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Light and Telescopes. A Telescope is a tool used to gather light from objects in the universe. There are two different types of telescopes. A refracting telescope uses a glass lens to concentrate incoming light A reflecting telescope uses mirrors to concentrate incoming starlight.

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There are two different types of telescopes
There are two different types of telescopes the universe

  • A refracting telescope uses a glass lens to concentrate incoming light

  • A reflecting telescope uses mirrors to concentrate incoming starlight


Three main functions of a telescope
Three main functions of a telescope the universe

Most important!!

  • Gather More Light – (bigger = better) making objects appear brighter

    followed by

  • to see fine detail

    (called resolution)

    and least important,

  • magnify

    magnification = (objective lens focal length / eyepiece lens focal length)



If you pass white light through a prism it separates into its component colors
If you pass white light through a prism, it separates into its component colors.

long wavelengths

ROY G B I V

short wavelengths

spectrum


But visible light is only one type of electromagnetic radiation light emitted by stars
But visible light is only one type of electromagnetic radiation (light) emitted by stars

Astronomers are interested in the entire spectrum of Light!




Observations at other wavelengths are revealing previously invisible sights
Observations at other wavelengths are revealing previously invisible sights

UV

infrared

Map of Orion region

Ordinary visible


Hubble Space Telescope Views of Orion Nebula showing stars hidden in clouds

http://oposite.stsci.edu/pubinfo/pr/97/13/A.html


Sun as seen in visible light from Earth and from space in X-rays by satellites

http://solar.physics.montana.edu/tslater/real-time/


Radio telescopes
Radio telescopes X-rays by satellites




Atmospheric seeing X-rays by satellites


How can we improve the image quality? X-rays by satellites

Bigger telescope mirror

Location, location location! (mountain tops, space)

Adaptive optics



Earth s atmosphere refracts light images are blurry

Image of stars taken with a telescope on the Earth’s surface

Same picture taken with Hubble Space Telescope high above Earth’s blurring atmosphere

Earth’s atmosphere refracts light: images are blurry!



visible surface

Near infrared



Tutorial telescopes and earth s atmosphere pg 43
Tutorial: Telescopes and Earth’s Atmosphere pg. 43 surface

  • Work with a partner!

  • Read the instructions and questions carefully.

  • Discuss the concepts and your answers with one another. Take time to understand it now!!!!

  • Come to a consensus answer you both agree on.

  • If you get stuck or are not sure of your answer, ask another group.


Which is the correct reasoning for why a gamma ray telescope located in Antarctica that is to be used to look for evidence of black holes in the centers of galaxies would not get funded?

  • There is no way to detect the presence of a black hole.

  • Gamma rays are too energetic to detect with a telescope.

  • You can’t build a functioning telescope in Antarctica.

  • Gamma rays don’t penetrate Earth’s atmosphere.


Imagine you’re the head of a funding agency that can afford to build only one telescope. Which of the three proposed telescopes below would be best to support?

  • A gamma ray telescope in Antarctica

  • A radio telescope in orbit above the Earth

  • A visible telescope located high on a mountain in Peru

  • An ultraviolet telescope located in the Mojave desert


Imagine that you throw a ball directly upward. Which of the following statements best describes how Newton’s second law accounts for the motion of the ball when it reaches its maximum height?

  • The ball has a velocity that is zero and an acceleration that is zero.

  • The ball has a velocity that is upward and an acceleration that is downward.

  • The ball has a net force that is downward and a velocity that is downward.

  • The ball has a net force that is downward and an acceleration of zero.

  • The ball has a net force that is downward and an acceleration that is downward.


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