Download 24.1 The Study of Light - Buncombe County Schools System

24.1 The Study of Light
Visible light from sun is only a small
part of what’s emitted
Electromagnetic waves
– Radio waves, IR, light, UV, X-rays
– Wavelength is the difference
– ROYGBIV
186,000 miles/hr…all waves
Light
Comes in “packets” called photons
Is both a waves and a particle
Radiation pressure is the “push” of
the particle of light
Spectroscopy = the study of light’s
properties
Spectra
1. Continuous spectrum
-
A continuous band of color
Spectra
2. Absorption spectrum
-
Dark lines running through it
Spectra
3. Emission spectrum
-
Bright lines emitted
A star’s spectra = its fingerprint…tells
what elements are in the star.
Doppler Effect
The change in frequency, either higher
or lower, when wave source is moving.
The pith gets higher or lower for sound.
Applies to any wave
Higher (blue shift) – moving to us
Lower (red shift) – moving away
A red shift
A blue shift
24.2 Tools to Study Space
Refracting Telescope
Reflecting Telescope
Radio Telescopes
Hubble Space Telescope
Others
Refracting Telescope
Uses a big lens to focus light
– Upside down image
– Blue and red light don’t focus at the
same place!
– Lens is heavy and can distort images
– Not the “big” telescopes of today
Reflecting Telescope
Uses a big mirror to collect light
+ doesn’t sag (weighs less)
+ cheaper glass
+ can be bigger/stronger
– the second mirror is in the way of the
light
Optical Telescope Properties
Light gathering power
– Amount of light it can get
Resolving power
– Finer detail ability
Magnification power
– Magnifies it
Radio Telescopes
“Sees” radio waves
Satellite dishes are good enough
Weak signals so the telescopes are
huge!
Poor resolution so they “hook up”
with other radio telescopes
VLA = very large array
Radio Telescopes
Less affected by weather
24/7 viewing
See through interstellar dust
No observatory = cheaper
Detect cool objects (no light seen)
Detect human radio signals
HST
In orbit above earth
NO air interference
Launched 1990
8 foot mirror
10 billion times stronger than the
human eye!!!
24.3 The Sun
Just 1 of 10,000,000,000 stars in
Milky Way
Joe average star
Only close star for study
109 earths wide
1.25 million earth’s volume
Sun Facts
IT’S A GAS…it doesn’t have a solid
surface!
4 parts
– Interior
– Photosphere
– Chromosphere
– Corona
Interior
Nuclear fusion provides energy
4 hydrogen make 1 helium & energy
Mass is lost in reaction… E = mc2!
4 million tons of hydrogen are lost
each second …
Can still last for 10 billion yrs!
Internal temp = 15 million degrees!
Photosphere
A 300 mile thick surface covering
Looks grainy on surface
– From rising/sinking hot gas
– Convection currents
90% hydrogen, 10% Helium (sun)
6000 degrees
Chromosphere
Thin atmosphere layer
Oh boy
Corona
Another thin layer of hot gases
Extends 600,000 miles out
Hot gas “blows” out from sun = solar
winds, at 500 miles/sec
Causes the Northern Lights
1,000,000 degrees
The Active Sun
Spins on axis like planets
25 days at eq, 33 days near top/bot
Sunspots = dark regions
On an 11 year cycle
Prominences – ejected material
Solar flares – bright sunspots that
eject material and high energy
Aurora Borealis – form solar flares
A radio image of the sun