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The sun and our solar system
Grade 9 ScienceSpace Part 2
Astronomy: The branch of science that studies objects beyond the Earth (in “outer space”)
Celestial body: Any object in space
The Universe: Everything that exists
Key Terms
Star: A massive celestial body composed of hot gases that radiates large amounts of energy
Luminous: glowing, light producing
Planet: a celestial body which orbits a star
Satellite: a celestial body which orbits another body
Orbit: the closed path an satellite takes around another body
Moon: a natural satellite of a planet
Solar system: the Sun and all of the celestial bodies that orbit it
Our Star: The Sun Core Temperature: 15,000,000 °C
http://www.universetoday.com/18847/life-of-the-sun/
• 100 billion tonnes of Dynamite would have to be detonated every second in order to match the Sun’s energy output!!
• The sun is getting hotter…becoming 10% more luminous every billion years
• If the sun where to “turn off”, within a week the temperature of the earth would be zero degrees F
DID YOU KNOW?!?
http://www.funonthenet.in/articles/scale-of-the-universe.html
Age: 5 billion years
Diameter: 1,391,000 km (109 X
the size of Earth)
Composition:
94% Hydrogen
6% Helium0.13% other
High temperature + High pressure
=
Particles moving quickly and colliding at high speeds and fusing
Releases enormous amounts of energy
What human energy source does this remind you of?
The Sun’s Energy Source: Nuclear Fusion
http://www-istp.gsfc.nasa.gov/istp/outreach/workshop/thompson/sundiag.html
Core: - 2% of Sun’s volume, 50% of Sun’s mass.
DENSE!!!- nuclear fusion happens here…600 tonnes of
H to He per second- 15000000°C
Radiative zone:- Energy moves away from the core- Photons can take up to 1 million years to
reach the next layer- 380,000 km thick- 32% of sun’s volume, 48% of sun’s mass- 5000000 °C
Layers of the Sun
Layers continued…
Convective zone: - 66% of Sun’s volume, 2% of Sun’s mass (LOW
DENSITY)
- Convective currents form “cells”- hot gas rises (away from core)- cool gas falls (toward core)- 5500°C
Photosphere: - Visible “surface” (NOT solid!) looks like boiling liquid
- Light and other radiation begins to escape
- 6000°C
- 140,000 km thick
Chromosphere: - 6000-20000°C
- Thousands of kilometers thick
- Composed of spicules
Corona:- Visible during a full solar eclipse
- 1,100,000°C
The Sun’s “Atmosphere”
http://www.nasa.gov/vision/universe/solarsystem/ring_of_fire_mm.html
http://www.enchantedlearning.com/subjects/astronomy/sun/sunstructure.shtml
http://climate.nasa.gov/interactives/sun
Video
https://www.youtube.com/watch?v=C2FETG7tCF0
Virtual Tour
Sunspots on the Photosphere
http://broadcast.homestead.com/Swedish_20sunspots1.jpg
• Cooler regions on the photosphere (1000-1200ºC cooler)
• Do not emit as much light and appear darker.
• Can last a few days to a few months.
• Largest ever: 1.8*1010 km2 (36 x Earth’s surface area!!)
http://www.crh.noaa.gov/fsd/?n=sunspots
http://oneminuteastronomer.com/wp-content/uploads/2009/09/sunspots_recent_history.jpg
Solar Storms
- Gas and charged particles emitted from the sun’s surfaceCoronal Mass
Ejections• Lower energy• Ejection of gas• last several
days to several weeks
Flare:• Higher energy • Gas and charged
particles ejected• last a few minutes
to a few hours• Occur near
sunspots
http://www.youtube.com/watch?v=HFT7ATLQQx8
http://www.spaceweather.sflorg.com/space_weather/sdo_2010/sdo_02
http://www.spaceweather.sflorg.com/space_weather/sob_multimedia/flvswm_15
http://en.wikipedia.org/wiki/Coronal_mass_ejection
Solar Activity Affects the Earth
1. Solar winds are guided by the Earth’s magnetic field (strongest near the poles)• They interact with particles in the Earth’s
atmosphere, creating the aurora borealis and aurora australis
http://en.wikipedia.org/wiki/Aurora_(astronomy)
http://en.wikipedia.org/wiki/Aurora_(astronomy)
http://en.wikipedia.org/wiki/Aurora_(astronomy)
2. Solar activity/storms can…• interfere with satellites and
cellphone/TV connections • Cause increased radiation for
astronauts
3. The sun provides all of our incoming energy!• In the form of electromagnetic
radiation
Electromagnetic (EM) radiation
http://upload.wikimedia.org/wikipedia/commons/c/cf/EM_Spectrum_Properties_edit.svg
• Blocks (reflects) bad radiation (UV)
Role of our Atmosphere
• Lets in (absorbs) good radiation (infrared and visible)
• Insulates the Earth: keeps us warm, keeps temperatures from swinging drastically in the day and the night, the summer and winter.
http://uhaweb.hartford.edu/GKAUFMAN/
EM radiation = heat
CO2 traps heat!
Reading: 320-328
Textbook questions:
#2-3 on pg. 308, #2-5, and 8-9 on pg. 312
Homework
The solar system
Sourceshttp://www.iflscience.com/space/take-virtual-tour-sun
http://www.astronomynotes.com/starsun/s2.htm#A1.3
http://sunearthday.nasa.gov/2006/educators/lp_k5.php
http://www.youtube.com/watch?v=UgpIy4tUjFI