Ch 22 The Sun & It’s Solar System

http://www.brainpop.com/science/space/sun/index.weml

I. Safe Methods for Studying the Sun

1. Spectroscope2. Solar Telescope3. Satellites

1. Spectroscope

a. Chemical compositionb. Temperaturec. Internal Pressure

2. Solar Telescopes Projects a large image of the

sun into a dark underground room

Uses special glasses for viewing

Ex. Kitt Peak National Observatory in AZ

3. Satellites

1. SOHO (Solar and Heliospheric Observatory): Study Sun-Earth Connection, launched in 1996

2. YOHKOH Spacecraft (designed to study the Sun’s Corona, launched in 1991):

3. ULYSSES in a polar orbit over the sun

Solar Max to Solar Minimum

B. Properties of the Sun

1. Average size star2. Diameter = 1,380,000 Km3. Surface Temp = 55000C4. Interior Temp = 15,000,0000C

C. The Sun’s Atmosphere

3 Regions Photosphere Chromosphere Corona

1. Photosphere

Apparent bright yellow surface of the sun

Area of Sunspots Made of Granules

Granules- the tops of individual columns of gases

Gases rise from region below the photosphere

2. Chromosphere Above Photosphere Lower part of the outer

atmosphere Seen only during a solar eclipse Colored Red by glowing Hydrogen Radiates mostly X-rays & UV Area of prominences

3. Corona

Above Chromosphere

So sparse in gas it would be considered a vacuum on Earth

Seen during a total solar eclipse as a faint, pearly light

D. Solar Features1. Sunspots- Dark, cooler areas on

the photosphere that occur in cycles Dark center called an umbra Lighter rim called penumbra

Occur in pairs of opposite magnetic charge, like a bar magnet

Appear to move from left to right across the photosphere

2. Solar Prominences Huge loops of gas

that connect different parts of sunspot regions

3. Solar Flares Sudden eruption of heated

hydrogen & energy around the area of a sunspot (a prominence that has exploded)

Directly correlated to sunspot # (#of sunspots ,# of solar flares)

Source of Solar wind bursts http://www.trschools.com/staff/g/cgir

tain/flare1.mpg

4. Solar Wind Constant stream

of electrically charged particles coming from the corona

Given off in all directions

5. Coronal Holes

Great tears in the Corona

May extend halfway around the sun

Do not close for several months

Source of solar winds

6. Auroras Northern Lights = Aurora Borealis Particles of solar winds interacting

with Earth's Magnetic Field & upper atmosphere

Mostly occur in Earth's polar regions

7. Magnetic Storms When particles thrown out by coronal

holes & solar flares are added to the constant solar winds

Auroras may be seen at middle latitudes

Compasses may read incorrectly Cellular & cordless telephone

reception may be interrupted May interfere with radio frequencies

Sun Spots to Auroras

Aurorasv is ib le a t p o les

Aurorasv is ib le a t lo we r la t itu d es

M agnetic Stormso ccur

Solar W indb u rsts p ro du ced

Solar Flaresin c re a se

Sunspot# in c re a ses

E. Source of the Sun’s Energy

E=mc2 Matter can be converted to energy &

vice versa Fusion Reactions: Hydrogen that

doesn’t become Helium becomes Energy

5 Billion years of fuel left in the sun Core is only place on sun where

temp, density & pressure are all great enough to sustain nuclear fusion.

II. Observing the Solar System Solar System includes:

    1. 8 Planets    2. Many Natural Satellites (moons)    3. Asteroids, Meteoroids, Comets

Solar System Cont’4. All of the planets travel in elliptical

orbits (paths around the sun) 5. 5 planets can be seen without a

telescope Mercury Venus Mars Jupiter Saturn

6. Meteors can also be seen

B. Planets & Stars

1. Position of planets related to constellations changes constantly

2. Planets move through the Ecliptic (path through the Zodiac Constellations)

3. Most planets move eastward, night after night through the sky

Retrograde Motion

C. Retrograde motion Apparent westward loop of a planet

in its path across the sky Occurs because each planet travels

around the sun at different speeds Planet appears to move backward

when the Earth overtakes it. The more distant the planet is the

slower it changes

D. Solar System Models

1. Heliocentric Sun centered model of solar system

Present day model Developed by

Copernicus (1473-1543)

