Welcome!

Sun Characteristics

Created by the Lunar and Planetary Institute

For Educational Use Only

LPI is not responsible for the ways in which this powerpoint may be used or altered.

Photo from http://sohowww.nascom.nasa.gov/bestofsoho/bestofsoho.html

What are we going to cover

• Properties of the Sun

• Influence on Earth:

– Gravity

– Light

– Solar wind

• Life cycle of the Sun

Photo from http://sohowww.nascom.nasa.gov/bestofsoho/bestofsoho.html

The Sun

• Is a star

• Made of hot gases

• Is our primary source of energy

70% hydrogen and 28% helium

Light (radiation) and Thermal

Image at

http://science.nasa.gov/headlines/y2007/images/chromosphere/LimbFlareJan12_strip2.jpg

How Big is the Sun?

About 110 times

wider than Earth

Or

1.3 million times

bigger than Earth

(1,300,000 Earths)

Photo from http://sohowww.nascom.nasa.gov/bestofsoho/bestofsoho.html

How does our Sun compare to other Stars?

• Active stars range in size from supergiants to dwarfs

• Stars range from very bright (supergiants) to very dim (dwarfs)

• Stars range from very hot blue on the outside (O class) to cool red on the outside (M class)

Our Sun is in-between--yellow

Our Sun is a dwarf—medium

mass

Our Sun is a medium-bright

dwarf

So is our Sun an average star?

• No—most stars are smaller and cooler than our Sun BUT

• Most of the bright stars we see are bigger and hotter

• Our sun is a medium-sized dwarf star.

• It is about 5 billion years old and should last about another 5 billion years.

Rotation

The sun’s rotation takes about 27 days.

High cadence solar rotation, EIT 195Š(Dec. 10-24, 1999) Movie at

http://sohowww.nascom.nasa.gov/bestofsoho/Movies/EITdec99/EITdec99sm.mpg

Inside the Sun

• Core

• Radiation Zone

• Convection zone

Image at http://solarscience.msfc.nasa.gov/interior.shtml

Outside the Sun

• Photosphere – The part of the sun that we see – Has sunspots

• Chromosphere

• Corona

Photosphere image: http://science.msfc.nasa.gov/ssl/pad/solar/surface.htm

Chromosphere image: http://science.msfc.nasa.gov/ssl/pad/solar/chromos.htm

Corona image: http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=191

Solar Events

• Sunspots

– Dark, small (Earth size), cool spots (temperatures only 6,200 F when Sun’s surface is 10,000 F)

• Solar Flares

– Explosions of energy on the surface of the Sun

• Solar Prominences

– Loops of hot gases

• Coronal Mass Ejections (CME)

– Massive clouds of plasma ejected from the Sun

– Can damage satellites, is dangerous to astronauts, and can cause power problems

This series of images of coronal mass ejections taken with LASCO C3 (May 1-31, 1997) at

http://sohowww.nascom.nasa.gov/bestofsoho/Movies/C3May97/C3May97sm.mpg

Solar Wind

• Blows charged particles and magnetic fields away from the Sun

• Charged particles captured by Earth’s magnetic field

• Create Auroras or Northern and Southern Lights

Image at http://solarscience.msfc.nasa.gov/the_key.shtml

Auroras

• Electrons from solar wind are captured by the Earth’s magnetic field

• Interact with atoms in our atmosphere: oxygen and nitrogen make red and green; nitrogen can also make violet

• Northern lights are Aurora Borealis, while southern are Aurora Australis

Video of how the sun creates auroras

http://link.brightcove.com/services/player/bcpid1091263959

001?bckey=AQ~~,AAAABvb_NGE~,DMkZt2E6wO0aqwg3

BkGVZipVhkS_MPQH&bclid=0&bctid=1162781056001

Total Solar Eclipse

• The Sun is blocked by the moon

• You can see the red ring of the chromosphere and the white crown of the corona

• One every 18 months

• ~400 years in same location

The Sun’s Influences on Earth

• Gravity

– Keeps the planets in their orbits

• Light (Radiation) and Thermal energy

– Makes life possible

– Plants need light for photosynthesis

– Creates wind, water currents, water cycle, and weather

• Solar Wind (already discussed)

Sun as a Source of Energy

• Light from the Sun is absorbed by the Earth, unevenly to:

– drive wind bands – which drive surface currents

– drive deep ocean currents

– drive water cycle

– drive weather

NASA image at http://visibleearth.nasa.gov/view_rec.php?id=107 Credit: NASA GSFC Water and Energy Cycle

http://www.nasa.gov/centers/jpl/news/grace-20061212.html

Our Sun is an Average, Medium Star

Image at http://www.gsfc.nasa.gov/topstory/20011210insidesun.html

Left White Circle

Label the following:

•Convection Zone

•Radiation Zone

•Core

Middle Yellow Circle

Write

“PHOTOSPHERE”

Draw and label the

following:

•Solar Flare

•Solar Prominence

•2-3 Sunspots

On Your Journal Page

•Add a layer and write “CHROMOSPHERE”

•Add another layer that looks like a crown and write

“CORONA”

Sun Facts

•The Sun is made of flaming hot hydrogen and helium

gases.

•The Sun’s gravity holds all of the planets in their orbits.

•The Sun is spherical in shape and is located in the center of

our solar system.

•The sun is a medium-sized dwarf star.

•The Sun’s light and thermal energy makes life on Earth

possible and is also responsible for producing wind, water

currents, weather, and the water cycle.

Solar Links

• NASA Solar Physics

– http://solarscience.msfc.nasa.gov/whysolar.shtml

• Solar & Heliospheric Observatory (SOHO)

– http://sohowww.nascom.nasa.gov/home.html

• Helioviewer

– http://www.helioviewer.org/