Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 Welcome! Sun and Seasons Revised for Harris County Dept of Education Workshop, Feb. 3., 2009, by Christine Shupla, shupla@lpi.usra.edu Photo from http://sohowww.nascom.nasa.gov/bestofsoho/bestofsoho.html 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. Lunar and Planetary Institute

What are we going to cover Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 What are we going to cover Properties of the Sun Influence on Earth: Gravity Light Solar wind Life cycle of the Sun Seasons Photo from http://sohowww.nascom.nasa.gov/bestofsoho/ Photo from http://sohowww.nascom.nasa.gov/bestofsoho/bestofsoho.html Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 The Sun Is a star Made of gases Is our primary source of energy 70% hydrogen and 28% helium Light (radiation) The Nine Planets website has all of this excellent information: http://seds.lpl.arizona.edu/nineplanets/nineplanets/sol.html The Sun contains 99.8% of all of the mass in our Solar System. It is a yellow, medium-temperature star– 9,981°F (5527°C) on the outside and 28 million°F (15 million°C) in the center. Image at http://science.nasa.gov/headlines/y2007/images/chromosphere/LimbFlareJan12_strip2.jpg Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 How Big is the Sun? Activity: Let’s measure the Sun Our Sun is 865 thousand miles (1,390,000 km) wide. Even a medium-sized sunspot is as big at the Earth! Photo from http://sohowww.nascom.nasa.gov/bestofsoho/ Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 How Big is the Sun? About 110 times wider than Earth Or 1.3 million times bigger than Earth Our Sun is 865 thousand miles (1,390,000 km) wide. Even a medium-sized sunspot is as big at the Earth! Photo from http://sohowww.nascom.nasa.gov/bestofsoho/ Photo from http://sohowww.nascom.nasa.gov/bestofsoho/bestofsoho.html Lunar and Planetary Institute

How does our Sun compare to other Stars? Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 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 a dwarf—medium mass Our Sun is a medium-bright dwarf Our Sun is in-between--yellow Supergiants can be hundreds to thousands of times bigger than our Sun, and possibly up to 100 times more massive than our Sun. The smallest stars are about 1/100 of the Sun’s mass. Temperature ranges for the outside of a star (spectral classification): O (blue), B (blue-white), A (white), F (white-yellow), G (yellow), K (orange), M (red) Very large stars can be very hot on the outside (O class) or cool on the outside (all the way down to M class)—all large stars are extremely hot in their cores. All small active stars (excludes remaining cores of old stars) are cooler on the outside and in their cores, compared to the most massive stars. Lunar and Planetary Institute

So is our Sun an average star? Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 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 For more details and a graph, go to Nick Strobel’s Astronomy Notes: http://www.astronomynotes.com/starprop/s14.htm Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 Sun’s Magnetic Field Winds up due to differential rotation 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/dynamosm.mpg Animation of how the Sun's magnetic field winds up and loops out. Movie at http://sohowww.nascom.nasa.gov/bestofsoho/Movies/dynamo/dynamosm.mpg Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 Inside the Sun Core Radiative Zone Convection zone Image at http://solarscience.msfc.nasa.gov/interior.shtml Core .25 of the Sun’s radius H fusing to form He Radiative Zone .25 to .85 of Sun’s radius Energy radiated from one particle to the next Interface Layer Change in fluid flow generates Magnetic field Convection zone .85 to 1.0 of Sun’s radius Gases rising in circulation cells Radiation is formed in the core from nuclear fusion—hydrogen atoms fusing to form helium The radiation escapes from the core and bounces around in the radiative layer, with atoms absorbing the radiation then re-releasing it in random directions. The radiation moves more quickly through the convection layer, as the atoms are being circulated up to the surface in circulation cells. Finally, when the radiation reaches the bottom of the atmosphere (the photosphere) it is emitted into space, primarily as visible light. The radiation takes thousands to millions of years to travel from the core to the Sun’s atmosphere. It only takes 8 minutes to reach us on Earth. Image at http://solarscience.msfc.nasa.gov/interior.shtml Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 The Sun’s Atmosphere Photosphere Chromosphere Corona Photosphere image and information: http://science.msfc.nasa.gov/ssl/pad/solar/surface.htm Chromosphere image and information: http://science.msfc.nasa.gov/ssl/pad/solar/chromos.htm Corona information: http://science.msfc.nasa.gov/ssl/pad/solar/corona.htm Corona image from http://sohowww.nascom.nasa.gov/gallery/top10/top10_results.html Go to http://son.nasa.gov/tass/content/structure.htm for additional information 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 Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 Energy from the Sun Nuclear chain reaction (hydrogen forming helium) Releases radiation (gamma rays) The gamma ray loses energy as it bounces around inside the Sun It is finally released at the photosphere, primarily as visible light Information and images at http://solarscience.msfc.nasa.gov/interior.shtml . Image at http://solarscience.msfc.nasa.gov/interior.shtml Lunar and Planetary Institute