2. Geocentric

Earth centered system Developed by Ptolemy 140 AD

 a. epicycles- small orbit of a planet b. deferent- large orbit of planets around the Earth

III. Motions in the Solar SystemA. Tycho Brahe (1546-1601) 1st Long Term Sky Observations (20 years

worth) Supported geocentric model Believed Sun & Moon revolved around Earth Thought other planets revolve around sun Several versions, some have Earth rotating Recognition of failure of Ptolemy's model

B. Johannes Kepler Inherited Tycho's

work

Supported Heliocentric Model 

Designed 3 Laws of Planetary Motion

3 Laws of Planetary Motion 1st Law - Planets travel in elliptical

orbits with the sun as the focus      a. Aphelion - pt. in planet's orbit where it is furthest from the sun      b. Perihelion - pt. in planet's orbit nearest the sun   

2nd Law Equal Area Law

a. Speed of a planet around the sun is not constant

b. Planets travel more rapidly when closer to the sun

http://home.cvc.org/science/kepler.htm

http://www.sciencejoywagon.com/physicszone/lesson/03circ/keplers.htm

3rd Law is the Harmonic Law The time it takes a planet to travel

one orbit around the sun = its period P2=D3    P is the period measured in years & D

is distance in AU (astronomical units) The further a planet is from the sun,

the longer its revolution

C. Galileo

1. 1st Astronomer with a telescope2. Drew craters he observed on the 

surface of the moon3. Discovered 4 largest moons of

Jupiter4. His findings supported the

heliocentric model of the solar system   

D. Sir Isaac Newton Universal Law of Gravitation:    

Change in Force =  1                             d2

Gravity & Distance are inversely correlated

Gravity & Mass are directly correlated

                

Newton’s Worka. Force of gravity between any 2 objects

is related to the distance between the objects & the masses of the two objects

b. Calculated the mass of planets from dimensions of orbit

c. Thought tides were caused by force of moon as it revolves around Earth

d. Used gravity to explain the long orbit of comets & proved they are a part of the solar system

VI. Other Objects in the Solar System

A. Asteroids - large piece of rock in space; largest is Ceres, then Pallas

B. Escape Velocity- minimum velocity needed to escape the gravitational pull of a planet, moon, or asteroid

http://www.spaceweather.com/Scroll down for near Earth misses

ASTEROID FLYBY On March 3rd,2003 a 25-meter wide asteroid,

2003 DW10, flew past Earth only 1.4 times farther from our planet than the Moon. John Rogers of the Camarillo Observatory captured this image of the 17th magnitude space rock on March 2nd. Rogers tracked the asteroid, not the stars, so 2003 DW10 appears as a point-like speck in the middle of the image. The surrounding stars are streaked. [3D orbit] [ephemeris]

C. Kuiper Belt

Vast disk of icy comets starting near Neptune’s orbit

D. Comets- Composed of dust & rock particles

mixed in with frozen water, methane & ammonia; most have very eccentric orbits

Comet Hyakutake:

Photograph by M.Geyser.

Parts of a comet:

1. Coma - hazy, melting ice cloud around the solid part of the comet

2. Nucleus - solid ball of the comet3. Tail - formed by the solar winds

pushing away small melting particles; always faces away from the sun

4. Ex. Halley’s, Encke’s, & Hale-Bopp 

Comets

E. Meteoroids - The small pieces of rock moving

from space; possibly left over from a fully melted comet

F. Meteor - a meteoroid that burns up in Earth’s atmosphere; glows as it is falling

G. Meteorite - The part of a meteoroid that did not

totally burn up & strikes the Earth, sometimes making a crater (Barringer Crater Az 25,000 yrs ago)

Antarctic ice caps have the most meteorites

Meteor craters are common on moons & some planets, but not on Earth because:1. atmosphere burns Meteors up2. Earth is geologically active & weathering occurs; erases some of the marks