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.mreclipse.com/SEphoto/SEgallery1/SEgallery1.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