3.0 – TELESCOPES AND INTERPRETING SPACE

3.1 Telescopes -

A. Optical Telescopes – gather and focus light of stars to create a visible image of stars

- the larger the area of the lens, the more clear the light

1. Refracting telescope- uses 2 lenses to enlarge images (images are upside down)

Eyepiece lens #2

Lens #2

3.1 . Telescopes

2 . Reflecting Telescopes – Uses a mirror to gather and focus light

-can pick up more faint light than reflecting

Video clip: Telescopes

Summary of Telescopes

Refracting Reflecting Uses two lenses to

focus and gather light Used best for looking

at objects within our galaxy

Planets, moons, etc.

Uses a lens and mirrors to gather/focus light

Best used for viewing far away objects – is better at gathering and focusing light

3.1 - TelescopesB. Interferometry – using 2 or more

telescopes in combination to improve the resolution (clarity and details) of images

Array used on the Andes Mountains in ChileVLT (Very Large Telescope) Is a collaborative effort between NA, Europe and East Asia

The Keck Interferometer links two 10-meter (33-foot) telescopes on Mauna Kea in Hawaii. The linked telescopes form the world's most powerful optical telescope system. They will be used to search for planets around nearby stars, as part of NASA's quest to find habitable, Earth-like planets

Military array of telescopes in Arizona

***Array – the arrangement of telescopes used for interferometry

3.1 Telescopes

C. Hubble Space Telescopeo A reflecting telescope 600km above

Earth’s surfaceo Allows star-gazing without

interruption of cloudso Rotates Earth every 95 mins. Which orbit would the Hubble Space

telescope be placed in?

Hubble Space Telescope

Picture from Hubble Space Telescope of nearby spiral galaxy Messier 74. [2007]

Picture from Hubble Telescope of Crab Nebulae. The Crab Nebulae is the reminants of a supernove and in the center lies a neutron star. [6500 light years from Earth]

3.2 Seeing Beyond Invisible

A. Electromagnetic Energy - a form of energy that travels in waves through space

o Includes: infared, visible light, ultraviolet light

o Wavelength – length of the waveo Frequency – the amount of waves that

pass through a point in a secondo High frequency energy has low

wavelengtho Low frequency energy has high

wavelengths

3.2 Seeing Beyond Invisible

3.2 Seeing Beyond InvisibleB. Radio Telescopeso Pick up radio waves and create maps

of the galaxyo Radio waves are emitted by planets,

the Sun, stars, etc.o Advantage over Light Waves: These

waves are unaffected by weather or the atmosphere

o Video Clip: Milky way emits radio waves

3.2 Seeing Beyond InvisibleC. Ways to Improve Radio Telescope

Maps1. Interferometry – combine two or

more radio telescopes (will be better than 1 large one)

2. Increase distance between telescopes (can better plot positions)

3. Arrange telescopes into arrays – (Y shapes)

Review Video: http://www.youtube.com/watch?v=YtXSv59AxYw

3.3 Interpreting SpaceA. Measuring Distance1. Triangulationo Using a triangle to determine the distance

to an objecto A baseline is measured and the two angles

from the baseline ends to the objecto A drawing to scale is completed and

measured.o The longer the baseline the more accurate

the measurement

3.3 Interpreting Space

1cm = 1m

3.2 – Interpreting Space2. Parallax – is the apparent shift of an

object when it is viewed from two different places-used to determine angles for triangulationTry IT: Parallax

of Your Finger! -close one eye at a time

3.2 – Interpreting SpaceB. Determining A Star’s Compositiono A spectroscope is used to determine

what elements a star is made ofo Each element makes a distinct

thickness and location in a visible light spectrum

http://www.colorado.edu/physics/2000/applets/doppler2.html -

Why does the sound change???

C. Determining A Star’s Movemento Doppler effect- when the movement

of an object makes waves compress or spread out

o Makes an object coming closer sound higher in pitch and lower moving away

o Stars moving towards Earth show a spectrum that is blue shifted

o Stars moving away from Earth show a red shift spectrum