THE SUN AND ITS CORE

GOALS AND OBJECTIVES BY THE END OF THIS LESSON YOU SHOULD BE ABLE TO SAY “I CAN…” DESCRIBE HOW ENERGY FROM THE SUN IS CREATED. EXPLAIN HOW ATOMS REACT DURING THE PROCESS OF NUCLEAR FUSION IN THE SUN. EXPLAIN WHAT A PHOTON IS, HOW IT IS MADE, AND WHY IT’S IMPORTANT TO OUR EARTH.

HOW BIG IS THE SUN COMPARED TO EARTH? Image copied from Nick Strobel's Astronomy Notes The Sun and planets are shown to the same scale. The small terrestrial planets and tiny Pluto are in the box - the Earth is the blue dot near the center of the box (montage created by Nick Strobel using NASA images).

STARS (LIKE THE SUN) SHINE BECAUSE OF NUCLEAR FUSION REACTIONS IN THEIR CORE. THE MORE LUMINOUS THEY ARE, THE MORE REACTIONS ARE TAKING PLACE IN THEIR CORES. WE’RE GOING TO MAKE SOME REACTIONS OF OUR OWN… NASA/JPL-Caltech

THE POPCORN EXPERIMENT OBSERVE, TAKE NOTES, MAKE CONNECTIONS AS SCIENCE CREATES A TASTY SNACK.

YOUR RESPONSE TO THE POPCORN EXPERIMENT Group discussion: What did you notice about the popcorn machine? What happened as the popcorn popped? What made the popcorn pop? Was it loud or quiet? (is this a form of energy?) Was the weight of the popcorn kernels the same after they popped? Why?

WEIGHT OF POPCORN POPCORN KERNEL WEIGHT BEFORE POPPING: ___________________ POPCORN WEIGHT POST POPPING: ____________________ DIFFERENCE: ________________

WHY DOES THE SUN SHINE? INTRO TO NUCLEAR FUSION

WHAT IS THE SUN MADE OF? Electrons orbiting the nucleus. Protons making up part of the nucleus. Neutrons making up part of the nucleus. D ifferent combinations of protons, neutrons, and electrons make different atoms. ATOMS

ATOMS IN THE SUN… 94% Hydrogen Note: When dealing with NUCLEAR fusion, we focus on the NUCLEUS of the atom. 6% Helium.13% of Sun is made up of oxygen, carbon, iron, and other elements. 1 proton. 1 electron. 2 protons, 2 neutrons, 2 electrons.

WHAT IS NEEDED FOR NUCLEAR FUSION? WHAT DID THE POPCORN NEED TO POP? WHAT DO YOU THINK ATOMS NEED TO FUSE? THE SUN'S CORE IS ABOUT 16 MILLION K AND HAS A DENSITY AROUND 160 TIMES THE DENSITY OF WATER.

NORMALLY LIKE CHARGES REPEL LIKE CHARGES (THINK OF A MAGNET): But at very high temperatures and with very strong gravitational force, the motions of protons are high enough to overcome the forces that keep them apart and the nucleus can fuse.

STEP 1 IN THE FUSION CHAIN REACTION: AS PROTONS FUSE… ONE OF THE PROTONS BECOMES A NEUTRON AND THIS ATOM IS NOW CALLED: DEUTERIUM During the process of fusion, energy is released in the form of two photons (gamma-rays).

PHOTONS Photons (or light particles) are basically envelopes or packets of energy. Energy from the Sun travels to the Earth as photons in a process called radiation.

STEP 2 IN THE CHAIN REACTION THIS FUSION AGAIN RESULTS IN ANOTHER TWO PHOTONS (GAMMA-RAYS) BEING CREATED. Deuterium then fuses with another proton (now its called tritium).

STEP 3 IN CHAIN REACTION TWO TRITIUM ATOMS COLLIDE AND CREATE A HELIUM ATOM. Bye! We’re off to start more chain reactions. tritium helium

BECOME A STAR! REENACT NUCLEAR FUSION

THE KERNELS EVENTUALLY STOP POPPING… HYDROGEN IN THE SUN IS FUELING THE PROCESS OF NUCLEAR FUSION. COMPARED TO SMALLER STARS, IS THE SUN’S RATE OF CONSUMING FUEL MUCH GREATER? WHAT WILL HAPPEN ONCE ALL THE HYDROGEN IN THE SUN IS USED UP?

RECAP OBJECTIVES NUCLEAR FUSION CONVERTED THE NUCLEUS OF FOUR HYDROGEN ATOMS (PROTONS) INTO ONE HELIUM ATOM WITH THE RELEASE OF SEVERAL PHOTONS. ALL THE PHOTONS ARE SCATTERED MANY, MANY TIMES AS THEY LEAVE THE STELLAR CORE. THE PHOTONS CONVERT INTO DIFFERENT TYPES OF LIGHT AND THERMAL ENERGY. PHOTONS ARE THE FUNDAMENTAL PARTICLE OF LIGHT. THEY ARE PACKETS OF ENERGY FROM THE SUN. RADIATION, THE PROCESS OF EMITTING RADIANT ENERGY IN THE FORM OF WAVES OR PARTICLES, CARRIES THAT ENERGY TO OUR EARTH.

Can you explain the atomic reactions that occur in nuclear fusion? Can you explain what a photon is and how it is made? How does this impact life on Earth?