Features in the Photosphere Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 Features in the Photosphere Sunspots Dark and small (but brighter than Full Moon and big as Earth) Cool-- temperatures only 6,200 F (Sun’s surface is 10,000 F) 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 Information at http://solarscience.msfc.nasa.gov/feature1.shtml Image at http://sohowww.nascom.nasa.gov/gallery/top10/top10_results.html Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 More on Sunspots Our Sun has an activity cycle of 11 years Sunspots appear at specific latitudes on Sun Bands of latitude move towards equator during cycle Basic information and image at http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question17.html Sunspot cycle and detailed data for activities at http://solarscience.msfc.nasa.gov/SunspotCycle.shtml Images at http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question17.html and http://solarscience.msfc.nasa.gov/SunspotCycle.shtml Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 Solar Events Flares (Explosions of energy on the surface of the Sun) Prominences 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 Information on flares at http://solarscience.msfc.nasa.gov/flares.shtml Movie: Six months with EIT 171 (Aug. 12, 2003 - Feb. 9, 2004) http://sohowww.nascom.nasa.gov/bestofsoho/Movies/171/EIT171sm.mpg Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 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 and information at http://solarscience.msfc.nasa.gov/the_key.shtml Image at http://solarscience.msfc.nasa.gov/the_key.shtml Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 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 Animation of solar wind impacting the magnetosphere and creating aurora http://sohowww.nascom.nasa.gov/bestofsoho/Movies/animation/Solarwind.mpg Animation of solar wind impacting the magnetosphere and creating aurora http://sohowww.nascom.nasa.gov/bestofsoho/Movies/animation/Solarwind.mpg A booklet is available at http://ds9.ssl.berkeley.edu/auroras/ Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 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 Information at http://son.nasa.gov/tass/content/solarwind.htm This series of images of coronal mass ejections taken with LASCO C3 (May 1-31, 1997) is available at http://sohowww.nascom.nasa.gov/bestofsoho/Movies/C3May97/C3May97sm.mpg The eruption of a huge bubble of hot gas from the Sun Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 CME’s effects on Earth Can damage satellites Very dangerous to astronauts Power problems Animation of a CME leaving the Sun, slamming into our magnetosphere. http://sohowww.nascom.nasa.gov/bestofsoho/Movies/recon/reconsm.mpg Animation of a CME leaving the Sun, slamming into our magnetosphere. http://sohowww.nascom.nasa.gov/bestofsoho/Movies/recon/reconsm.mpg Lunar and Planetary Institute

Influences on Earth Gravity Light (Radiation) Solar Wind (already discussed)

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 Gravity Orbits The Sun’s powerful gravity keeps the planets in orbit From http://www.enchantedlearning.com/subjects/astronomy/moon/Tides.shtml Lunar and Planetary Institute

Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 Radiation Our Sun (and all active stars) emits radiation Radio, infrared, visible, ultraviolet, x-ray and even some gamma rays Most of the sunlight is yellow-green visible light or close to it Some information at http://antwrp.gsfc.nasa.gov/apod/ap000815.html Image and info at http://csep10.phys.utk.edu/astr162/lect/sun/spectrum.html or http://imagine.gsfc.nasa.gov/docs/teachers/gammaraybursts/imagine/page18.html 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 . Lunar and Planetary Institute

Sun’s Radiation at Earth Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 Sun’s Radiation at Earth The Earth’s atmosphere filters out some frequencies Ozone layer protects us from some ultra-violet, and most x-rays and gamma rays Water and oxygen absorb some radio waves Water vapor, carbon dioxide, and ozone absorbs some infrared http://coolcosmos.ipac.caltech.edu/cosmic_classroom/ir_tutorial/what_is_ir.html Electromagnetic spectrum http://coolcosmos.ipac.caltech.edu/cosmic_classroom/ir_tutorial/what_is_ir.html . Lunar and Planetary Institute

Sunlight is absorbed by Earth The Sun does NOT send “heat rays” into space. Some of its light is infrared, but that is not the same thing as heat. The Sun’s light is absorbed by Earth (clouds, plants, oceans, rock…) By absorbing the light, we are transforming it into heat energy

Sun as a Source of Energy Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 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 Left image caption Every day the Moderate-resolution Imaging Spectroradiometer (MODIS) measures sea surface temperature over the entire globe with high accuracy. This false-color image shows a one-month composite for May 2001. Red and yellow indicates warmer temperatures, green is an intermediate value, while blues and then purples are progressively colder values. Information about the water cycle at http://science.hq.nasa.gov/oceans/system/water.html 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 Lunar and Planetary Institute

Sun as a Source of Energy Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 Sun as a Source of Energy Plants need light for photosynthesis 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 Lunar and Planetary Institute

In a few Billion years… Red Giant Image at http://hubblesite.org/newscenter/archive/releases/1997/26/image/a/

Our Sun’s Habitable Zone Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 Our Sun’s Habitable Zone Billions of years ago, things may have been different The Sun was cooler (by up to 30%!) Earth’s atmosphere was different (thicker, carbon dioxide) Conditions will be different in the future By many accounts, increases in the Sun’s temperature will make Earth uninhabitable in 1 billion years or less These changes will also affect other planets… Mars? Animation at http://www.nasa.gov/97994main_BHabitableZone.MPG Information on Venus’ history at http://www.nineplanets.org/venus.html Information on Mars’ history at http://www.nineplanets.org/mars.html Details and animations at http://www.nasa.gov/centers/goddard/news/topstory/2005/0801frozenworlds.html A sun-like star grows into its red giant phase, increasing in size and luminosity. Energy in the form of heat can now reach a once-frozen and dead moon. The icy surface quickly melts into liquid water, filling in old craters with warmer seas. The stage is now set for the possible formation of new life. Details on solar constant at http://www-das.uwyo.edu/~geerts/cwx/notes/chap02/solar_constant.html Lunar and Planetary Institute

By 5 billion years… White Dwarf Notes for HCDE Workshop on Sun and Seasons Feb. 4, 2009 By 5 billion years… White Dwarf NOVEMBER 5, 1998: NGC 3132 is a striking example of a planetary nebula. This expanding cloud of gas surrounding a dying star is known to amateur astronomers in the Southern Hemisphere as the "Eight-Burst" or the "Southern Ring" Nebula. The name "planetary nebula" refers only to the round shape that many of these objects show when examined through a small telescope. In reality, these nebulae have little or nothing to do with planets, but are instead huge shells of gas ejected by stars as they near the ends of their lifetimes. NGC 3132 is nearly half a light year in diameter, and at a distance of about 2,000 light-years is one of the nearest known planetary nebulae. The gases are expanding away from the central star at a speed of 9 miles per second. Image at http://hubblesite.org/newscenter/archive/releases/nebula/planetary/1998/39/results/50/ Lunar and Planetary Institute