Welcome! Sun and Seasons Photo from http://sohowww.nascom.nasa.gov/bestofsoho/bestofsoho.html 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. What are we going to cover вЂў Properties of the Sun вЂў Influence on Earth: вЂ“ Gravity вЂ“ Light вЂ“ Solar wind вЂў Life cycle of the Sun вЂў Seasons Photo from http://sohowww.nascom.nasa.gov/bestofsoho/bestofsoho.html The Sun вЂў Is a star вЂў Made of gases 70% hydrogen and 28% helium вЂў Is our primary source of energy Light (radiation) Image at http://science.nasa.gov/headlines/y2007/images/chromosphere/LimbFlareJan12_strip2.jpg How Big is the Sun? Activity: LetвЂ™s measure the Sun How Big is the Sun? About 110 times wider than Earth Or 1.3 million times bigger than Earth Photo from http://sohowww.nascom.nasa.gov/bestofsoho/bestofsoho.html How does our Sun compare to other Stars? вЂў Active stars range in size from supergiants to dwarfs вЂў Stars range from very bright (supergiants) to very dim (dwarfs) вЂў Stars range from very hot blue on the outside (O class) to cool red on the outside (M class) Our Sun is a dwarfвЂ”medium mass Our Sun is a medium-bright dwarf Our Sun is in-between--yellow So is our Sun an average star? вЂў NoвЂ”most stars are smaller and cooler than our Sun BUT вЂў Most of the bright stars we see are bigger and hotter Rotation High cadence solar rotation, EIT 195Е (Dec. 10-24, 1999) Movie at http://sohowww.nascom.nasa.gov/bestofsoho/Movies/EITdec99/EITdec99sm.mpg At the equator, the Sun rotates once every 25.4 days Near its poles, the Sun rotates once every 36 days Known as вЂњdifferential rotationвЂќ SunвЂ™s Magnetic Field вЂў Winds up due to differential rotation вЂў Eventually forms loops and becomes tangled Animation of how the Sun's magnetic field winds up and loops out. Movie at http://sohowww.nascom.nasa.gov/bestofsoho/Movies/dynamo/dynamos m.mpg Inside the Sun вЂў Core вЂў Radiative Zone вЂў Convection zone Image at http://solarscience.msfc.nasa.gov/interior.shtml The SunвЂ™s Atmosphere вЂў Photosphere вЂў Chromosphere вЂў 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 Energy from the Sun вЂў Nuclear chain reaction (hydrogen forming helium) вЂў Releases radiation (gamma rays) вЂў The gamma ray loses energy as it bounces around inside the Sun вЂў It is finally released at the photosphere, primarily as visible light Image at http://solarscience.msfc.nasa.gov/interior.shtml Features in the Photosphere вЂў Sunspots вЂ“ Dark and small (but brighter than Full Moon and big as Earth) вЂ“ Cool-- temperatures only 6,200 F (SunвЂ™s surface is 10,000 F) вЂ“ Associated with magnetic fields: one set of spots is positive, other is negative Image at http://sohowww.nascom.nasa.gov/gallery/top10/top10_results.html More on Sunspots вЂў Our Sun has an activity cycle of 11 years вЂў Sunspots appear at specific latitudes on Sun вЂ“ Bands of latitude move towards equator during cycle Images at http://starchild.gsfc.nasa.gov/docs/StarChild/questions/q uestion17.html and http://solarscience.msfc.nasa.gov/SunspotCycle.shtml Solar Events вЂў Flares (Explosions of energy on the surface of the Sun) вЂў Prominences вЂў Coronal Mass Ejections (massive clouds of plasma ejected from the Sun) Movie: Six months with EIT 171 (Aug. 12, 2003 - Feb. 9, 2004) http://sohowww.nascom.nasa.gov/bestofsoho/Movies/171 /EIT171sm.mpg Solar Wind вЂў Blows charged particles and magnetic fields away from the Sun вЂў Charged particles captured by EarthвЂ™s magnetic field вЂў Create Auroras or Northern and Southern Lights Image at http://solarscience.msfc.nasa.gov/the_key.shtml Auroras вЂў Electrons from solar wind are captured by the EarthвЂ™s magnetic field вЂў Interact with atoms in our atmosphere: oxygen and nitrogen make red and green; nitrogen can also make violet вЂў Northern lights are Aurora Borealis, while southern are Aurora Australis Animation of solar wind impacting the magnetosphere and creating aurora http://sohowww.nascom.nasa.gov/bestofsoho/Movies/ani mation/Solarwind.mpg Coronal Mass Ejection 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 The eruption of a huge bubble of hot gas from the Sun CMEвЂ™s effects on Earth вЂў Can damage satellites вЂў Very dangerous to astronauts