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Sun and Seasons

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Stars range from very bright (supergiants) to very dim (dwarfs) ... Our Sun is a medium-bright dwarf. So is our Sun an average star? ... – PowerPoint PPT presentation

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Title: Sun and Seasons


1
Welcome!
Sun and Seasons
Photo from http//sohowww.nascom.nasa.gov/bestofso
ho/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.
2
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/bestofso
ho/bestofsoho.html
3
The Sun
  • Is a star
  • Made of gases
  • Is our primary source of energy

70 hydrogen and 28 helium
Light (radiation)
Image at http//science.nasa.gov/headlines/y2007/i
mages/chromosphere/LimbFlareJan12_strip2.jpg
4
How Big is the Sun?
Activity Lets measure the Sun
5
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/bestofso
ho/bestofsoho.html
6
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 dwarfmedium mass
Our Sun is a medium-bright dwarf
Our Sun is in-between--yellow
7
So is our Sun an average star?
  • Nomost stars are smaller and cooler than our Sun
    BUT
  • Most of the bright stars we see are bigger and
    hotter

8
Rotation
High cadence solar rotation, EIT 195Š(Dec. 10-24,
1999) Movie at http//sohowww.nascom.nasa.gov/best
ofsoho/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 differential rotation
9
Suns 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
10
Inside the Sun
  • Core
  • Radiative Zone
  • Convection zone

Image at http//solarscience.msfc.nasa.gov/interio
r.shtml
11
The Suns Atmosphere
  • Photosphere
  • Chromosphere
  • Corona

Photosphere image http//science.msfc.nasa.gov/s
sl/pad/solar/surface.htm Chromosphere image
http//science.msfc.nasa.gov/ssl/pad/solar/chromos
.htm Corona image http//solarsystem.nasa.gov/mu
ltimedia/display.cfm?IM_ID191
12
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

Image at http//solarscience.msfc.nasa.gov/interio
r.shtml
13
Features in the Photosphere
  • Sunspots
  • Dark and small (but brighter than Full Moon
    and big as Earth)
  • Cool-- temperatures only 6,200 F (Suns 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/to
p10/top10_results.html
14
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

Images at http//starchild.gsfc.nasa.gov/docs/Star
Child/questions/question17.html and
http//solarscience.msfc.nasa.gov/SunspotCycle.sht
ml
15
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/besto
fsoho/Movies/171/EIT171sm.mpg
16
Solar Wind
  • Blows charged particles and magnetic fields away
    from the Sun
  • Charged particles captured by Earths magnetic
    field
  • Create Auroras or Northern and Southern Lights

Image at http//solarscience.msfc.nasa.gov/the_key
.shtml
17
Auroras
  • Electrons from solar wind are captured by the
    Earths 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/a
nimation/Solarwind.mpg
18
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/C
3May97/C3May97sm.mpg
  • The eruption of a huge bubble of hot gas from the
    Sun

19
CMEs 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
20
Activities
  • Lets go observe the Sun
  • Sunspot graphing

21
Influences on Earth
  • Gravity
  • Light (Radiation)
  • Solar Wind (already discussed)

22
Gravity
  • Orbits
  • The Suns powerful gravity keeps the planets in
    orbit

23
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

The Sun at X-ray wavelengths
Image and info at http//imagine.gsfc.nasa.gov/doc
s/teachers/gammaraybursts/imagine/page18.html
and http//starchild.gsfc.nasa.gov/docs/StarChild/
solar_system_level2/sun.html .
24
Activities on Sunlight
  • UV Man (or woman, or dog, bug, etc.)
  • Observations of infrared light using filters and
    cell phones

25
Suns Radiation at Earth
  • The Earths 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

Electromagnetic spectrum http//coolcosmos.ipac.c
altech.edu/cosmic_classroom/ir_tutorial/what_is_ir
.html .
26
Sunlight is absorbed by Earth
  • Lets test what happens to the light.
  • Activity Time!!

27
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 Suns light is absorbed by Earth (clouds,
    plants, oceans, rock)
  • By absorbing the light, we are transforming it
    into heat energy

28
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

Credit NASA GSFC Water and Energy Cycle
http//www.nasa.gov/centers/jpl/news/grace-200612
12.html
NASA image at http//visibleearth.nasa.gov/view_re
c.php?id107
29
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
30
Young stars form in nebulaefrom Small
Magellanic Cloud
Image at http//hubblesite.org/newscenter/archive/
releases/2007/04/image/a/results/50/
31
Star-forming region in the Large Magellanic
Cloud http//hubblesite.org/newscenter/archive/re
leases/2008/31/image/a/results/50/
32
Orion image at http//hubblesite.org/newscenter/ar
chive/releases/2006/01/image/a/results/50/
33
Our Sun is a Regular/ Small Star
Image at http//www.gsfc.nasa.gov/topstory/2001121
0insidesun.html
34
In a few Billion years Red Giant
Image at http//hubblesite.org/newscenter/archive/
releases/1997/26/image/a/
35
Our Suns Habitable Zone
  • Billions of years ago, things may have been
    different
  • The Sun was cooler (by up to 30!)
  • Earths atmosphere was different (thicker, carbon
    dioxide)
  • Conditions will be different in the future
  • By many accounts, increases in the Suns
    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_BHabita
bleZone.MPG
36
By 5 billion years White Dwarf
Image at http//hubblesite.org/newscenter/archive/
releases/nebula/planetary/1998/39/results/50/
37
Image at http//hubblesite.org/newscenter/archive/
releases/nebula/planetary/2000/28/image/a/format/w
eb_print/results/50/
38
Image at http//hubblesite.org/newscenter/archive/
releases/nebula/planetary/2004/27/image/a/format/l
arge_web/results/50/
39
Massive Stars are different
Image from http//hubblesite.org/newscenter/archiv
e/releases/nebula/emission/1997/33/results/50/
40
Betelgeuse
Image from http//hubblesite.org/newscenter/archiv
e/releases/star/massive20star/1996/04/image/a/res
ults/50/
41
SupernovaMassive 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/
42
Done with the Sun
  • Time for Seasons!
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