A ________________ is a huge mass made of very hot gases (____________________ and ____________________) which produces energy through ________ ___________ process, and then emits such energy in the form of radiation Star HydrogenHelium Nuclear Fusion What is the closest star to Earth? SUN Proxima Centauri is the next closest at 4.2 light years away

What is the sun made of? 73% ___________________ 25%____________________ Hydrogen Helium Is it a big star? No, it is an average (medium) size star

CORE RADIATIVE CONVECTIVE PHOTOSPHERE CHROMOSPHERE CORONA

The Sun’s Interior Core: __________ has a tremendously high temperature and pressure. The temperature is roughly 15 million °C. Here is where nuclear fusion occurs, turning four hydrogen nuclei into a single helium nucleus plus a LOT of energy.

The Sun’s Interior Radiative Zone: _____________________emits radiation. that spreads outwards. The temperature ranges from 15 million °C to one million °C. It may take photons of radiation millions of years to pass through the radiative zone, as they gradually make their way out outwards.

The Sun’s Interior Convective Zone: outwards. ____________________ the photons continue to travel outwards via convection (towards lower temperature and pressure). The temperature ranges from one million °C to 6,000 °C.

Outer Layers of the Sun Photosphere Chromosphere Corona

Photosphere ________________: Surface of the sun (lower atmosphere) Consists of a layer of glowing gas (300 miles thick) which radiates most of the _____________ we see. The temperature is about 5,500 °C It has a thick grainy texture consisting of numerous, relatively small, bright markings called ____________. light granules ____________ are cool, dark spots on the surface. They are much bigger than the Earth. They occur in a 11-year cycles. Sunspots

________________ is the layer above the photosphere. It is a very thin layer that appears reddish in color Temperatures ranging from 6,000 °C (at lower altitudes) to 50,000 °C (at higher altitudes). This layer is a few thousand miles thick. ________________ is the layer above the chromosphere. The corona extends for millions of miles Temperatures are tremendous, reaching one million °C. Chromosphere Corona

Solar flare _______________ is a magnetic storm which includes a sudden, rapid, and intense variation in brightness. Radiation is emitted across almost the entire electromagnetic spectrum. Solar Prominence_______________________ is an arc of gas that erupts from the surface of the Sun. They form magnetic loops that hold relatively cool, dense gas suspended above the surface of the Sun.

Solar Wind The top of the corona is constantly flowing into space, where it becomes _________ ____________. Solar wind

How do we know what elements are in the sun and other stars? By using spectroscopy Spectroscopy ______________: the study of the spectrum of luminous beams and began back in the 19 th century. Separates various components of beams of light, different wavelength Figures out the chemical composition of stars

Spectrum shows absorption lines (absorbs that wavelength of light) These lines show what elements are in the stars (spectral types).