Transcript Chapter 26 ~ Stars and Galaxies Section 1 ~ Constellations

Chapter 26 ~
Stars and Galaxies
Section 1 ~
Constellations
Chapter 26 Section 1
Before you read - write the reading’s objectives in this space:
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What is a Constellation?
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•Constellations and the stars that
make them up are visible with the
unaided eye.
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What are telescopes used for? ____________________
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There are two basic types of optical telescopes, what are
they?
1- _________________- Uses only lenses to study light.
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Light passes through the objective lens. The eyepiece then magnifies the image.
2- A ________telescope uses a mirror as an objective to
reflect light to the focus.
Light passes through the open end of a reflecting telescope and strikes a concave
mirror at the base of the telescope.
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How can you can find the magnifying power (Mp) of a
telescope?
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Formula:
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What would the magnifying power for a telescope with a
focal length of 3,000mm and an eyepiece with a focal
length of 40mm be?
Formula:
Plug in and solve:
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If the focal length of a telescopes objective is 800mm and the
magnifying power of the telescope is 40 times, what is the
focal length of the eye piece?
Formula to use:
Plug in and solve:
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The most recent innovations in
optical telescopes involve active
and adaptive optics.
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What does adaptive optics do?
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What is a radio telescope?
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Radio waves have long wavelengths,
a radio telescope must be built with
a very large objective, usually some
form of dish antenna.
Astronomers often build several
radio telescopes close together
and connect them to form one
large telescope.
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Hubble Space Telescope
Even using active and adaptive optics, the
atmosphere limits what Earth-based telescopes
can achieve. For this reason, astronomers use
space telescopes, such as the Hubble Space
Telescope.
How Hubble Sees (2 min)
Hubble Repair (1 min)
What is a light-year?
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What is a spectroscope? ________________________
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Can you think of a time when we did something similar?
**This can tell astronomers a
great deal about a star. For
example, they can determine its
chemical composition, its surface
temperature, and whether it is
moving away from or toward
Earth.
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What does a spectroscope do?
A spectroscope helps us find out what stars are made of. It disperses, or separates,
white light from a star into a very wide spectrum of colors — much wider than a
normal prism does. When spread very wide, black lines appear in the spectrum.
The first scientists to observe these lines wondered why they were there and what
they meant. It turns out that particular elements in the star created particular
patterns of lines. Once scientists knew the element responsible for a certain pattern,
they knew which elements were present in the star. This was a revolutionary
discovery.
Section Check
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Question 1
A refracting telescope uses a _______ as
an objective.
A. mirror
B. wave
C. convex lens
D. laser
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Section Check
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Question 2
What does a spectroscope do?
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Section Check
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Question 3
What is the distance that light travels
in one year?
A. 15 million km
B. 9.5 trillion km
C. 12 billion km
D. 2 million km
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