Brain Pop The Sun http://www.brainpop.com/science/space/sun/

The Sun The closest star to earth. The reason we have life on earth. Average main sequence star.

Sun’s Mass The Sun is 300,000 times Earth’s mass. The Sun is composed mostly of Hydrogen and some Helium (and ~2% other elements). The Sun is completely gaseous. Diameter = 1,300,000 km The Sun generates energy in its core. Most massive object in the solar system. The sun generates energy in its core that radiates outward through the layers.

Layers of the Sun Atmosphere: Interior The Photosphere (Surface) The Chromosphere The Corona Interior Core Radiation Zone Convection Zone There are 2 parts of the sun: Atmosphere and Interior. The atmosphere consists of the photosphere, chromosphere, and corona. The Interior of the consists of the core, radiative zone and the convective zone.

The Core Fusion of hydrogen to helium Converts mass to energy E=mc2 600 million tons of hydrogen converted to energy every second We are going to describe each of the layer and what goes on in them. Put “Core” in the margin and copy the notes. E= the amount of energy that can be produced by a certain amout of mass. M = mass c = speed of light (constant)

Step 3: proton combines with p/n pair Hydrogen Hydrogen There are basically 5 steps to hydrogen fusion. Step 3: proton combines with p/n pair Step 1: 2 hydrogen atoms fuse Step 2: One proton changes to a neutron. Step 5: this results in formation of Helium Step 4: 2 nuclei fuse

Inner Zones-Energy moves through 2 inner zones Radiative zone Surrounds core 2,500,000 oC Energy is transferred through EM waves Convective Zone Around radiative zone Uses convection to transfer heat to surface Cool gases sink Warm gases rise 1,000,000 oC

Three layers in the uppermost region of solar gases Sun’s Atmosphere Three layers in the uppermost region of solar gases

Photosphere Appears granular due to convection “light sphere” because it gives off visible light. 6000 oC Above the convective zone This is the layer we see. Gives off the visible light

Chromosphere Layer above the photosphere “color sphere” glows red Temp varies greatly 4,000 - 50,000 oC Occasionally form narrow jets of hot gas Hot gases can shoot outward to heights of 16,000 km.

Corona The outermost layer of the Sun’s atmosphere Can only be seen during an eclipse Photosphere too bright Gives off the solar wind Charged particles streaming through the corona Helps keep in charges particles. Some escape through holes in the corona. Solar wind. Suns magnetic field helps protect not only the sun but the whole solar system.

Sun’s Layers - Movie

Homework Do p. 575 1-5 Use complete sentences

Solar Activity p. 576-579

Sunspots “Dark” regions on the Sun. Usually form in pairs We are experiencing a solar minimum “Dark” regions on the Sun. Actually, cooler regions (lower temp. -> less intense). Usually form in pairs Number of spots varies with an 11 year cycle.

Sunspots Position and number of sunspots change over time. The Sun rotates differentially 25.4 days at equator 27.8 days at 45º 11 year cycle of sunspot activity. 2001 – Sunspot maximum (around 100 spots visible). ~5.5 yrs. later – Sunspot minimum (only a few spots visible).

The Cause of Sunspots Different parts of the sun rotate at different speed. As the Sun rotates, the magnetic field is twisted and causes cooler regions. Strong magnetic fields slow down convection = cooler areas show up as sunspots.

Hot Rising Gas Magnetic Field How Sunspots Occur

Prominences Prominences – hot ionized gas trapped in magnetic field lines. Stretch from one sunspot to another.

Solar Flares Sudden outward eruption of electrically charged particles Last only seconds but give off energy = millions of H bombs Usually associated with sunspots May strengthen the solar wind Can cause interference with radio communication on earth. http://www.nasa.gov/mission_pages/sdo/main/index.html

Auroras Northern/Southern Lights http://www.spaceweather.com/ Auroras Northern/Southern Lights Electrically charged particles hit the magnetosphere.

Sun’s Activity-Movie

Answer questions on page 579 p.579 1-5 complete sentences