Fusion vs Fission Fission Fusion Division of an atom’s nucleus Chain reaction Uses Uranium 235 to generate energy Create nuclear waste that lasts 100,000+ years Fusion Combination of the nucleus of Hydrogen atoms Found in stars Produces no nuclear waste Lots of energy!!!!

Fusion

Fission

26.1 THE SUN What is the Sun? What causes the Sun to shine? How long does it take energy from the Sun to get to Earth? Why is it said that when we see the stars we see history?

Sun-General Info Composed of H (70%) & He (28%) Most atoms are stripped of their electrons Forms a plasma of ionized gas Approx. 15 million K at core & 5800 K at surface (Pressure 340 billion x Earth's pressure

Energy from the Sun Nuclear fusion converts mass into energy in Sun’s core (temp. 27,000,000 F) Heat & pressure (from gravity) so intense causes nuclei to fuse (Sun’s core) H (two) nuclei's fused  He = enormous release of heat & energy that blast outward as heat & light (Sun’s core)

Force & Balance Energy from nuclear fusion at sun’s core – ions move faster Outward push of thermal (heat) pressure Gravity pulls gas inward at same time Sun remains stable due to balance in forces

Sun’s Interior : Core & Radiation Zone Fusion energy moves outward from core two ways :radiation/convection Radiation zone: regions with highly compressed gas, transferred by the absorption & re-radiation of electromagnetic waves So dense may take energy from core 100,00 years to move to surface of Sun & escape

Convection Zone From radiation zone energy moves into convection zone Outer layer of Sun’s interior Energy transferred outward by convection currents Hot gases rise & cooler gases sink become hot again, etc.

Sun’s Atmosphere Three layers Photosphere Chromosphere Corona

Photosphere Innermost layer of sun’s atmosphere Visible surface 500 km thick 5800 K Sun’s surface –not solid Bubbly – granular appearance

Chromosphere Outside the photosphere 10,000K H emits reddish light Visible mostly during total solar eclipse

Corona Outmost layer of Sun’s atmosphere Very thin gases 1,000,000 K though w/ very low density total amt of thermal energy small compared to total Sun Extends millions of km above chromosphere Light energy = photons No mass, 186,000 m/s Also visible during solar eclipses 6th period stopped here

Solar Wind Stream of electrically charged particles Flow outward from sun through solar system Hits earth’s magnetic field where particles are deflected Produce auroras 3rd period got here

Auroras (Northern Lights)

Atmospheric Features Sunspots Areas of darker, cooler gases (only a few million degrees K) Give off less energy Some larger than Earth Found in groups w/ intense magnetic fields Last days to months 11 year cycles Show motions of Sun’s surface

Atmospheric Features pt. 2 Prominences Huge loops of gas - erupt from sunspots Extend upward from photosphere into chromosphere/corona (100,000 km above sun surface) Travel along magnetic field lines that connect sunspots

Atmospheric features pt. 3 Solar flares occur when surface of sun erupts producing x-rays & charges particles at speeds of 1000 km/s or more Occur near sunspots Heat parts of corona to 20 million K Increases solar winds Disturbs communications, radio, cell phone, TV etc.

Sun’s Magnetic Field Produced on the Sun by the flow of electrically charged ions & electrons Magnetic forces change the direction & motion of moving charged particles like electrons