вЂў Power problems Animation of a CME leaving the Sun, slamming into our magnetosphere. http://sohowww.nascom.nasa.gov/bestofsoh o/Movies/recon/reconsm.mpg Activities вЂў LetвЂ™s go observe the Sun вЂў Sunspot graphing Influences on Earth вЂў Gravity вЂў Light (Radiation) вЂў Solar Wind (already discussed) Gravity вЂў Orbits вЂ“ The SunвЂ™s powerful gravity keeps the planets in orbit Radiation вЂў Our Sun (and all active stars) emits radiation вЂ“ Radio, infrared, visible, ultraviolet, x-ray and even some gamma rays вЂ“ Most of the sunlight is yellow-green visible light or close to it The Sun at X-ray wavelengths Image and info at http://imagine.gsfc.nasa.gov/docs/teachers/gammaraybursts/imagine/page18.html and http://starchild.gsfc.nasa.gov/docs/StarChild/solar_system_level2/sun.html Activities on Sunlight вЂў UV Man (or woman, or dog, bug, etc.) вЂў Observations of infrared light using filters and cell phones SunвЂ™s Radiation at Earth вЂў The EarthвЂ™s atmosphere filters out some frequencies вЂ“ Ozone layer protects us from some ultra-violet, and most xrays and gamma rays вЂ“ Water and oxygen absorb some radio waves вЂ“ Water vapor, carbon dioxide, and ozone absorbs some infrared Electromagnetic spectrum http://coolcosmos.ipac.caltech.edu/cosmic_classroom/ir_tutorial/what_is_ir.html . Sunlight is absorbed by Earth LetвЂ™s test what happens to the light. Activity Time!! Sunlight is absorbed by Earth вЂў The Sun does NOT send вЂњheat raysвЂќ into space. Some of its light is infrared, but that is not the same thing as heat. вЂў The SunвЂ™s light is absorbed by Earth (clouds, plants, oceans, rockвЂ¦) вЂў By absorbing the light, we are transforming it into heat energy Sun as a Source of Energy вЂў Light from the Sun is absorbed by the Earth, unevenly to: вЂ“ drive wind bands вЂ“ which drive surface currents вЂ“ drive deep ocean currents вЂ“ drive water cycle вЂ“ 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 Sun as a Source of Energy вЂў Plants need light for photosynthesis вЂў Without its heat, the only inhabitable areas on Earth would be near volcanic vents Images from http://nasadaacs.eos.nasa.gov/articles/2005/2005_rainforest.html and http://planetquest.jpl.nasa.gov/TPF/tpf_book/gallery/4-2a.html Young stars form in nebulae from Small Magellanic Cloud Image at http://hubblesite.org/newscenter/archive/releases/2007/04/image/a/results/50/ Star-forming region in the Large Magellanic Cloud: http://hubblesite.org/newscenter/archive/releases/2008/31/image/a/results/50/ Orion image at http://hubblesite.org/newscenter/archive/releases/2006/01/image/a/results/50/ Our Sun is a Regular/ Small Star Image at http://www.gsfc.nasa.gov/topstory/20011210insidesun.html In a few Billion yearsвЂ¦ Red Giant Image at http://hubblesite.org/newscenter/archive/releases/1997/26/image/a/ Our SunвЂ™s Habitable Zone Billions of years ago, things may have been different вЂ“ The Sun was cooler (by up to 30%!) вЂ“ EarthвЂ™s atmosphere was different (thicker, carbon dioxide) вЂў Animation at http://www.nasa.gov/97994mai n_BHabitableZone.MPG Conditions will be different in the future вЂ“ By many accounts, increases in the SunвЂ™s temperature will make Earth uninhabitable in 1 billion years or less вЂ“ These changes will also affect other planetsвЂ¦ Mars? By 5 billion yearsвЂ¦ White Dwarf Image at http://hubblesite.org/newscenter/archive/releases/nebula/planetary/1998/39/results/50/ Image at http://hubblesite.org/newscenter/archive/releases/nebula/planetary/2000/28/image/a/format/web_print/results/50/ Image at http://hubblesite.org/newscenter/archive/releases/nebula/planetary/2004/27/image/a/format/large_web/results/50/ Massive Stars are different Image from http://hubblesite.org/newscenter/archive/releases/nebula/emission/1997/33/results/50/ Betelgeuse Image from http://hubblesite.org/newscenter/archive/releases/star/massive%20star/1996/04/image/a/results/50/ SupernovaвЂ”Massive Star Explodes Images at http://hubblesite.org/newscenter/archive/releases/star/supernova/2004/09/results/50/ http://hubblesite.org/newscenter/archive/releases/nebula/supernova-remnant/2005/37/results/50/ http://chandra.harvard.edu/photo/2009/casa/ Done with the Sun вЂў Time for Seasons!