Download Chapter 20 The Universe

Chapter 29-30 The Universe
Section 1 The Sun
1.) Sun’s gravity holds planets in orbit.
2.) Planet’s orbits and make up is related to distance from sun.
3.) Sun’s energy life
Sun’s Body
-average star
-109 x larger than Earth’s diameter
-333000 x mass of Earth
- 99.85% of all mass in solar system.
1. Core
- H and He
- 15 million degrees C
-plasma
2. Radiation Layer
-heated by core through radiation
- 3 million degrees C
3. Convective Layer
-energy transformed by convection currents
- 1.1 million degrees C
4. Photosphere “sphere of light”
- visible surface (like bubbling pots surface)
5500 degrees C
-Granules =small bright area
=tops of rising columns of gas
=darks areas are sinking areas
Sun’s Atmosphere
1. Chromosphere- above photosphere
- “sphere of color” bright red
- 2500 km thick
- 100,000 degrees C (hotter!)
-only seen during solar eclipse photosphere is blocked
-Solar prominences- erupting clouds of gas that fall back to sun
Motions & Activities of Sun
-energy at Earth now was created at sun’s core about 3000 yrs ago
H+HHe+ energy (FUSION)
-moves slowly to surface and become light
-8 minutes (light earth)
-rotates on its axis (counterclockwise) but not all areas rotate at same speed
Slower at poles
At equator, 1 sun day= 25 earth days
-sunspots- dark areas of intense magnetic activity
-cooler (dark)
- 11 yr cycle (quiet now)
- t;-; ions speed up and escape surface
-causes increased solar wind
-solar flares-eruptions near sun spots. Solar wind reaching earth disturbs
magnetic field and communications causes Auroras.
Section 2 Other Stars
Star= mass of H & He
Universe= all the matter and energy that exists
Clump of dust bigger hotter 1 million degrees C
STAR
(fusion)
New stars are still forming!
(orion)
H & H He
Glows
Group of stars= constellation
Ancient Greeks (44)
Today (88)
Star in a constellation aren’t really related.
North Star (POLARIS) doesn’t move!
TRUE NORTH
Others move around it depending on time of day and year.
Brightness
Apparent magnitude- brightness as it appears from Earth. Depends on
1. how much light is emitted.
2. Distance from Earth
Absolute magnitude= luminosity
How much light is really emitted.
Ancient Greeks- 6 magnitudes
1st magnitude- brightest
2nd
3rd
4th
5th
6th barely visible with unaided eye
-telescope- 25th magnitude is visible
- negative magnitude are very bright
Sun(-27)
Orion’s rt shoulder= Betelgeuse
Lt leg= Rigel
Sirius- follow orion’s belt to lt.
“dog star” brightest star in sky
-1.45
-Supernovas
- brightest of all stars (once thought to be a new star)
“new”
- end of life; exploded blowing matter intospace
-
brightest 100s of billions x brighter for days or years
- Star’s color and temp. are related
Blue---------- Reddish
Hottest
Color
Hertzsprung Russell Diagram p. 605
Super giants- largest brightest
Dwarfs- smallest ; densest; dimmest
Discover by Dong p 604
-sun is middle aged
-all H will be suded up in another 4.6 billion yrs
-core will contract/ temp ^/ surface expands
-will become a red giant = old star, expanded with low surface temp.
(Mercury and Venus will burn up)
-core gets hotter/ surface blows off= white dwarf
(fusion stops)
-
(small but dense!)
cools for billions of years black dwarf(cold cinder)
Neutron Stars and Black Holes
Large star development
H in core is depleted;
Core can’t support weight;
Shrinks violently and may explode= SUPERNOVA
-90% of mass is scattered and collects in a dust cloud= NEBULA
- 10% (core) falls inward NEUTRON STAR
(very small)
Very dense
-may rotate and have magnetic field
-may give off radio waves (look like blinking light)
PULSAR
-if core of supernova is 3x mass of sun collapse
Greats a black hole (gravity won’t allow energy to escape).
Section 3 Galaxies
Distance in space is measured on LIGHTYEARS-
Distance that light travels in 1 yr.
~10 billion km
Sirius (Dog star) only 9 light years away
Proxima Centauri (closest) 4.25 light yrs
Other than sun
Galaxy- large grouping of stars
-our solar system is part of Milky Way Galaxy
- what we see as the Milky Way is only the edge
(spiral galaxy)
Andromeda Galaxy 2.3 m.l.y.
Seen in Andromeda (spiral)
Large & small Magellanic Clouds- seen from s. hemisphere
27 others seen through telescopes
Billions of Galaxies
Great Wall- huge group of galaxies
-not held together by gravitation
Quasars- (quasi-stellar radio source)
-don’t show up as visible light
- small, fast-moving star-like objects
- may be oldest objects in universe
- emit lots of energy
- may be near black holes
Big Bang Theory
15 billion yrs ago – explosion
- eventually cooled and clumped together
* universe is still expanding
Light changes color as source moves toward or away form viewer
Light moving away Red
Light moving toward us Blue
* all far away galaxies are moving away ( red shift)