnetic field disrupting TV signals and damaging satellites

Solar Wind

Sunspots The sun’s magnetic fields tend to slow down activity in the Convective zone. When activity slows down, some areas of the Photosphere become cooler. These cooler areas show up as Sunspots. These cooler, darker spots cycle every 11 years and have been linked to low temperatures on Earth’s surface.

Sunspots

Solar Flares Magnetic fields can also cause regions of extremely high temps and brightness that develop on the sun’s surface. When solar flares erupt, it sends huge streams of electrically charged particles into the solar system. Solar flares can interrupt radio communications on the Earth and in orbit.

Solar Features