The Sun : Our Closest StarThe Sun : Our Closest Star

A. The Size of The SunA. The Size of The Sun

1. The sun is a medium size star.1. The sun is a medium size star. 99 % of ALL matter in our solar system is 99 % of ALL matter in our solar system is

in the sun.in the sun. It is about 93 million miles from the Earth It is about 93 million miles from the Earth

or 150 million kilometers.or 150 million kilometers. It takes 7.8 min. for light to get to Earth.It takes 7.8 min. for light to get to Earth.

A. The Size of the SunA. The Size of the Sun

The diameter of the sun is 864,000 miles The diameter of the sun is 864,000 miles

( 1. 39 million kilometers) ( 1. 39 million kilometers)

Earth is 12,104 km in diameter ( the sun is Earth is 12,104 km in diameter ( the sun is 116 x BIGGER ! ) ( Earth =7,747 miles)116 x BIGGER ! ) ( Earth =7,747 miles)

B. The Sun has LAYERSB. The Sun has LAYERS

From the inside outFrom the inside out: ( see p 679 ): ( see p 679 ) CoreCore Radiation ZoneRadiation Zone Convection ZoneConvection Zone PhotospherePhotosphere ChromosphereChromosphere CoronaCorona

B. Continued…LayersB. Continued…Layers

1. Light comes from the 1. Light comes from the PhotospherePhotosphere 2. The 2. The Corona Corona isis thousands of miles thick.thousands of miles thick.

It’s temperature = 2,000,000 degrees CIt’s temperature = 2,000,000 degrees C

The temperature of the The temperature of the corecore is is 15,000,000 Degrees C.15,000,000 Degrees C.

B. The Sun has Layers:B. The Sun has Layers:

C. Surface Features of The SunC. Surface Features of The Sun

Solar Flares Solar Flares ProminencesProminences Sun SpotsSun Spots

C. Surface Features of the SunC. Surface Features of the Sun

1. 1. Solar FlaresSolar Flares = violent gas eruptions = violent gas eruptions

a.a. They cause damage to satellites, They cause damage to satellites,

b.b. interfere with radio & T.V., interfere with radio & T.V.,

c.c. and cause Aurora Borealis ( the Northern and cause Aurora Borealis ( the Northern Lights). The Norse myth of the ValkariesLights). The Norse myth of the Valkaries

Is connected to this.Is connected to this.

a.a. Gov. WebGov. Web

C. Surface Features of the SunC. Surface Features of the Sun

2. 2. ProminencesProminences = huge columns of gas = huge columns of gas that fly out from the sun. that fly out from the sun.

They are thousands of miles long.They are thousands of miles long. UV & X-rays increase.UV & X-rays increase.

WebWeb

Prominences are HUGEProminences are HUGE

C. Surface Features…C. Surface Features…

Sun SpotsSun Spots = Dark areas that are cooler = Dark areas that are cooler parts on the sun’s surface.parts on the sun’s surface.

a.a. This shows that the sun ROTATES.This shows that the sun ROTATES.

b.b. Spots are not permanent. They last from Spots are not permanent. They last from days to months.days to months.

c.c. The “sun spot maxima” occurs every 11 The “sun spot maxima” occurs every 11 years.years.

D. Nuclear Fusion Occurs in the D. Nuclear Fusion Occurs in the Sun’s CoreSun’s Core

Hydrogen atoms join to become Helium Hydrogen atoms join to become Helium atoms. atoms.

This is a nuclear reaction ( not a chemical This is a nuclear reaction ( not a chemical reaction. Chemical reactions involve reaction. Chemical reactions involve electrons.)electrons.)

VideoVideo

E. NASA’s Tools For Studying E. NASA’s Tools For Studying the Sunthe Sun

Solar ProbesSolar Probes SOHO SOHO Space Observatory Space Observatory (1.5 million km (1.5 million km

above Earth)above Earth)

The primary scientific aims of the Solar and The primary scientific aims of the Solar and Heliospheric Observatory mission (SOHO)Heliospheric Observatory mission (SOHO)