The Sun

The Sun

• The largest object in our solar system

• You can line-up about 109 Earths across the Sun

• Made mostly of Hydrogen (70.4%) and Helium (28%)– Remaining 1.6% is made of oxygen, carbon, neon, iron,

nitrogen, silicon, magnesium and sulfur

• Contains more than 99% of all the mass in our solar system– Controls the motions of the planets and other objects

• Combustion – process where a fuel combines with oxygen to produce heat

• Nuclear fusion – combining light atomic nuclei into heavier ones

• Nuclear fission – splitting heavy atomic nuclei into lighter ones

• Radiation – transfer of energy from the Sun to Earth• Convection – transfer of energy by the flow of heated

substances • Conduction – transfer of energy that occurs when

substances touch one another • Electromagnetic Spectrum – made of all types of

radiation including microwaves, visible light, x-rays, gamma rays, radio waves, infrared and ultraviolet

Nuclear Fission vs Nuclear Fusion

• https://www.youtube.com/watch?v=oIe1EDExxyg

• Cookie experiment

• In order for the Sun to stay together and produce heat, there MUST be a balance between gravity and particle motion

• This means that the Sun’s gravity has to be strong enough to keep the most of the stuff inside (hydrogen and helium atoms) from flying off into space, but weak enough that the stuff can move around to make heat

How the Sun Makes Heat1. Nuclear fusion happens in the core (H to He)2. Heat is radiated out from the core to the

convective zone • In this stage convection currents are used to

move heat out to the Sun’s surface3. At the Sun’s surface (called the Photosphere)

heat is radiated out into space• The Photosphere is the part of the sun that we

can see

Electromagnetic Spectrum

Solar Activity• About 22.4 years in length– Magnetic poles N-S– Sun spot number increases to a maximum– Magnetic poles reverse S-N– Sun spot number increases again to a maximum– Magnetic poles return to normal N-S

Solar Features• Solar Wind– Flow of ions from the corona– Interact with Earth’s magnetic field to cause aurora (Northern

and Southern Lights)• Solar Flares– Violent eruptions of particles and radiation from the Sun’s

surface• Prominences– Arc of gas ejected from the chromosphere

• Sun Spots– Dark areas on the surface of the Sun