chapter 20.2 the sun: our very own star. structure of the sun the sun is basically a large ball of...
TRANSCRIPT
Structure of the Sun
• The sun is basically a large ball of gas– Made mostly of Hydrogen and Helium – Held together by Gravity
• May appear to have a solid surface– No– Visible surface starts where gases are so
thick, you can’t see through it.
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)
Fusion in the Sun• Core
– Where energy is produced (nuclear fusion)
• Radiative Zone– Very dense, energy passes through here
• Convective Zone– Hot gases circulate here when energy passes
• Photosphere– Visible portion where energy leaves sun as light– Takes 8.3 minutes to reach Earth
Solar Activity
• Convection of hot gases + sun’s rotation=
Magnetic Fields
• Solar wind– Constant flow of magnetic fields from sun– Can cause interference with the Earth’s
magnetic field disrupting TV signals and damaging satellites
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.
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.